In a dose-dependent manner, citric acid (0–12.5 mM; 24 hours) exhibits antiproliferative activity [3]. In G2/M and S phases, citric acid (12.5 mM; 72 h) dose-dependently induces apoptosis and cell cycle arrest [3]. The expression of FAS, BAX, BID, AIF, EndoG, cytochrome c, PARP, GADD153, GRP78, and caspase-3, -8, and -9 was increased and that of BCL-2 and BCL - Xl was decreased when exposed to 12.5 mM of citric acid for 48 hours[3].

Citric acid (120, 240, and 480 mg/kg; intraperitoneal injection) can significantly reduce GSH-Px activity and induce an increase in MDA (malondialdehyde) levels in mouse livers [1]. Citric acid (120, 240, and 480 mg/kg; i.p.) promotes apoptosis by raising caspase-3 activity in mouse hepatocytes in a dose-dependent manner [1]. ?Citric acid (120, 240, and 480 mg/kg; intraperitoneal injection; once weekly for 3 weeks) produces nephrotoxicity in mice [2].

Cell Viability Assay[3]
Cell Types: HaCaT Cell
Tested Concentrations: 0, 2.5, 5, 7.5, 10, 12.5 mM
Incubation Duration: 24 hrs (hours)
Experimental Results: Inhibition of cell viability in a dose-dependent manner.

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Cytotoxicity assay [3]
Cell Types: HaCaT Cell
Tested Concentrations: 12.5 mM
Incubation Duration: 0, 12, 24, 48, 72 h
Experimental Results: Induced apoptosis and cell cycle arrest in G2/M phase and S in a dose-dependent manner Expect.

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Western Blot Analysis[3]
Cell Types: HaCaT Cell
Tested Concentrations: 12.5 mM
Incubation Duration: 12, 24, 48 hrs (hours)
Experimental Results: Increased expression of FAS, BAX, BID, AIF, EndoG, cytochrome c, PARP, GADD153, GRP78 and caspase -3, -8, -9, and BCL-2 and BCL-X1 were diminished.

Animal/Disease Models: 20 g male Kunming mice [2]
Doses: 120, 240, 480 mg/kg
Route of Administration: intraperitoneal (ip) injection; once a week for 3 weeks.
Experimental Results: The activities of T-SOD and GSH-Px in the treatment group diminished with the increase of citric acid dose, the activity of NOS demonstrated an increasing trend, and the contents of H2O2 and MDA gradually diminished.

Absorption, Distribution and Excretion
A portion of circulating citric acid (primarily from metabolism, but also from intake) is excreted in urine. The 24-hour urine reference value ranges from 1.5 to 3.68 mmol, equivalent to 0.29 to 0.71 grams of citric acid excreted per person per day. Metabolism/Metabolites Citric acid is a normal metabolite and an intermediate product of cellular oxidative metabolism… This acid is formed in the mitochondria by the condensation of acetic acid and oxaloacetic acid. The hexacarbonate is then progressively degraded into a series of tetracarbonates, effectively completing the intracellular oxidation of acetic acid. In human (and animal and plant) physiology, citric acid is a very common intermediate in one of the core biochemical cycles—the Krebs cycle (or tricarboxylic acid cycle), which occurs in every cell. It completes the breakdown of pyruvate, produced from glucose via glycolysis, releasing carbon dioxide and four additional hydrogen atoms, which are then absorbed by electron-transfer molecules. Therefore, approximately 2 kilograms of citric acid are generated and metabolized in the human body daily. This physiological pathway is highly developed and capable of processing large amounts of citric acid, provided the concentration is low. Citric acid reacts with citrate lyase (citrate lyase) to produce oxaloacetic acid and acetic acid.

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
There is currently no data on the use of cellulose and citric acid during lactation. However, this medication is not absorbed by the gastrointestinal tract and therefore does not enter breast milk. Use of cellulose and citric acid during lactation is acceptable.
◉ Effects on Breastfed Infants
No published information found as of the revision date.
◉ Effects on Lactation and Breast Milk
No published information found as of the revision date.

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Interactions
…Inhalation of citric acid aerosol leads to a decrease in dynamic respiratory compliance and forced expiratory volume in 0.1 seconds (FEV0.1). MK-886, mepiquat, sodium cromoglycate, and compound 48/80 significantly reduced this airway constriction, while mesimergot and indomethacin did not. Both LTC4 and histamine infusion significantly enhanced citric acid-induced airway constriction in guinea pigs pretreated with compound 48/80. Inhalation of citric acid significantly increased histamine levels in bronchoalveolar lavage fluid samples, while compound 48/80 significantly inhibited this increase. The relative potency of citric acid, malic acid, malonic acid, oxalic acid, succinic acid, and deferoxamine mesylate in the toxicity, distribution, and excretion of aluminum-exposed mice was compared. Chelating agents were administered intraperitoneally at one-quarter of their respective LD50. To determine the effects of various chelating agents on aluminum toxicity, different doses of aluminum nitrate (938–3188 mg/kg) were administered intraperitoneally, followed by an injection of a chelating agent. Survival was recorded after 14 days. …Malic acid and deferoxamine mesylate were most effective in increasing urinary aluminum excretion. Citric acid was most effective in increasing fecal aluminum excretion. Malonic acid, oxalic acid, and succinic acid had no overall beneficial effect. Of all the reagents tested, citric acid appeared to be the most effective in preventing acute aluminum poisoning. ...When mice were simultaneously orally administered aluminum hydroxide and citric acid (133 mg Al/kg and 62 mg/kg, respectively), fetal skeletal developmental defects were induced. The primary objective of this study was to determine the relative effectiveness of various methods in monitoring aluminum load in weaned rats. These rats were fed different doses of aluminum (0.39 μmol A/g diet for 29 days; approximately 40 μmol A/g diet, with or without citrate, for 29 days; and approximately 100 μmol A/g diet, with citrate, for 12 or 29 days) or intraperitoneally injected with different doses of aluminum (0.01, 4.6, 11.8, 23.5, or 94 μmol A). All rats were intraperitoneally injected with deferoxamine (75 mg) or a buffer solution 24 hours before sacrifice. All seven monitored aluminum exposure parameters (e.g., tibial, liver, kidney, and serum aluminum concentrations; changes in serum aluminum concentration induced by deferoxamine; urinary aluminum excretion before and after deferoxamine treatment) were highly correlated with parenteral aluminum exposure (p < 0.001). Citrate intake had a small but significant effect on aluminum retention. /Citrate/
For more complete data on interactions of citric acid (7 items), please visit the HSDB record page.

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Non-human toxicity values
Oral LD50 in rats: 3000 mg/kg; 12000 mg/kg; 11700 mg/kg /Observed in independent experiments/
Oral LD50 in rats 6730 mg/kg
Intravenous LD50 in mice 42 mg/kg /From table/
Oral LD50 in mice 5040 mg/kg /From table/
For more complete data on non-human toxicity values of citric acid (10 items), please visit the HSDB record page.

[1]. Study on injury effect of food additive citric acid on liver tissue in mice. Cytotechnology. 2014 Mar;66(2):275-82.

[2]. Chen X, Lv Q, Liu Y, Deng W. Effects of the food additive, citric acid, on kidney cells of mice. Biotech Histochem. 2015 Jan;90(1):38-44.

[3]. Citric acid induces cell-cycle arrest and apoptosis of human immortalized keratinocyte cell line (HaCaT) via caspase- and mitochondrial-dependent signaling pathways. Anticancer Res. 2013 Oct;33(10):4411-20.

Therapeutic Uses
MeSH Title: Anticoagulants, Chelating Agents
/EXPL THER/ Regional citrate anticoagulation (RCA) is an effective anticoagulation method for patients undergoing continuous renal replacement therapy (CRRT) who are contraindicated for heparin. Its application is very limited, possibly due to the need for specialized infusion solutions and the difficulty in monitoring metabolic effects. /The purpose of this study/ To investigate the safety and feasibility of RCA using commercially available replacement solutions for continuous venous-venous hemofiltration (CVVH). We evaluated 11 patients at high bleeding risk who required CVVH. RCA was performed using commercially available replacement solutions to maintain adequate acid-base balance. We adjusted the citrate infusion rate to ensure that the post-filtration ionized calcium concentration [iCa] was <0.4 mmol/L at blood flow rates <250 mL/min and <0.6 mmol/L at blood flow rates >250 mL/min. Calcium gluconate was infused as needed to maintain systemic plasma [iCa] within the normal range. The 29 filters operated for a total of 965.5 hours. The average filter life was 33.6 ± 20.5 hours. Asymptomatic hypocalcemia was detected in 6.9% of all samples. No [iCa] values <0.9 mmol/L were observed. Hypercalcemia (1.39 ± 0.05 mmol/L) occurred in 2.5% of all samples. The authors observed that hypernatremia (threshold 153 mmol/L) and alkalosis (threshold 7.51) occurred in only 9.3% and 9.4% of all samples, respectively, and these often occurred simultaneously. No patients showed signs of citrate toxicity. They developed a protocol for RCA during CVVH using a commercially available replacement fluid, which proved safe, flexible, and suitable for the intensive care unit (ICU) environment. It has been used to dissolve bladder stones and as a mild astringent.
Citrates are valuable in relieving chronic metabolic acidosis, particularly that caused by chronic renal insufficiency or renal tubular acidosis syndrome, and are typically prescribed in the form of sodium citrate and citrate solution (USP).
Potassium citrate at doses up to 10 grams daily has been used as a potassium supplement; potassium and sodium salts have been used in similar doses as mild diuretics in humans.
Drug Warnings

A study on the severity of abdominal pain and other side effects caused by Picolax (a combination of citrate, magnesium oxide, and sodium picosulfate) was conducted in 267 patients, 55 of whom had inflammatory bowel disease. All patients received a single full dose of Picolax as preparation for radiology or endoscopy. The frequency of exacerbated abdominal pain and serious side effects was similar in patients with inflammatory bowel disease and other colonic diseases following Picolax administration. No serious side effects were reported in patients with iron deficiency who had negative test results; this is significantly different from the proportion of serious side effects reported in patients with inflammatory bowel disease, irritable bowel syndrome, and diverticulosis. The increase in average bowel movement frequency within 24 hours after Picolax administration was lower in patients with inflammatory bowel disease than in other diagnostic groups. No symptom worsening was reported in any of the inflammatory bowel disease patients during follow-up examinations 2–4 weeks after the initial examination. Following the development of aluminum encephalopathy in 4 patients with chronic renal failure, a study was conducted on 34 patients with azotemia who presented in the same year and 5 volunteers who received different combinations of aluminum hydroxide and alkalized citrate (Shohl's) solution. The study found that the four patients with encephalopathy were all older than the 34 patients with azotemia (68 ± 14 years, compared to 50 ± 13 years for azotemia patients, p < 0.05), had higher mean serum aluminum levels (727 μg/L ± 320, compared to 92 μg/L ± 73 for azotemia patients, p < 0.005), used more aluminum hydroxide (5 g/day ± 0.9, compared to 1.6 g/day ± 1.8 for azotemia patients, p < 0.01), and used more Shohl's solution (64 ml/day ± 19, compared to 20 ml/day ± 29 for azotemia patients, p < 0.01). In all 38 patients, serum aluminum levels were positively correlated with age (p = 0.01), aluminum hydroxide dosage (p = 0.001), and concurrent citrate administration (p = 0.004). In five healthy volunteers, 24-hour urinary aluminum excretion increased from a baseline of 22 μg ± 19 (standard deviation) to 167 μg ± 109 during aluminum hydroxide intake (p = 0.05), and further increased to 580 μg ± 267 (p = 0.01) after concurrent intake of citrate and aluminum hydroxide. The corresponding serum aluminum levels were 11 μg/L ± 2 (standard deviation), 44 μg/L ± 34 (p = 0.1), and 98 μg/L ± 58 (p < 0.05), respectively. Therefore, citrate appears to enhance aluminum absorption and may contribute to encephalopathy in patients with chronic renal failure, particularly the elderly.

C6H8O7

192.1235

192.027

77-92-9

Lithium citrate tetrahydrate;6080-58-6;Citric acid triammonium;3458-72-8;Sodium citrate dihydrate;6132-04-3;Citric acid trisodium;68-04-2;Citric acid monohydrate;5949-29-1;Ferric citrate;3522-50-7;Citric acid-d4;147664-83-3;Citric acid-13C6;287389-42-8;Hydroxycitric acid tripotassium hydrate;6100-05-6;Citric acid-13C3;302912-06-7

311

White to off-white solid powder

1.8±0.1 g/cm3

309.6±42.0 °C at 760 mmHg

153-159 °C(lit.)

155.2±24.4 °C

0.0±1.5 mmHg at 25°C

1.575

-1.72

4

7

5

13

227

0

KRKNYBCHXYNGOX-UHFFFAOYSA-N

InChI=1S/C6H8O7/c7-3(8)1-6(13,5(11)12)2-4(9)10/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12)

2-hydroxypropane-1,2,3-tricarboxylic acid

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)

H2O : ~100 mg/mL (~520.51 mM)
DMSO : ~100 mg/mL (~520.51 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (13.01 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (13.01 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (13.01 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 100 mg/mL (520.51 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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