Microtubule/Tubulin

Experiencing 1μM The microtubule disrupting agent colchicine caused rat cerebellar granule cells (CGC) to undergo apoptosis. A moderate but progressive increase in the resting intracellular Ca²⁺ concentration is also brought on by colchicine treatment[1], as well as changes in the Ca²⁺ responses to chemical depolarization. Colchicine binds to the main structural element of microtubules, the soluble tubulin heterodimer, to initiate its biological actions. The mechanism of Colchicine binding to brain tubulin is thoroughly examined, and the capacities of tubulins to bind Colchicine from diverse sources are enumerated. Colchicine's high affinity binding to tubulin is attributed to its colchicinoid structure, which is reviewed in relation to its analogues in the Colchicine series. This relationship also sheds light on the structural characteristics of Colchicine. The association's kinetic and thermodynamic features are discussed and assessed in relation to the binding mechanism. Colchicine's low energy electronic spectra exhibit peculiar changes upon binding to tubulin. The nature of the Colchicine-tubulin complex is discussed in relation to the spectroscopic characteristics of Colchicine bound to tubulin. There are attempts to identify the high affinity Colchicine binding site on tubulin[2]. The lesion index measured 24 hours after indomethacin administration shows that colchicine treatment inhibits small intestinal injury caused by indomethacin by 86% (1 mg/kg) and 94% (3 mg/kg). Colchicine suppresses the expression of mature IL-1β and cleaved caspase-1 proteins, but has no effect on NLRP3 or IL-1β mRNA expression[3].

Vehicle or Colchicine (1 mg/kg) is put on the tongue half an hour before indomethacin. Within 24 hours of indomethacin administration, mice treated with Colchicine had smaller lesions in their small intestine when stained with Evans blue as compared to mice treated with vehicle. Furthermore, compared to mice treated with a vehicle, Colchicine-treated mice exhibit decreased mucosal inflammation and ulceration as well as a reduction in the size and quantity of lesions. This was revealed by histological examination. When administered at doses of 1 mg/kg and 3 mg/kg (by 86% and 94%, respectively), colchicine treatment dramatically lowers the lesion index in comparison to vehicle treatment. Treatment with colchicine markedly reduces the protein levels of mature IL-1β by 56% and 69%, respectively, at doses of 1 mg/kg and 3 mg/kg, without changing pro-IL-1β levels.

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Preventive effects of Colchicine treatment on indomethacin-induced small intestinal injury [3]
We confirmed that vehicle treatment without indomethacin did not cause any damaged lesions in the small intestine in advance. Vehicle or Colchicine (1 mg/kg) was administered orally 30 min prior to indomethacin administration. The lesions stained with Evans blue in the small intestine were smaller in colchicine-treated mice than those in vehicle-treated mice 24 h after indomethacin administration. In addition, histological examination showed that colchicine-treated mice had less mucosal inflammation and ulceration and a decrease in the size and numbers of lesions compared with vehicle-treated mice (Fig. 2a). Colchicine treatment significantly reduced the lesion index at doses of 1 mg/kg and 3 mg/kg (by 86% and 94%, respectively) compared with vehicle treatment (Fig. 2b).
We next investigated the effect of colchicine on the mRNA levels of inflammasome components 6 h after indomethacin administration. In comparison with vehicle treatment, colchicine treatment did not significantly change the mRNA levels of NLRP3 (Fig. 2c), IL-1β (Fig. 2d), or caspase-1 (Fig. 2e) at doses of 1 mg/kg and 3 mg/kg.

Furthermore, we examined the effect of Colchicine treatment on the protein expression of mature IL-1β (p17) and cleaved caspase-1 (p10) 6 h after indomethacin administration. Colchicine treatment significantly inhibited the protein levels of mature IL-1β at doses of 1 mg/kg and 3 mg/kg (by 56% and 69%, respectively) without affecting those of pro-IL-1β. Colchicine treatment also significantly inhibited the protein levels of cleaved caspase-1 at doses of 1 mg/kg and 3 mg/kg (by 26% and 39%, respectively) without affecting those of pro-caspase-1 (Fig. 2f–j).

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Preventive effect of Colchicine treatment on the expression and localization of cleaved caspase-1 in the damaged small intestine [3]
The localization and expression levels of cleaved caspase-1 protein were determined using immunofluorescence, which showed that cleaved caspase-1 was diffusely expressed in the lamina propria of the small intestinal mucosa 6 h after indomethacin administration, while mice treated with Colchicine exhibited a marked decrease in cleaved caspase-1 expression (Fig. 3a). Double staining of cleaved caspase-1 with CD68 demonstrated that the majority of cells expressing cleaved caspase-1 were macrophages and monocytes (Fig. 3b).

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Effect of exogenous IL-1β and Colchicine treatment on indomethacin-induced small intestinal injury [3]
To investigate the role of IL-1β in the development of NSAID-induced small intestinal damage, mice received vehicle or intraperitoneal injections of murine recombinant IL-1β (0.1 μg/kg) 3 h after indomethacin treatment. The administration of recombinant IL-1β prior to the indomethacin challenge abolished the preventive effects of Colchicine against indomethacin-induced damage in both macroscopic (i.e., lesion index) and microscopic evaluations, but IL-1β supplementation did not affect the severity of damage in vehicle-treated mice (Fig. 4a,b).

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Preventive effects of Colchicine treatment are mediated by suppression of the NLRP3 inflammasome [3]
To confirm the involvement of the NLRP3 inflammasome/caspase-1/IL-1β axis in the suppressive effects of Colchicine, vehicle or colchicine (1 or 3 mg/kg) was administered to mice with a genetic disruption of NLRP3 (NLRP3−/− mice) before the administration of indomethacin. Consistent with a previous study23, indomethacin-induced small intestinal damage was macroscopically slight in NLRP3−/− mice. Colchicine treatment did not further inhibit small intestinal damage in NLRP3−/− mice (Fig. 5a). The indomethacin-induced small intestinal damage assessed using the lesion index was significantly reduced by 77% in NLRP3−/− mice compared with that in wild-type mice, and we confirmed that colchicine treatment at doses of 1 mg/kg and 3 mg/kg failed to inhibit small intestinal damage in NLRP3−/− mice (Fig. 5b).

We investigated the effects of Colchicine treatment (1 mg/kg and 3 mg/kg) on the mRNA levels of inflammasome components in NLRP3−/− mice. The mRNA levels of IL-1β (Fig. 5c) and caspase-1 (Fig. 5d) were not significantly altered in NLRP3−/− mice compared with those in wild-type mice. In NLRP3−/− mice, and Colchicine treatment at doses of 1 mg/kg and 3 mg/kg did not significantly change the mRNA levels of IL-1β (Fig. 5c) and caspase-1 (Fig. 5d) compared with vehicle treatment.

We examined the effects of Colchicine treatment on the protein expression of mature IL-1β (p17) and cleaved caspase-1 (p10) in NLRP3−/− mice. The protein levels of mature IL-1β and cleaved caspase-1 were significantly reduced by 33% and 57%, respectively, in NLRP3−/− mice compared with wild-type mice. The protein levels of pro-IL-1β and pro-caspase-1 were not changed in NLRP3−/− mice compared with wild-type mice. The expression levels of these proteins were similar in NLRP3−/− mice with and without colchicine treatment (Fig. 5e–i).

Spending time in 1μM In rat cerebellar granule cells (CGC), the microtubule disrupting agent colchicine caused apoptosis. In addition, administering colchicine results in a gradual but moderate rise in the resting intracellular Ca2+concentration as well as changes in the Ca2+ responses to chemical depolarization [...]. By binding to the soluble tubulin heterodimer, which is the main building block of the microtubule, colchicine has its biological effects. An extensive examination of the mechanism of Colchicine binding to brain tubulin is conducted, along with a summary of the tubulins' capacity to bind Colchicine from all sources. Insight into the structural characteristics of Colchicine that enable its high affinity binding to tubulin is gained from the correlation between the structure of the colchicinoid and tubulin binding activity. This relationship is also examined for Colchicine series analogs. The association's kinetic and thermodynamic features are discussed and assessed in relation to the binding mechanism. Colchicine's low energy electronic spectra exhibit peculiar changes upon binding to tubulin. The nature of the Colchicine-tubulin complex is discussed in relation to the spectroscopic characteristics of Colchicine bound to tubulin. There are attempts to identify the tubulin's high affinity Colchicine binding site[2]. The lesion index 24 hours after indomethacin administration shows that colchicine treatment inhibits 86% (1 mg/kg) and 94% (3 mg/kg) of indomethacin-induced small intestinal injury. Without influencing the mRNA expression of NLRP3 and IL-1β, colchicine suppresses the protein expression of mature IL-1β and cleaved caspase-1.

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Colchicine exerts its biological effects through binding to the soluble tubulin heterodimer, the major component of the microtubule. The colchicine-binding abilities of tubulins from a variety of sources are summarized, and the mechanism of colchicine binding to brain tubulin is explored in depth. The relationship between colchicinoid structure and tubulin binding activity provides insight into the structural features of colchicine responsible for high affinity binding to tubulin and is reviewed for analogs in the colchicine series. The thermodynamic and kinetic aspects of the association are described and evaluated in terms of the binding mechanism. Colchicine binding to tubulin results in unusual alterations in the low energy electronic spectra of colchicine. The spectroscopic features of colchicine bound to tubulin are discussed in terms of the nature of the colchicine-tubulin complex. Attempts to locate the high affinity colchicine binding site on tubulin are presented [2].

HeLa cells are grown in 6-well plates, and after two hours, they are treated with 100 μM EBI. After that, they are treated with KXO1, vinblastine, or Colchicine at varying concentrations. After using radioimmuno_x005fprecipitation assay buffer to extract the total protein, β~-tubulin is analyzed using Western blot analysis. The loading control is GAPDH. The process of Western blotting is carried out.

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Electrophysiology [4]
Glycine-evoked currents were recorded from EGFP-positive transfected HEK 293 cells in the whole-cell voltage-clamp configuration at room temperature (20–24°C) at a holding potential of −60 mV (Lara et al., 2019). Patch electrodes (3–4 mΩ) were pulled from borosilicate glass and were filled with (in mM): 120 CsCl, 8 EGTA, 10 HEPES (pH 7.4), 4 MgCl2, 0.5 GTP, and 2 ATP. The external solution contained (in mM) 140 NaCl, 5.4 KCl, 2.0 CaCl2, 1.0 MgCl2, 10 HEPES (pH 7.4), and 10 glucose. Whole-cell recordings were performed with an Axoclamp 200B amplifier and acquired using Clampex 10.1 or Axopatch 10.0 software. Data analysis was performed off-line using Clampfit 10.1. Exogenous glycine-evoked currents were obtained using a manually applied pulse (3–4 s) of the agonist and an outlet tube (200 μm ID) of a custom-designed gravity-fed microperfusion system positioned 50–100 μm from the recorded cell. The methodologies employed for the single channel recordings of α 3GlyRs in the cell-attached configuration have been previously published (Marabelli et al., 2013; Lara et al., 2019). The patch pipettes had tip resistances of 10–20 mΩ and were manually fire polished in a microforge. The data were filtered (1-kHz low-pass 8-pole Butterworth) and acquired at 5–20 kHz using an Axopatch 200B amplifier and a 1322A Digidata. Data was acquired using pClamp software and analyzed off-line with Clampfit 10.1. Colchicine stock was prepared in high purity distilled water and subsequently diluted into the recording solution on the day of the experiment. In whole-cell experiments Colchicine was co-applied with glycine using a manually applied pulse (1–2 s). In cell-attached recordings, Colchicine was applied to the intra-pipette solution together with glycine.

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Exposure to 1 microM Colchicine, a microtubule disrupting agent, triggered apoptosis in rat cerebellar granule cells (CGC). Apoptotic nuclei began to appear after 12 h followed by oligonucleosomal DNA laddering, whereas inhibition of the mitochondrial 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide metabolism became significant between 18 and 24 h, when most cells already had apoptotic nuclei. These events were preceded by loss of tau protein and fragmentation of alpha and beta tubulins. Colchicine treatment also caused alterations in Ca2+ responses to chemical depolarization and a moderate, but progressive, increase in the resting intracellular Ca2+ concentration. Nearly all neurons expressed c-Fos after the treatment with colchicine. However, while in part of the cell population c-Fos levels subsequently declined, in the neurons undergoing apoptosis the protein was still expressed, but had an abnormal intracellular localization. An increased expression of the constitutive nitric oxide synthase (NOS-I) was also detected at 12 h and was followed by increased nitrite production. Treatment with 100 nM taxol to stabilize the microtubuli prevented DNA laddering and apoptotic body formation induced by colchicine. In contrast, pretreatment with the N-methyl-D-aspartate receptor-antagonist, MK-801, or L-type Ca2+ channel blockers did not prevent colchicine-induced CGC apoptosis. Inhibitors of NOS were also ineffective in preventing apoptotic body formation and DNA laddering, whereas they delayed the secondary cell lysis. These results support the idea that colchicine-induced cytoskeletal alterations directly initiate the genetic and structural modifications that result in CGC apoptosis[1] .

Mice: Male 8-week-old mice that are free of specific pathogens are used. Both NLRP3^?/? mice and wild-type C57BL/6 mice on a C57BL/6 background are employed. 30 minutes before indomethacin is given, either a vehicle or 1 or 3 mg/kg of Colchicine is given orally to investigate the impact of Colchicine on NSAID-induced small intestinal damage. Three hours after being treated with indomethacin, mice were given intraperitoneal injections of either mouse recombinant IL-1β (0.1 μg/kg) or sterilized phosphate buffered saline. Before indomethacin is given to NLRP3^?/? mice, vehicle or colchicine (1 or 3 mg/kg) is also given. 24 hours after indomethacin is administered, the lesion index is assessed, and 6 hours later, the mRNA and protein expression of inflammasome components is investigated.

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To examine the effects of colchicine on NSAID-induced small intestinal injury, vehicle or colchicine (1 or 3 mg/kg; Wako Pure Chemical Industries, Ltd., Kyoto, Japan) was administered orally 30 min prior to indomethacin administration. Mice received intraperitoneal injections of sterilized phosphate buffered saline or mouse recombinant IL-1β (0.1 μg/kg; R&D Systems, Inc., Minneapolis, MN) 3 h after indomethacin treatment. Vehicle or colchicine (1 or 3 mg/kg) was also administered to NLRP3−/− mice before indomethacin administration. We evaluated the lesion index 24 h after indomethacin administration, and examined mRNA and protein expression of inflammasome components 6 h after indomethacin administration.[3]

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The inflammasome is a large, multiprotein complex that consists of a nucleotide-binding oligomerization domain-like receptor (NLR), an apoptosis-associated speck-like protein containing a caspase recruitment domain, and pro-caspase-1. Activation of the inflammasome results in cleavage of pro-caspase-1 into cleaved caspase-1, which promotes the processing of pro-interleukin (IL)-1β into mature IL-1β. We investigated the effects of colchicine on non-steroidal anti-inflammatory drug (NSAID)-induced small intestinal injury and activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome. Colchicine treatment inhibited indomethacin-induced small intestinal injury by 86% (1 mg/kg) and 94% (3 mg/kg) as indicated by the lesion index 24 h after indomethacin administration. Colchicine inhibited the protein expression of cleaved caspase-1 and mature IL-1β, without affecting the mRNA expression of NLRP3 and IL-1β. Although treatment with recombinant IL-1β (0.1 μg/kg) did not change the severity of small intestinal damage, the preventive effects of colchicine were abolished by supplementation with the same dose of recombinant IL-1β. Indomethacin-induced small intestinal damage was reduced by 77%, as determined by the lesion index in NLRP3(-/-) mice, and colchicine treatment failed to inhibit small intestinal damage in NLRP3(-/-) mice. These results demonstrate that colchicine prevents NSAID-induced small intestinal injury by inhibiting activation of the NLRP3 inflammasome. [3]

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Colchicine is a plant alkaloid that is widely used as a therapeutic agent. It is widely accepted that colchicine reduces the production of inflammatory mediators mainly by altering cytoskeleton dynamics due to its microtubule polymerization inhibitory activity. However, other lines of evidence have shown that colchicine exerts direct actions on the function of ion channels, which are independent of cytoskeleton alterations. Colchicine is able to modify the function of several pentameric ligand-gated ion channels, including glycine receptors (GlyRs). Previous electrophysiological studies have shown that colchicine act as an antagonist of GlyRs composed by the α 1 subunit. In addition, it was recently demonstrated that colchicine directly bind to the α 3 subunit of GlyRs. Interestingly, other studies have shown a main role of α 3GlyRs on chronic inflammatory pain. Nevertheless, the functional effects of colchicine on the α 3GlyR function are still unknown. Here, by using electrophysiological techniques and bioinformatics, we show that colchicine inhibited the function of the α 3GlyRs. Colchicine elicited concentration-dependent inhibitory effects on α 3GlyRs at micromolar range and decreased the apparent affinity for glycine. Single-channel recordings show that the colchicine inhibition is associated with a decrease in the open probability of the ion channel. Molecular docking assays suggest that colchicine preferentially bind to the orthosteric site in the closed state of the ion channel. Altogether, our results suggest that colchicine is a competitive antagonist of the α 3GlyRs. [4]

Absorption, Distribution and Excretion
Colchicine is rapidly absorbed from the gastrointestinal tract after oral administration. The bioavailability of colchicine is approximately 45%: one study showed that bioavailability varies considerably, ranging from 24% to 88%. In healthy adults, peak plasma concentration (Cmax) of 2.5 ng/mL (range 1.1 to 4.4 ng/mL) is reached 1 to 2 hours (range 0.5 to 3 hours) after a single fasting dose. In a multiple-dose study of 1 mg colchicine daily, steady-state plasma concentrations were reached on day 8. Co-administration with food does not affect the absorption rate of colchicine, but reduces the amount absorbed by approximately 15%. In a pharmacokinetic study of 1 mg colchicine orally in healthy subjects, approximately 40% to 65% of the dose was excreted unchanged in the urine. Colchicine is excreted via enterohepatic circulation and bile. The average apparent volume of distribution in young, healthy patients is approximately 5-8 L/kg. Colchicine is known to cross the placental barrier and distribute into breast milk. Studies have shown that colchicine can be distributed in various tissues, primarily in bile, liver, and kidney tissues. Small amounts of colchicine have also been detected in the heart, lungs, intestines, and stomach. In a pharmacokinetic study, a single oral dose of 0.6 mg of colchicine resulted in a clearance rate of 0.0321 ± 0.0091 mL/min in young, healthy adults and 0.0292 ± 0.0071 mL/min in adults aged 60-70 years. Colchicine clearance was reduced by 75% in patients with end-stage renal insufficiency. In a pharmacokinetic study of patients with familial Mediterranean fever (FMF), the calculated apparent mean clearance was 0.726 ± 0.110 L/h/kg. Colchicine is rapidly absorbed, but there is significant individual variability. Peak plasma concentrations are reached 0.5 to 2 hours after administration. 50% of colchicine in plasma is bound to proteins. Significant enterohepatic circulation is present. The exact metabolic pathway of colchicine is unclear, but hepatic deacetylation appears to be involved. Only 10% to 20% of colchicine is excreted in the urine, but urinary excretion is increased in patients with liver disease. High concentrations of colchicine are also found in the kidneys, liver, and spleen, but the heart, skeletal muscle, and brain appear to absorb very little. The plasma half-life of colchicine is approximately 9 hours, but it remains detectable in leukocytes and urine for at least 9 days after a single intravenous injection. … Two cases of suicide by overdose of a French commercially available drug have been reported. In Case 1, cardiac blood was collected after only an external examination of the body. In Case 2, an autopsy was performed, and cardiac blood, urine, gastric contents, and bile were collected for toxicological analysis. Colchicine in biological samples was determined using high-performance liquid chromatography-diode array detector (HPLC-DAD). Dichloromethane at pH 8 was used prior to extraction, with plarazepam as an internal standard (IS). Analysis was performed on a Symetry C-8 column. The mobile phase was a gradient elution of acetonitrile/pH 3.8 phosphate buffer. The retention time of colchicine was 13.1 min, and the linear range of this method in blood, urine, and bile was 4–1000 ng/mL. The limit of quantitation (LOQ) was 4 ng/mL. Detected colchicine concentrations were: Case 1: cardiac blood 13 ng/mL; Case 2: cardiac blood 66 ng/mL, urine 500 ng/mL, gastric contents 12 ng/mL, bile 5632 ng/mL. Our results are consistent with previously reported lethal concentration ranges, but are independent of the amount of drug ingested. Even with a large overdose, colchicine may not be detectable in blood. Because colchicine undergoes extensive enterohepatic circulation before being excreted in bile and feces, bile is the target sample for analysis. We conclude that the cause of death in both cases was suicide by colchicine ingestion. Autopsy to obtain bile, urine, cardiac blood, and femoral vein blood samples is particularly important.
After oral administration, plasma concentrations peak within 0.5 to 2 hours, then rapidly decline within 2 hours. The plasma half-life is 60 minutes. Colchicine can remain in tissues for up to 10 days.
In 5 cases, we obtained information on urinary excretion. Urinary concentrations were 10 to 80 times higher than plasma concentrations. 4% to 25% of the ingested dose were excreted in the urine within 3 to 10 days. Excretion was particularly high in the first 24 hours after ingestion. Colchicine is primarily excreted in the urine within ten days after ingestion.
For more complete data on the absorption, distribution, and excretion of colchicine (12 in total), please visit the HSDB records page.

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Metabolism/Metabolites
Colchicine is metabolized in the liver. It undergoes CYP3A4-mediated demethylation to produce the major metabolites 2-O-demethylcolchicine and 3-O-demethylcolchicine. Additionally, it produces a minor metabolite, 10-O-demethylcolchicine (colchicine). The plasma concentrations of these metabolites are less than 5% of the parent drug.
Colchicine is partially metabolized in the liver. Colchicine undergoes partial deacetylation in the liver. Large amounts of colchicine and its metabolites circulate enterohepaticly. This may explain the second peak plasma concentration observed 5 to 6 hours after ingestion.
Three novel colchicine-bound metabolites were identified in rat bile using enhanced online liquid chromatography-precise radioisotope counting. The known 2- and 3-demethylcolchicine (DMC) undergoes O-sulfate binding in addition to the previously reported O-glucuronidation. 2-DMC preferentially undergoes O-glucuronidation, while 3-DMC primarily forms O-sulfate conjugates, indicating regioselectivity in phase II binding. Furthermore, M1 was identified as a novel glutathione conjugate, and its possible biotransformation pathway was proposed. The known 2-DMC (M6), 3-DMC (M7), 2-DMC glucuronide (M4), and the novel 3-DMC sulfate (M3) were confirmed as major metabolites. ...

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Biological Half-Life
After several doses of 0.6 mg colchicine twice daily, the mean elimination half-life of colchicine is 26.6 to 31.2 hours. Another study reported elimination half-lives of 20 to 40 hours.
Following a single intravenous therapeutic dose (as of August 2008, intravenous formulations were no longer sold in the United States), colchicine is rapidly cleared from plasma; the plasma half-life is approximately 20 minutes. The drug has a half-life of approximately 60 hours in leukocytes. The elimination half-life varies considerably among individuals, ranging from 4.4 hours in normal patients to 30 hours or longer in elderly patients. The therapeutic dose half-life in patients with renal insufficiency is 18.8 hours. Following a single intravenous injection of 2 mg, the mean plasma half-life is 20 minutes. The plasma half-life is prolonged (40 minutes) in patients with severe kidney disease and shortened (9 minutes) in patients with severe liver disease.

Toxicity Summary
Identification: Colchicine is an anti-gout preparation. Colchicine is available in tablet form, and in some countries, it is also available in injectable form. Colchicine is an alkaloid of the autumn crocus (Colchicum autumnale, also known as autumn saffron or meadow saffron). Autumn crocus is also found in Gloriosa superba. Colchicine is a pale yellow, odorless powder or scaly substance that turns black upon exposure to light. Colchicine is used to treat acute gout attacks to relieve pain and inflammation. It can also be taken long-term to prevent or reduce the frequency of gout attacks. Long-term use of colchicine can prevent fever and recurrent polyserositis. Colchicine is effective in preventing amyloidosis in this disease. Colchicine has been shown to be effective in treating joint, skin, and mucous membrane symptoms. Colchicine has been used to treat scleroderma and sarcoidosis. Human Exposure: Major Risks and Target Organs: Colchicine has multi-organ toxicity. The primary toxic effects are related to its influence on cell division, leading to diarrhea, bone marrow suppression, and hair loss. Other acute effects include hypovolemia, shock, and coagulation disorders, all of which can be fatal. Clinical Effects Overview: Symptoms of poisoning typically appear 2 to 12 hours after ingestion or parenteral administration. Symptom development occurs in three phases: Phase 1 (Days 1-3): Gastrointestinal and circulatory phase: Severe gastrointestinal irritation: nausea, vomiting, abdominal cramps, severe diarrhea. Dehydration, hypovolemia, shock. Cardiogenic shock may occur and can lead to death within the first 72 hours. Hypoventilation, acute respiratory distress syndrome. Phase 2 (Days 3-10): Bone marrow aplasia phase: Bone marrow aplasia with agranulocytosis. Coagulation disorders with diffuse hemorrhage. Rhabdomyolysis, polyneuritis, myopathy, acute renal failure, and infection. Phase 3 (After 10 days): Recovery phase: Hair loss. Route of Administration: Oral: Oral absorption is the most common cause of poisoning. Parenteral administration: Poisoning after parenteral administration is rare, but the toxic dose appears to be lower than the oral toxic dose. A 70-year-old man developed fatal myeloablative dysplasia after intravenous administration of 10 mg colchicine over 5 days. Multisystemic toxicity occurred after colchicine instillation into the penile urethra for the treatment of condyloma acuminata. Absorption routes: Oral: Rapidly absorbed via the gastrointestinal tract. Peak plasma concentrations are reached 0.5 to 2 hours after oral administration. The absorption half-life is 15 minutes. Absorption may be affected by pH, gastric contents, and intestinal motility. Colchicine is not completely absorbed. A significant first-pass effect exists in the liver. The volume of distribution of colchicine is greater than its volume of distribution in the body. In severe kidney or liver disease, its volume of distribution may be reduced. Colchicine accumulates in the kidneys, liver, spleen, gastrointestinal wall, and leukocytes, but does not appear to enter the heart, brain, or skeletal muscle. Colchicine crosses the placenta and has been found in breast milk. Biological half-life of different routes of administration: Parenteral administration: After a single intravenous injection of 2 mg, the mean plasma half-life is 20 minutes. Severe renal disease prolongs the plasma half-life (40 minutes), while severe hepatic disease shortens it (9 minutes). Oral administration: After oral administration, plasma concentrations peak within 0.5 to 2 hours, then rapidly decline within 2 hours. The plasma half-life is 60 minutes. Colchicine can remain in tissues for up to 10 days. Metabolism: Colchicine is metabolized in the liver. Colchicine is partially deacetylated in the liver. Large amounts of colchicine and its metabolites circulate enterohepaticly. This explains the second peak plasma concentration observed 5 to 6 hours after ingestion. Elimination via exposure: Colchicine is excreted unchanged (10% to 20%) or as metabolites. Oral administration: Urinary excretion is 16% to 47% of the administered dose. 50% to 70% of colchicine is excreted unchanged, and 30% to 50% is excreted as metabolites. Within 24 hours of administration, 20% of the dose is excreted in the urine; within 48 hours, 27.5% is excreted in the urine. Colchicine can still be detected in urine 7 to 10 days after administration. Urinary excretion is increased in patients with impaired liver function. Bile: 10% to 25% of colchicine is excreted in the bile. Feces: A large amount of the drug is excreted in the feces. Breast milk: Colchicine may be excreted in breast milk. Intravenous injection: Feces: Within 48 hours after intravenous injection, 10% to 56% of the drug is excreted in the feces. Breast milk: Colchicine may be excreted in breast milk. Mechanism of action: Colchicine binds to tubulin, preventing its polymerization to form microtubules. This binding is reversible, and the half-life of the colchicine-tubulin complex is 36 hours. Colchicine impairs various cellular functions of microtubules: chromosome pair separation during mitosis (because colchicine arrests mitosis at metaphase), amoeba movement, and phagocytosis. Mitotic arrest can lead to diarrhea, bone marrow suppression, and hair loss. Colchicine may have direct toxic effects on muscles, the peripheral nervous system, and the liver. However, cellular function suppression cannot explain all-organ failure caused by severe colchicine overdose. Pharmacodynamics: Gout inflammation is triggered by urate crystals in tissues. These crystals are phagocytosed by neutrophils, but this leads to enzyme release and cell destruction. Chemokines are released and attract more neutrophils. The mechanism of action of colchicine may be through inhibition of phagocytosis, chemokine release, and neutrophil response. Colchicine also has other properties such as antipyretic, respiratory depression, vasoconstriction, and hypertension. Adults: Oral: The severity of poisoning and mortality are directly related to the ingested dose. Intravenous: A case of fatal bone marrow aplasia in a 70-year-old patient due to intravenous colchicine has been reported. The increased toxicity of colchicine administered intravenously may be due to its higher bioavailability after parenteral administration. Teratogenicity: Colchicine is contraindicated during pregnancy due to reports of Down syndrome and spontaneous abortion. Colchicine should be discontinued three months before conception. Drug Interactions: One case of acute cyclosporine nephrotoxicity caused by colchicine has been reported. Colchicine may increase plasma concentrations of cyclosporine by enhancing its absorption or reducing its hepatic metabolism, thereby interfering with its pharmacokinetics. Major Adverse Reactions: Gastrointestinal symptoms are a common complication of long-term colchicine use. There have been reports of death following intravenous colchicine administration. Gastrointestinal: Vomiting, diarrhea, abdominal discomfort, paralytic ileus, malabsorption syndrome with steatorrhea. Hematologic System: Myelosuppression with agranulocytosis, acute myeloid monocytic leukemia, multiple myeloma, thrombocytopenia. Nervous System: Peripheral neuritis, myopathy, and rhabdomyolysis. Skin: Allergic reactions are rare, but urticaria may occur; edema may also be seen. Hair loss has been reported after long-term treatment. Reproductive System: Reversible complete azoospermia has been reported. Metabolism: Colchicine can cause reversible impairment of vitamin B12 absorption. Late-onset porphyria has been reported. Other: A 58-year-old woman was reported to have developed hyperglycemia and transient diabetes after taking colchicine. Hyperlipidemia: Transient hyperlipidemia has been reported. Hyperuricemia: Transient hyperuricemia has also been reported. High Fever: Fever may be associated with infectious complications, especially during aplastic anemia. Special Risks: Pregnancy: Two cases of Down syndrome have been reported. Thirty-six women with familial Mediterranean fever were reported to have taken colchicine for 3 to 12 years, and their obstetric histories were documented. Seven of the 28 pregnancies ended in miscarriage. Thirteen women experienced infertility. All 16 infants born to mothers who took colchicine during pregnancy were healthy. The authors do not recommend discontinuing colchicine before planned pregnancy, but suggest amniocentesis for chromosomal karyotype analysis and to clear up any concerns. Lactation: Breastfeeding should be avoided as colchicine is excreted in breast milk.

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Drug Interactions
Colchicine has been shown to cause reversible malabsorption of vitamin B12, apparently by altering the function of the ileal mucosa.
Animal studies suggest that colchicine may enhance responses to sympathomimetic drugs and central nervous system depressants.
(1) Renal failure (whether pre-existing or caused by nephrotoxic drugs) increases the risk of adverse reactions in patients taking colchicine; (2) Colchicine-type drugs combined with macrolide antibiotics (except spiramycin) may cause life-threatening cytopenia; (3) Co-administration with cyclosporine may aggravate the neuromuscular adverse reactions of colchicine; (4) Co-administration of colchicine with lipid-lowering drugs (statins and fibrates) may cause myopathy; (5) Several mechanisms have been found to be associated with this: competition with cytochrome P450 or P-glycoprotein, additive adverse reactions (especially to muscles), and colchicine accumulation due to reduced renal excretion; (6) Colchicine should only be used in patients with gout after symptomatic treatment has failed. Symptomatic treatment includes ice packs, acetaminophen, and possibly ibuprofen (a nonsteroidal anti-inflammatory drug with well-established adverse reactions); (7) If colchicine is still necessary, the minimum effective dose should be used. Close clinical monitoring is required to detect signs of adverse reactions early, especially diarrhea, which is often the earliest symptom in patients with renal failure and in the elderly. Colchicine and 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors are both known to cause myopathy. The myotoxicity of both drugs is dose-related; therefore, symptoms often develop over months or years. We report a case of a patient with chronic renal failure who had been taking simvastatin for two years and developed acute myasthenia gravis two weeks after starting colchicine treatment for recurrent gout. Elevated electromyography and muscle enzymes suggested that the symptoms were caused by myopathy. The patient's myasthenia gravis symptoms rapidly subsided after discontinuation of both drugs. Acute myopathy caused by the combined use of colchicine and simvastatin is relatively rare. In patients with chronic renal failure, the combined use of colchicine and simvastatin may accelerate the development of myopathy because CYP3A4 (part of cytochrome P450) plays a crucial role in the metabolism of both drugs. For patients with renal insufficiency, if colchicine needs to be added to a treatment regimen containing an HMG-CoA reductase inhibitor, a drug metabolized outside the CYP3A4 system should be chosen (e.g., fluvastatin and pravastatin). For more complete data on drug interactions of colchicine (out of 13), please visit the HSDB record page. Non-human toxicity values: Cat intravenous LD50: 0.25 mg/kg; Mouse oral LD50: 5886 μg/kg; Mouse intraperitoneal LD50: 2 mg/kg; Mouse intravenous LD50: 4.13 mg/kg. For more complete data on non-human toxicity values of colchicine (out of 8), please visit the HSDB record page.

[1]. Colchicine induces apoptosis in cerebellar granule cells. Exp Cell Res. 1995 May;218(1):189-200.

[2]. Interactions of colchicine with tubulin. Pharmacol Ther. 1991;51(3):377-401.

[3]. Colchicine prevents NSAID-induced small intestinal injury by inhibiting activation of the NLRP3 inflammasome. Sci Rep. 2016 Sep 2;6:32587.

[4]. Inhibition of the Glycine Receptor alpha 3 Function by Colchicine. Front Pharmacol. 2020 Jul 30;11:1143.

Therapeutic Uses

Gout Inhibitors
Colchicine is also used to prevent recurrent gouty arthritis. Colchicine has no effect on plasma uric acid concentration or urinary excretion; therefore, it must be taken concurrently with allopurinol or a uricosuric agent (e.g., probenecid, sulfinpyrazone) to lower serum uric acid levels. A preventative dose of colchicine should be given before starting allopurinol or a uricosuric agent, as sudden changes in serum uric acid levels can trigger an acute gout attack. Colchicine can be discontinued once serum uric acid levels have decreased to the desired level and no acute gout attack has occurred for 3–6 months (some clinicians recommend 1–12 months), and the patient can be treated with uric acid-lowering medication alone. Colchicine is often used in combination with probenecid for the preventative treatment of chronic gouty arthritis. However, the efficacy of commercially available fixed-dose formulations is limited because they contain more colchicine than most patients require. /Directions for Use on US Product Label/
Colchicine is used to relieve acute gouty arthritis attacks. Nonsteroidal anti-inflammatory drugs (NSAIDs) (e.g., indomethacin, ibuprofen, naproxen, sulindac, piroxicam, ketoprofen) are comparable in efficacy to commonly used doses of colchicine in the short-term relief of acute gouty arthritis attacks, and are better tolerated. Corticosteroids are also used to relieve acute gouty arthritis attacks. Colchicine is considered a second-line treatment; it can be used to treat patients with acute gouty arthritis who are unresponsive to or cannot tolerate recommended therapies (e.g., NSAIDs, corticosteroids). /Usage included in the US product label/
This study included 96 patients aged 15 years and older with complete or incomplete Behcet's disease, whose visual acuity was 20/40 or lower, and who had experienced at least two ocular attacks within 16 weeks prior to the start of the study. 47 patients received cyclosporine (10 mg/kg) daily, and 49 patients received colchicine (1 mg/kg) daily for 16 weeks. The frequency of ocular seizures was significantly lower in the cyclosporine group than in the colchicine group (p < 0.001). The severity of ocular seizures was also lower after cyclosporine treatment than after colchicine treatment (p < 0.001). Colchicine relieved oral ulcers in 10 patients (20%). Skin lesions were relieved in 15% of patients in the colchicine group. Clinical symptoms improved in 33% of patients in the colchicine group, while symptoms worsened in 10 patients. The OKT4/OKT8 ratio was 1.44 before the study and 1.46 after treatment in the colchicine group. Common side effects of colchicine included hirsutism (2 cases) and renal dysfunction (2 cases). Two patients discontinued treatment due to liver dysfunction.
For more complete data on the therapeutic uses of colchicine (11 in total), please visit the HSDB record page.

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Drug Warning
Colchicine injection has been marketed in the United States since the 1950s for the treatment of acute gout attacks. None of the commercially available colchicine injections have been approved by the U.S. Food and Drug Administration (FDA). Patients receiving colchicine injections have reported serious adverse events, some of which have resulted in death. Given the potential serious health risks posed by unapproved colchicine injections, the FDA announced on February 8, 2008, that it would take enforcement action (e.g., seizure, injunction, or other legal proceedings) against any company (including dispensing pharmacies) attempting to manufacture, ship, or deliver colchicine injections. Effective February 8, 2008, the FDA will take enforcement action against any company attempting to manufacture or ship colchicine injection products without a National Drug Code (NDC) number. For colchicine injection products that have already obtained NDC numbers, the FDA will take enforcement action against all companies attempting to manufacture such products starting March 10, 2008, and those shipping such products starting August 6, 2008.
Therapeutic doses of colchicine have been reported to cause bone marrow suppression, leukopenia, granulocytopenia, thrombocytopenia, pancytopenia, and aplastic anemia.
Prolonged use of therapeutic doses of colchicine has been reported to cause neuromuscular toxicity and rhabdomyolysis. Patients with renal insufficiency and the elderly, even with normal renal and hepatic function, are at increased risk.
The most common adverse reaction is diarrhea (23%). Sore throat occurred in 3% of patients receiving treatment for acute gout attacks. Gastrointestinal adverse reactions are the most common side effects in patients taking colchicine, usually occurring within 24 hours, with an incidence of up to 20% in patients receiving therapeutic doses. Typical symptoms include cramps, nausea, diarrhea, abdominal pain, and vomiting. If these adverse reactions are severe, they should be considered dose-limiting factors, as they may foreshadow more serious toxicities. For more complete data on drug warnings for colchicine (13 in total), please visit the HSDB record page. Pharmacodynamics: Colchicine can relieve symptoms of gout and familial Mediterranean fever. It has anti-inflammatory, anti-fibrotic, and cardiovascular protective effects. Studies have shown that colchicine has anticancer properties, such as inhibiting cancer cell migration and angiogenesis. Colchicine has a narrow therapeutic window. The inflammasome is a large multiprotein complex composed of a nucleotide-binding oligomerization domain-like receptor (NLR), an apoptosis-associated speckle-like protein containing a caspase recruitment domain, and precursor caspase-1. Activation of the inflammasome leads to the cleavage of precursor caspase-1 into cleaved caspase-1, which in turn promotes the processing of pre-interleukin (IL)-1β into mature IL-1β. We investigated the effects of colchicine on NSAID-induced small intestinal injury and NLR family pyridine domain protein 3 (NLRP3) inflammasome activation. Colchicine treatment inhibited indomethacin-induced small intestinal injury, with an inhibition rate of 86% at 1 mg/kg and 94% at 3 mg/kg (based on the injury index 24 hours after indomethacin administration). Colchicine inhibited the protein expression of cleaved caspase-1 and mature IL-1β, but did not affect the mRNA expression of NLRP3 and IL-1β. Although recombinant IL-1β treatment (0.1 μg/kg) did not alter the severity of small intestinal injury, supplementation with the same dose of recombinant IL-1β negated the preventive effect of colchicine. In NLRP3(-/-) mice, indomethacin-induced small intestinal damage was reduced by 77% (indicating an injury index), while colchicine treatment failed to inhibit small intestinal damage in NLRP3(-/-) mice. These results suggest that colchicine prevents NSAID-induced small intestinal damage by inhibiting the activation of the NLRP3 inflammasome. [3]

C22H25NO6

399.44

399.168

C, 66.15; H, 6.31; N, 3.51; O, 24.03

64-86-8

Colchicine-d6;1217651-73-4;Colchicine-d3;1217625-62-1

6167

White to light yellow solid powder

1.3±0.1 g/cm3

726.0±60.0 °C at 760 mmHg

150-160 °C (dec.)(lit.)

392.9±32.9 °C

0.0±2.4 mmHg at 25°C

1.585

0.92

1

6

5

29

740

1

O(C([H])([H])[H])C1C(=C(C([H])=C2C=1C1=C([H])C([H])=C(C(C([H])=C1[C@]([H])(C([H])([H])C2([H])[H])N([H])C(C([H])([H])[H])=O)=O)OC([H])([H])[H])OC([H])([H])[H])OC([H])([H])[H]

IAKHMKGGTNLKSZ-INIZCTEOSA-N

InChI=1S/C22H25NO6/c1-12(24)23-16-8-6-13-10-19(27-3)21(28-4)22(29-5)20(13)14-7-9-18(26-2)17(25)11-15(14)16/h7,9-11,16H,6,8H2,1-5H3,(H,23,24)/t16-/m0/s1

N-[(7S)-1,2,3,10-tetramethoxy-9-oxo-6,7-dihydro-5H-benzo[a]heptalen-7-yl]acetamide

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: 2.78 mg/mL (6.96 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication (<60°C).

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 (Please use freshly prepared in vivo formulations for optimal results.)