The sulfonamides should not be used for the treatment of group A beta-hemolytic streptococcal infections. In an established infection, they will not eradicate the streptococcus, and therefore will not prevent sequelae such as rheumatic fever and glomerulonephritis.

Deaths associated with the administration of sulfonamides have been reported from hypersensitivity reactions, hepatocellular necrosis, agranulocytosis, aplastic anemia and other blood dyscrasias.

The presence of clinical signs such as sore throat, fever, arthralgia, cough, shortness of breath, pallor, purpura or jaundice may be early indications of serious reactions, including serious blood disorders.

General

Sulfonamides should be given with caution to patients with impaired renal or hepatic function and to those with severe allergy or bronchial asthma. In glucose-6-phosphate dehydrogenase-deficient individuals, hemolysis may occur. This reaction is frequently dose-related.

Information for Patients

See PATIENT INFORMATION section.

Laboratory Tests

Complete blood counts should be done frequently in patients receiving sulfonamides. If a significant reduction in the count of any formed blood element is noted, Gantanol should be discontinued. Urinalyses with careful microscopic examination and renal function tests should be performed during therapy, particularly for those patients with impaired renal function.

Drug Interactions

See DRUG INTERACTIONS section.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis: Sulfamethoxazole has not been adequately tested in animals to permit an evaluation of its carcinogenic potential.

Mutagenesis: Bacterial mutagenic studies have not been performed with sulfamethoxazole. No chromosomal damage was observed in human leukocytes cultured in vitro with sulfamethoxazole; the concentrations used exceeded blood levels of sulfamethoxazole following therapy with Gantanol.

Impairment of Fertility: No adverse effects on fertility or general reproductive performance were observed in rats given sulfamethoxazole in oral dosages as high as 350 mg/kg/day.

Pregnancy

Teratogenic Effects

Pregnancy Category C: In rats, oral doses of 533 mg/kg of sulfamethoxazole produced teratologic effects manifested mainly as cleft palates. The highest dose which did not cause cleft palates in rats was 512 mg/kg of sulfamethoxazole. In rabbits, 150 to 350 mg/kg/day increased maternal mortality but had no deleterious effects on fetal development.

There are no adequate and well-controlled studies of Gantanol in pregnant women. Gantanol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nonteratogenic Effects

See CONTRAINDICATIONS.

Nursing Mothers

See CONTRAINDICATIONS.

Pediatric Use

Gantanol is not recommended in pediatric patients under 2 months of age, except in the treatment of congenital toxoplasmosis as adjunctive therapy with pyrimethamine (see CONTRAINDICATIONS). At the present time there are insufficient clinical data on prolonged or recurrent therapy in chronic renal diseases of pediatric patients under 6 years of age.

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