CA IX/carbonic anhydrase (IC50 = 30 nM)

Acetazolamide likewise suppresses hCA II with an IC50 of 130 nM [1]. Acetazolamide (Ace) is a heteroaryl starch amide that is tiny and has a high affinity for several biocyclic enzymes. It can be utilized as a dye for biocyclic amylase (CA). The Hep Vitality - 2 cells was dramatically reduced when low-concentration sodium acetazolamide (AceL, 10 nM) was mixed with high-concentration sodium acetazolamide (AceH, 50 nM), cisplatin (Cis; 1 μg/mL), and Cis in comparison to loading[2]. When compared to tomorrow, the Acetazolamide/Cis combination treatment significantly increased P53 expression levels, as AceL+Cis and AceH+Cis treatments also resulted in a significant increase in P53 expression levels. Additionally, the Ace/Cis combined treatment significantly reduced the expression of bcl-2/bax and increased the expression of caspase-3 protein. Ace and Cis together can efficiently increase Hep-2 cells. AceL, AceH, Cis, and AceL+Cis therapy dramatically lowered bcl-2 when compared with monitoring [2]. When Ace and Cis are used together, AQP1 mRNA expression in Hep-2 cells can be greatly decreased. Both AceH and AceL+Cis treatments decreased the expression of aquaporin 1 (AQP1) mRNA in Hep-2 cells as compared to the laboratory [2].

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Acetazolamide (AZ) , MS-275 and AZ + MS-275 treatments inhibit growth of NB SH-SY5Y cells. AZ, MS-275 and AZ + MS-275 treatments reduced migration capacity in NB SH-SY5Y cells. Results: We evaluated the antitumor potential of the HDAC inhibitor (HDACi), pyridylmethyl-N-{4-[(2-aminophenyl)-carbamoyl]-benzyl}-carbamate (MS-275) in combination with a pan CA inhibitor, acetazolamide (AZ) on NB SH-SY5Y, SK-N-SH and SK-N-BE(2) cells. The key observation was that the combination AZ + MS-275 significantly inhibited growth, induced cell cycle arrest and apoptosis, and reduced migration capacity of NB cell line SH-SY5Y. [2]

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The aim of the present study was to determine whether acetazolamide (Ace) treatment enhances the chemosensitivity of Hep-2 laryngeal cells to cisplatin (Cis). At the logarithmic growth phase, Hep-2 cells were treated with Ace, Cis or both, and cell viability was detected using an MTT assay. The degree of apoptosis was detected using flow cytometry. Expression levels of apoptosis-related proteins, including BCL2 apoptosis regulator (bcl-2), BCL2 associated X (bax) and caspase-3, and of proliferation-related proteins, including proliferating cell nuclear antigen (PCNA) and tumor protein p53 (P53), were detected using western blotting. mRNA expression levels of aquaporin-1 (AQP1) in each group were detected using reverse transcription-polymerase chain reaction. Compared with the drugs used alone, treatment with both Ace and Cis displayed synergistic effects on the growth inhibition and apoptosis induction in Hep-2 cells. The Ace/Cis combination decreased the expression of PCNA but increased the expression of p53. In addition, the combination treatment decreased the ratio of bcl-2/bax and increased the expression of caspase-3, as well as decreased the expression of AQP1. These results demonstrated that the combined use of Ace and Cis enhanced the chemosensitivity of laryngeal carcinoma cells.[3]

Acetazolamide (40 mg/kg) significantly increased the inhibitory impact of MS-275 on tumorigenesis of neuroblastoma (NB) SH-SY5Y xenografts [3]. Sodium acetazolamide (40 mg/kg) and/or MS-275. Acetazolamide (40 mg/kg), MS-275 and Acetazolamide+MS-275 diminish mitosis in NB SH-SY5Y xenografts and treatable reduction of HIF1-α and CAIX expression in NB SH-SY5Y xenografts [3]. Expression of edema markers [3]. Acetazolamide sodium (50 mg/kg; PO for 3 days) effectively lowers gonococcal load in infected oral cavity by 90% [6].

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Gonococcal infections represent an urgent public health threat worldwide due to the increasing incidence of infections that has been accompanied by an increase in bacterial resistance to most antibiotics. This has resulted in a dwindling number of effective treatment options. Undoubtedly, there is a critical need to develop new, effective anti-gonococcal agents. In an effort to discover new anti-gonococcal therapeutics, we previously identified Acetazolamide, a carbonic anhydrase inhibitor, as a novel inhibitor of Neisseria gonorrhoeae. Acetazolamide exhibited potent anti-gonococcal activity in vitro as it inhibited growth of strains of N. gonorrhoeae at concentrations that ranged from 0.5 to 4 μg/mL. The aim of this study was to investigate the in vivo efficacy of acetazolamide in a mouse model of N. gonorrhoeae genital tract infection. Compared to vehicle-treated mice, acetazolamide significantly reduced the gonococcal burden by 90% in the vagina of infected mice after three days of treatment. These results indicate that acetazolamide warrants further investigation as a promising treatment option to supplement the limited pipeline of anti-gonococcal therapeutics.[6]

AlamarBlue cytotoxicity assay [2]
Standard protocol was performed as describe. Percent survival vs. control (DMSO- 0.2x10−4μM) of cells when treated with Acetazolamide (AZ) , MS-275 and AZ + MS-275 were observed using AlamarBlue agent agent (10% of total volume) was added to each well for 4 h before fluorometric detection. Fluorescence was measured using the SPECTRAmax Gemini Spectrophotometer (excitation 540 nm; emission 590 nm).

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Propidium Iodide cell cycle assay [2]
Briefly, 2 × 106 cells treated with Acetazolamide (AZ) and/or MS-275 were lifted by citrate saline and fixed in 80% ice-cold ethanol for 48 h. Cells were then pelleted and re-suspended in 2 mg/mL RNase A for 5 min. A 0.1 mg/mL propidium iodide solution was added, incubated for 30 min at RT, and cells filtered through a cell-strainer into a 5 mL polystyrene tube. Labeled cells were analyzed on a BD FACSCAN flow cytometer. Data was fitted by the Watson-Pragmatic model on FlowJo Software.

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Wound healing assay [2]
SH-SY5Y cells were seeded in a 48-well plate on glass cover slips and allowed to adhere overnight at a density of 105 cells/well in 500 μl culture medium in triplicate. Wells were marked with a straight black line on the bottom for orientation. At the time of 90% confluence, cell monolayers were scratched with a 200 μl pipette tip using the marker guide. Loosened non-adherent cells were washed off with medium. Fresh medium was added to the cultures with additions of Acetazolamide (AZ) (10 μM, 20 μM, 40 μM) and MS-275 (0.75 μM, 1.5 μM and 3 μM) and cultured for 48 h. After the 48 h period cells were washed with PBS and fixed in 4% paraformaldehyde. After three washes in PBS, cells were stained with 1% Crystal violet in 20% methanol. Phase contrast light microscopic images (10x original magnification) were taken at time points of 0, 48 and 72 h of treatment. Migrated cells were counted manually to quantify numbers of cells migrated to wound area using NIH Image J program. Each experiment was conducted three times in triplicate and one representative assay is shown.

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For the drug treatments, Hep-2 cells were treated with Acetazolamide (ACE) (a low concentration of 1×10−8 mol/l, termed here Acetazolamide (ACE)L; or a high concentration of 5×10−8 mol/l, termed here AceH), Cis (1 µg/ml) alone, or Cis in combination with Ace (AceL+Cis, or AceH+Cis) for 48 h. Cells that were treated with equal volumes of vehicle were used as control. Ace was used at 1×10−8 or 5×10−8 mol/l in all experiments. Cis was used at 1 µg/ml in all experiments. Both Cis and Ace were dissolved in dimethyl sulfoxide (DMSO) and then added to PBS to dilute to the final working concentrations. The final concentration of DMSO in cultures did not exceed 0.5%. HUVECs were treated with AceH alone, Cis alone or in combination (AceH+Cis) or control (vehicle) for 48 h.[3]

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Annexin V apoptosis assay [3]
Quantification of apoptotic cells was performed by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double staining using a FITC-Annexin V Apoptosis Detection kit. At the logarithmic growth phase, Hep-2 cells were placed in 6-well plates. The cells were treated with Acetazolamide (ACE)L, AceH, Cis, AceL+Cis, AceH+Cis, or vehicle for 48 h. Then, cells were washed in PBS, digested with trypsin, and resuspended in calcium-enriched HEPES buffer. This suspension was stained with Annexin V-FITC and PI for 15 min, as per the manufacturer's instructions. Finally, the cells were analyzed by FlowJo software.

Xenograft studies for determining the in vivo efficacy of Acetazolamide (AZ) , MS-275, and Acetazolamide (AZ)  + MS-275 combination [2]
For the in vivo xenograft study, 4–6 weeks-old female NOD/SCID mice were obtained from the animal facility. Subcutaneous xenograft tumors were developed by injecting SH-SY5Y cells (2 × 106) into the inguinal fat pad of NOD/SCID mice. When tumor diameter reached 0.5 cm, the mice were randomized into four groups (5 mice per group). The control and treatment groups received intraperitoneal injections of vehicle (PBS) or Acetazolamide (AZ) (40 mg/kg), MS-275 (20 mg/kg) or the combination, respectively, every day for 2 weeks. Experiments were terminated when tumor sizes exceeded 2 cm3 in volume or animals showed signs of morbidity. Tumor diameters were measured on a daily basis until termination. The long (D) and short diameters (d) were measured with calipers. Tumor volume (cm3) was calculated as V = 0.5 × D × d2. After euthanizing the mice, tumors were resected, weighed and fixed in 10% neutral-buffered formalin at room temperature and processed for histopathology. For the in vivo serial heterotransplantation analysis, 2x106 untreated and pretreated Acetazolamide (AZ)  + MS-275 cells, manually and enzymatically dissociated from treated tumors, were injected subcutaneously to NOD/SCID mice. Growth rates were measured 2–3 times per week. On the 38th day, the animals were sacrificed, after which tumors were removed and weighed.

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Mice infection and treatment [6]
Two days after pellet implantation (Day 0), the vagina of each mouse was rinsed with 50 mM HEPES (pH = 7.4), and each mouse was inoculated intravaginally with 20 μL of the prepared bacterial suspension of N. gonorrhoeae FA1090 (1.2 × 108 CFU/mL). Two days post-infection (Day +2), mice were randomly allocated into groups (n=10) and administered either Acetazolamide (50 mg/kg) or the vehicle (DMSO-Tween 80-PBS, 1:1:8) orally for three consecutive days. As a positive control, one group of mice was administered a single intraperitoneal dose of ceftriaxone (15 mg/kg in water).

Absorption, Distribution and Excretion
Carbonic anhydrase inhibitors are avidly bound by carbonic anhydrase and, accordingly, tissues rich in this enzyme will have higher concentrations of carbonic anhydrase inhibitors following systemic administration. /Carbonic Anhydrase Inhibitors/
Inhibitors of Carbonic Anhydrase. Drug: acetazolamide; Oral Absorption: nearly complete; Plasma Half-Life: 6-9 hours; and Route of Elimination: renal excretion of intact drug. /From table/
ACETAZOLAMIDE RELATED TO RESPONSE IN RABBIT; KIDNEY RESPONSE, MEASURED BY MONITORING URINE FLOW & NA ELIMINATION, URINE FLOW & NA ELIMINATION OCCUR IMMEDIATELY AFTER INJECTION CORRELATED WITH LOG DOSE.
IV BOLUS INJECTIONS OF (14)C-LABELED, ACETAZOLAMIDE WERE MADE IN RABBITS. PLASMA, URINE, & WASHED RED BLOOD CELL CONCN WERE MEASURED, THE LATTER INDICATING BOUND DRUG.
For more Absorption, Distribution and Excretion (Complete) data for ACETAZOLAMIDE (6 total), please visit the HSDB record page.

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Metabolism / Metabolites
ACETAZOLAMIDE DOSE NOT UNDERGO METABOLIC ALTERATION.

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Biological Half-Life
3 to 9 hours
Plasma half-life: 6-9 hours /From table/

Toxicity Summary
IDENTIFICATION: Acetazolamide is of synthetic origin. Acetazolamide exists as a white to faintly yellowish-white, odorless crystalline powder. Acetazolamide is very slightly soluble in water and only slightly soluble in ethanol (approx 750 g/l); it is practically insoluble in ether and chloroform. Uses: Preoperative management of closed-angle glaucoma, or as an adjunct in the treatment of open-angle glaucoma. Abnormal retention of fluid: drug-induced edema, obesity, and congestive cardiac failure. Epilepsy Metabolic alkalemia. Periodic paralysis HUMAN EXPOSURE: Patients with either acute or chronic overdosage with acetazolamide may show signs of dehydration with thirst, lethargy, confusion, poor skin turgor, and prolonged capillary refill time, but may have a paradoxical continued diuresis. Electrolyte abnormalities include hyponatremia, hypokalemia, and a non-anion gap hyperchloremic metabolic acidosis in the more than mild ingestion which may lead to further deterioration in mental status, production of seizures, electrocardiographic abnormalities, and arrhythmias. Prior renal insufficiency will lead to increased toxicity at a given dose. There are idiosyncratic reactions producing bone marrow suppression with hepatic and renal insufficiency. Acetazolamide may also precipitate in the renal tubules producing calculi with renal colic. Hypokalemia may lead to muscular weakness, hyporeflexia, and hypochloremic metabolic alkalosis. In geriatric patients, a chronic metabolic acidosis may lead to a chronic compensatory hyperventilation which increases pulmonary vascular resistance and decreases left ventricular function. This can be especially significant in patients on concurrent beta-blocker or calcium channel blocker therapy. The ventricular fibrillation threshold may then be reduced. Cardiac arrhythmias may occur due to potassium deficiency. Abuse or overdose may result in pancreatitis. Hyperglycemia, hyperuricemia, and hyperlipidemia may occur with acute overdose or in chronic use or abuse. Hypersensitivity reactions such as rash, photosensitivity, thrombocytopenia, and pancreatitis are rare. Contraindications: Renal hyperchloremic acidosis. Addison's disease and all types of suprarenal gland failure. Conditions where there is known depletion of sodium and potassium (at least until this is treated). Long-term administration is contraindicated in patients with chronic closed angle-closure glaucoma. Known sensitivity to sulfonamides. Acetazolamide should not be used to alkalinize urine following salicylate overdose since it may worsen metabolic acidosis. Acetazolamide is well absorbed from the gastrointestinal tract. Acetazolamide is distributed throughout body tissues; it concentrates principally in erythrocytes, plasma and kidneys and to a lesser extent in liver, muscles, eyes and the central nervous system. Acetazolamide does not accumulate in tissues. The drug crosses the placenta in unknown quantities. Acetazolamide is tightly bound to carbonic anhydrase and high concentrations are present in tissues containing this enzyme such as erythrocytes and the renal cortex. There is a small amount of irreversible binding to red cells. It is 70 to 90% bound to plasma protein. Acetazolamide is not metabolized. Acetazolamide is excreted unchanged by the kidneys via tubular secretion and passive reabsorption. There is no evidence of enterohepatic circulation although small amounts of unchanged drug are eliminated in the bile. Acetazolamide is a carbonic anhydrase inhibitor. Acetazolamide reduces the formation of hydrogen and bicarbonate ions from carbon dioxide and water by noncompetitive, reversible inhibition of the enzyme carbonic anhydrase, thereby reducing the availability of these ions for active transport into secretions. One patient died of cholestatic jaundice after taking 13 g of acetazolamide in 26 days. In one patient, fatal bone marrow depression with leukopenia, thrombocytopenia, and anemia occurred after therapy with 500 mg of acetazolamide twice daily for 14 weeks. One case of renal failure (anuria) occurred in a patient after taking 500 mg of acetazolamide twice daily for 2 weeks. There have been no reports of congenital defects despite past widespread use though one women on 750 mg per day for glaucoma during the 1st and 2nd trimester had a baby with a sacrococcygeal teratoma but no causal link could be made. Teratogenicity tests in rats and mice showed the absence of fourth and fifth digits from the right forelimb in the offspring of rats and mice. There were no apparent lessions in the newborn of rabbits and monkeys. The drug crosses the placenta in unknown quantities. Potentially hazardous interactions: The effects of folic acid antagonists, oral hypoglycaemic agents and oral anticoagulants may be increased by acetazolamide. The urinary antiseptic effect of methenamine may be prevented by acetazolamide by keeping the urine alkaline. The alkalinization of the urine by acetazolamide can reduce the urinary excretion of many weak bases (including amphetamine, quinine, quinidine, and diethylcarbamazine) and thus enhance their pharmacological effects. In one patient taking phenytoin and acetazolamide drug-induced osteomalacia was reported. The more serious effects include blood disorders, skin toxicity and renal stone formation. Stevens-Johnson syndrome has not been reported. Symptomatic adverse effects: Flushing, thirst, headache, drowsiness, dizziness, fatigue, irritability, excitement, paresthesias, ataxia, hyperpnoa and gastrointestinal disturbances have all been reported (Dollery). Oral ingestion is the usual means of exposure. There is no appreciable dermal absorption. There is no significant absorption or local irritation. ANIMAL/PLANT STUDIES: Numerous animal studies have demonstrated that the toxicity of acetazolamide was very low in the species studied (mouse, dog, rat, monkey). International Programme on Chemical Safety; Poisons Information Monograph: Acetazolamide (PIM 005) (1995) Available from, as of May 16, 2008: https://www.inchem.org/pages/pims.html

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Limited information indicates that maternal doses of acetazolamide up to 1000 mg daily produce low levels in milk and would not be expected to cause any adverse effects in breastfed infants. American, Canadian and French professional guidelines consider carbonic anhydrase inhibitors acceptable in breastfeeding.
◉ Effects in Breastfed Infants
A breastfed (extent not stated) infant whose mother was taking sustained-release acetazolamide (Diamox Sequels) 500 mg twice daily exhibited no apparent adverse effects related to acetazolamide from day 6 to day 10 postpartum.
A mother who was taking acetazolamide 250 mg orally twice daily as well as using 2 drops of timolol 0.5% eye drops daily and pilocarpine eye drops twice daily delivered a preterm infant at 36 weeks of gestation. The infant began 5 months of exclusive breastfeeding at 6 hours after birth. On day 2, the infant developed electrolyte abnormalities consisting of hypocalcemia, hypomagnesemia, and metabolic acidosis. The infant was treated with oral calcium gluconate and a single dose of intramuscular magnesium sulfate. Despite continued breastfeeding and maternal drug therapy, the infant's mild metabolic acidosis resolved on day 4 of life and the infant was gaining weight normally at 1, 3 and 8 months, but had mild hypotonicity. The authors considered the metabolic effects to be caused by transplacental passage of acetazolamide that resolved despite the infant being breastfed. The infant gained weight adequately during breastfeeding, but had some mild, residual hypertonicity of the lower limbs requiring physical therapy.
Two women were receiving acetazolamide during pregnancy and postpartum for pseudotumor cerebri. Their infants had metabolic acidosis after birth. Both infants resolved their metabolic acidosis despite receiving maternal breastmilk.
◉ Effects on Lactation and Breastmilk
A randomized, partially blinded trial compared acetazolamide 1 tablet (presumably 250 mg) by mouth daily, diethylstilbestrol 0.5 mg twice daily, placebo once daily and routine care in 243 mothers who wished to not breastfeed. Pain and breast fullness were assessed at least daily by blinded observers. In this dosage, acetazolamide was no more effective than placebo and somewhat less effective than diethylstilbestrol in relieving discomfort.

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Protein Binding
98%

[1]. Acetazolamide potentiates the anti-tumor potential of HDACi, MS-275, in neuroblastoma. BMC Cancer. 2017 Feb 24;17(1):156.

[2]. Dual-tail approach to discovery of novel carbonic anhydrase IX inhibitors by simultaneously matching the hydrophobic and hydrophilic halves of the active site. Eur J Med Chem. 2017 May 26;132:1-10.

[3]. Combined treatment with acetazolamide and cisplatin enhances chemosensitivity in laryngeal carcinoma Hep-2 cells. Oncol Lett. 2018 Jun;15(6):9299-9306.

[4]. Acetazolamide: a forgotten diuretic agent. Cardiol Rev. 2011 Nov-Dec;19(6):276-8.

[5]. Interaction of antihypertensive acetazolamide with nonsteroidal anti-inflammatory drugs. J Photochem Photobiol B. 2013 Aug 5;125:155-63.

[6]. In vivo efficacy of acetazolamide in a mouse model of Neisseria gonorrhoeae infection. Microb Pathog. 2022 Mar;164:105454.

Acetazolamide sodium is an organic sodium salt. It contains an acetazolamide and an acetazolamide(1-).
Acetazolamide Sodium is the sodium salt of acetazolamide, a nonbacteriostatic sulfonamide derivative with diuretic and anticonvulsant properties. Acetazolamide is a potent inhibitor of carbonic anhydrase that plays an important role in the control of fluid secretion. Inhibition of this enzyme in the kidney results in a reduction in the availability of hydrogen ions for active transport in the renal tubule lumen, thereby leading to increased bicarbonate and cation excretion, and increased urinary volume. Reduced bicarbonate level in circulation induces reduction of intraocular pressure via osmotic mechanism. The anticonvulsant activity of acetazolamide may contribute to inhibition of carbonic anhydrase in the CNS, which decreases carbon dioxide tension in the pulmonary alveoli, thus increasing arterial oxygen tension.
See also: Acetazolamide (has active moiety).

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Acetazolamide can cause developmental toxicity according to state or federal government labeling requirements.
Acetazolamide appears as white to yellowish-white fine crystalline powder. No odor or taste. (NTP, 1992)
Acetazolamide is a sulfonamide, a member of thiadiazoles and a monocarboxylic acid amide. It has a role as a diuretic, an anticonvulsant and an EC 4.2.1.1 (carbonic anhydrase) inhibitor. It is a conjugate acid of an acetazolamide(1-). It derives from a hydride of a 1,3,4-thiadiazole.
One of the carbonic anhydrase inhibitors that is sometimes effective against absence seizures. It is sometimes useful also as an adjunct in the treatment of tonic-clonic, myoclonic, and atonic seizures, particularly in women whose seizures occur or are exacerbated at specific times in the menstrual cycle. However, its usefulness is transient often because of rapid development of tolerance. Its antiepileptic effect may be due to its inhibitory effect on brain carbonic anhydrase, which leads to an increased transneuronal chloride gradient, increased chloride current, and increased inhibition. (From Smith and Reynard, Textbook of Pharmacology, 1991, p337)
Acetazolamide is a Carbonic Anhydrase Inhibitor. The mechanism of action of acetazolamide is as a Carbonic Anhydrase Inhibitor.
Acetazolamide is a sulfonamide derivative with diuretic, antiglaucoma, and anticonvulsant properties. Acetazolamide is a non-competitive inhibitor of carbonic anhydrase, an enzyme found in cells in the proximal tube of the kidney, the eye, and glial cells. Inhibition of this enzyme in the kidney prevents excretion of hydrogen, leading to increased bicarbonate and cation excretion and increased urinary volume, which results in an alkaline diuresis. Acetazolamide reduces the concentration of bicarbonate, resulting in a decreased synthesis of aqueous humor in the eye, thereby lowering intraocular pressure. Although its mechanism of action is unknown, acetazolamide has anti-convulsant properties resulting from indirect effects secondary to metabolic acidosis or direct effects on neuronal transmission. Acetazolamide also produces respiratory stimulant effects in response to changes to both carbon dioxide and oxygen tension levels within the lungs.
One of the CARBONIC ANHYDRASE INHIBITORS that is sometimes effective against absence seizures. It is sometimes useful also as an adjunct in the treatment of tonic-clonic, myoclonic, and atonic seizures, particularly in women whose seizures occur or are exacerbated at specific times in the menstrual cycle. However, its usefulness is transient often because of rapid development of tolerance. Its antiepileptic effect may be due to its inhibitory effect on brain carbonic anhydrase, which leads to an increased transneuronal chloride gradient, increased chloride current, and increased inhibition. (From Smith and Reynard, Textbook of Pharmacology, 1991, p337)
See also: Acetazolamide Sodium (has salt form); Acetazolamide disodium (is active moiety of).

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Drug Indication
For adjunctive treatment of: edema due to congestive heart failure; drug-induced edema; centrencephalic epilepsies; chronic simple (open-angle) glaucoma
FDA Label

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Mechanism of Action
The anticonvulsant activity of Acetazolamide may depend on a direct inhibition of carbonic anhydrase in the CNS, which decreases carbon dioxide tension in the pulmonary alveoli, thus increasing arterial oxygen tension. The diuretic effect depends on the inhibition of carbonic anhydrase, causing a reduction in the availability of hydrogen ions for active transport in the renal tubule lumen. This leads to alkaline urine and an increase in the excretion of bicarbonate, sodium, potassium, and water.
Carbonic anhydrase inhibitors potently inhibit (IC50 for acetazolamide is 10 nM) both the membrane bound and cytoplasmic forms of carbonic anhydrase, resulting in nearly complete abolition of NaHCO3 reabsorption in the proximal tubule. /Carbonic Anhydrase Inhibitors/
Although the proximal tubule is the major site of action of carbonic anhydrase inhibitors, carbonic anhydrase also is involved in secretion of titratable acid in the collecting duct system (a process which involves a proton pump), and therefore the collecting duct system is a secondary site of action for this class of drugs. /Carbonic Anhydrase Inhibitors/
Acetazolamide frequently causes paresthesias and somnolence, suggesting an action of carbonic anhydrase inhibitors in the CNS. The efficacy of acetazolamide in epilepsy is in part due to the production of metabolic acidosis; however, direct actions of acetazolamide in the CNS also contribute to its anticonvulsant action.
... Inhibition of carbonic anhydrase decreases the rate of formation of aqueous humor and consequently reduce intraocular pressure. /Carbonic Anhydrase Inhibitors/
For more Mechanism of Action (Complete) data for ACETAZOLAMIDE (6 total), please visit the HSDB record page.

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Acetazolamide is the only carbonic anhydrase inhibitor with significant diuretic effects. It is readily absorbed and undergoes renal elimination by tubular secretion. Its administration is ordinarily marked by a brisk alkaline diuresis. Although carbonic anhydrase inhibitors are proximal tubular diuretics (where the bulk of sodium re-absorption occurs), their net diuretic effect is modest in that sodium re-absorption in more distal nephron segments offsets proximal sodium losses. Acetazolamide use is limited by both its transient action and the development of metabolic acidosis with extended administration. Acetazolamide can, however, correct the significant metabolic alkalosis which occasionally occurs with loop diuretic therapy.[3]

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The binding of antihypertensive acetazolamide with eleven nonsteroidal anti-inflammatory drugs (NSAIDs) was investigated at pH 3, 7 and 9.5 with the objective of monitoring their interactive pharmacokinetics during digestion and absorption in human body. The results of UV-Vis spectroscopy and cyclic voltammetry revealed two NSAIDs (acetaminophen and dichlofenic sodium) to interact with acetazolamide in stomach fluid conditions forming complexes of 1:1 and 1:2 stoichiometry. The complexation ratio was also verified by computational methods. The strong binding propensity of acetaminophen and dichlofenic sodium with acetazolamide prohibited their combined therapy. However, the poor binding affinity of aspirin and mefinamic acid suggested these drugs as preferred NSAIDs to be prescribed with acetazolamide.[4]

C4H5N4O3S2-.NA+

244.2273

243.97

1424-27-7

Acetazolamide;59-66-5;Acetazolamide-d3;1189904-01-5

13290219

White to off-white solid powder

258-259ºC (EFFERVESCENCE)

0.783

2

7

2

14

302

0

MRSXAJAOWWFZJJ-UHFFFAOYSA-M

InChI=1S/C4H6N4O3S2.Na/c1-2(9)6-3-7-8-4(12-3)13(5,10)11;/h1H3,(H3,5,6,7,9,10,11);/q;+1/p-1

sodium;(5-acetamido-1,3,4-thiadiazol-2-yl)sulfonylazanide

Acetazolamide sodium; Sodium acetazolamide; 1424-27-7; Acetazolamide sodium salt; CHEBI:31163; 429ZT169UH; sodium;(5-acetamido-1,3,4-thiadiazol-2-yl)sulfonylazanide; N-(5-Sulfamoyl-1,3,4-thiadiazol-2-yl)acetamide monosodium salt;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

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

H2O : ≥ 100 mg/mL (~407.76 mM)
DMSO : ~100 mg/mL (~407.76 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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