Acetohydroxamic acid

Acetohydroxamic acid should not be used in patients who are pregnant.

It is not known whether AHA is secreted in human milk. Because many drugs are excreted in human milk, and because of the potential for serious adverse reactions in nursing infants from AHA, a decision should be made to discontinue nursing or the drug, taking into account the significance of the drug to the mother’s well being.

Well controlled, long-term animal studies that identify the carcinogenic potential of AHA treatment have not been conducted. Acetamide, a metabolite of AHA, has been shown to cause hepatocellular carcinoma in rats at oral doses 1,500 times the human dose. AHA is cytotoxic and was positive for mutagenicity in the Ames test.

Experience with AHA is limited. About 150 patients have been treated, most for periods of more than a year.

Adverse reactions have occurred in up to thirty percent (30%) of the patients receiving AHA. In some instances the reactions were symptomatic; in others only changes in laboratory parameters were noted. Adverse reactions seem to be more prevalent in patients with preexisting thrombophlebitis or phlebothrombosis and/or in patients with advanced degrees of renal insufficiency. The risk of adverse reactions is highest during the first year of treatment. Chronic treatment does not seem to increase the risk nor the severity of adverse reactions.

The following reactions have been reported:

NEUROLOGICAL: Mild headaches are commonly reported (about 30%) during the first 48 hours of treatment. These headaches are mild, responsive to oral salicylate-type analgesics, and usually disappear spontaneously. The headaches have not been associated with vertigo, tinnitus, or visual or auditory abnormalities. Tremulousness and nervousness have also been reported.

GASTROINTESTINAL: Gastrointestinal symptoms, nausea, vomiting, anorexia, and malaise have occurred in 20-25% of patients. In most patients the symptoms were mild, transitory, and did not result in interruption of treatment. Approximately 3% of patients developed a hemolytic anemia of sufficient magnitude to warrant interruption in treatment; several of these patients also had symptoms of gastrointestinal upset.

HEMATOLOGICAL: Approximately 15% of patients have had laboratory findings characteristic of a hemolytic anemia. A mild reticulocytosis (5- 6%) without anemia, is even more prevalent. The laboratory findings are occasionally accompanied by systemic symptoms such as malaise, lethargy and fatigue, and gastrointestinal symptoms. Symptoms and laboratory findings have invariably improved following cessation of treatment with AHA. The hematological abnormalities are more prevalent in patients with advanced renal failure.

DERMATOLOGICAL: A nonpruritic, macular skin rash has occurred in the upper extremities and on the face of several patients taking AHA on a long-term basis, usually when AHA has been taken concomitantly with alcoholic beverages, but in a few patients in the absence of alcohol consumption. The rash commonly appears 30-45 minutes after ingestion of alcoholic beverages; it characteristically disappears spontaneously in 30-60 minutes. The rash may be associated with a general sensation of warmth. In some patients the rash is sufficiently severe to warrant discontinuation of treatment, but most patients have continued treatment, avoiding alcohol or using smaller quantities of it. Alopecia has also been reported in patients taking AHA.

CARDIOVASCULAR: Superficial phlebitis involving the lower extremities has occurred in several patients on AHA during the early (Phase II) clinical trials. Several of the affected patients had had phlebitic episodes prior to treatment. One patient developed deep vein thrombosis of the lower extremities. The patient with phlebothrombosis had an associated traumatic injury to the groin. It is unclear whether the phlebitis was related to or exacerbated by treatment with AHA. No patient in the three (3) year controlled (Phase III) clinical trial developed phlebitis. In all instances these vascular abnormalities returned to normal following appropriate medical therapy. Embolic phenomena have been reported in three patients taking AHA in the Phase II trial. The phlebitis and emboli resolved following discontinuation of AHA and implementation of appropriate medical therapy. Several patients have resumed treatment with AHA without ill effect. Palpitations have also been reported in patients taking AHA.

RESPIRATORY: No symptoms have been reported. Radiographic evidence of small pulmonary emboli has been seen in three patients with phlebitis in their lower legs.

PSYCHIATRIC: Depression, anxiety, nervousness, and tremulousness have been observed in approximately 20% of patients taking AHA. In most patients the symptoms were mild and transitory, but in about 6% of patients the symptoms were sufficiently distressing to warrant interruption or discontinuation of treatment.