Lithostat (acetohydroxamic acid)

To obtain optimum results, patients should be given a copy of the patient information provided by the manufacturer. Patients should be advised of the importance of complying with the prescribed dosage regimen for acetohydroxamic acid, since failure to comply may result in decreased efficacy of the drug and recurrence of stone formation.

The optimum dose and frequency of administration of acetohydroxamic acid in patients with moderate degrees of renal impairment have not been determined. In patients with serum creatinine concentrations of 1.8-2.5 mg/dL, the manufacturer currently recommends that the total daily dose of acetohydroxamic acid not exceed 1 g, given in 2 divided doses at 12-hour intervals; however, pending further accumulation of data, some clinicians recommend that the drug be used with extreme caution in patients with a serum creatinine concentration of 1.3-2.5 mg/dL and that total daily dose also not exceed 1 g in patients with a serum creatinine concentration of 1.3-1.8 mg/dL. These clinicians also recommend that serum creatinine concentration be determined periodically and monitored closely during therapy with the drug in patients with renal impairment or changing renal function. Additional dosage reduction may be necessary to prevent the accumulation of toxic concentrations of the drug. The drug should not be administered to patients with serum creatinine concentration greater than 2.5 mg/dL or creatinine clearance less than 20 mL/minute. (See Cautions: Precautions and Contraindications.)

Acetohydroxamic acid is administered orally. Although the manufacturer states that acetohydroxamic acid should always be administered at a time when the stomach is empty, the effect of food on GI absorption of the drug has not been determined. Absorption of the drug may potentially be reduced by dietary metals (e.g., iron). (See Drug Interactions: Iron.)

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There are no contraindication interactions for this drug.

There are no severe interactions for this drug.

There are no moderate interactions for this drug.

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• Alcohol use disorder
• Chronic kidney disease stage 4 (severe) GFR 15-29 ml/min
• Chronic kidney disease stage 5 (failure) GFr<15 ml/min
• Pregnancy

• Chronic kidney disease stage 3A (moderate) GFR 45-59 ml/min
• Chronic kidney disease stage 3B (moderate) GFR 30-44 ml/min
• Phlebitis

• Anemia
• Hemolytic anemia
• Leukopenia
• Thrombocytopenic disorder

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More Frequent

• Acute cognitive impairment
• Depression
• Hemolytic anemia
• Nervousness
• Phlebitis
• Thrombotic disorder
• Tremor

More Frequent

• Anorexia
• Headache disorder
• Malaise
• Nausea
• Symptoms of anxiety
• Vomiting

Rare or Very Rare

• Alopecia
• Skin rash

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Acetohydroxamic acid may cause fetal harm when administered to pregnant women. The drug has been shown to be teratogenic in rats, causing retarded and/or clubbed rear leg, exencephaly, encephalocele, cleft palate, and ectrodactyly and polydactyly when given intraperitoneally at doses of 750-1500 mg/kg. The teratogenic effects and dose relationships in these rats were similar for acetohydroxamic acid and hydroxyurea; the fetuses were more sensitive to the lethal effects of the drugs than were the mothers. Since the risks clearly outweigh any possible benefits in women who are or may become pregnant, acetohydroxamic acid is contraindicated in such women. Women of childbearing age should be instructed to use an effective form of contraception during acetohydroxamic acid therapy and informed of the potential hazard to the fetus should they become pregnant during therapy with the drug. If the drug is inadvertently administered during pregnancy or if the patient becomes pregnant while receiving the drug, the potential hazard to the fetus should be considered.

It is not known if acetohydroxamic acid is distributed into milk. Because of the potential for serious adverse reactions to acetohydroxamic acid in nursing infants, a decision should be made whether to discontinue nursing or to not use the drug, taking into account the importance of the drug to the woman.

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