Sulfamethoxizole
Sulfamethoxizole - General Information
A bacteriostatic antibacterial agent that interferes with folic acid synthesis in susceptible bacteria. Its broad spectrum of activity has been limited by the development of resistance. (From Martindale, The Extra Pharmacopoeia, 30th ed, p208)
Pharmacology of Sulfamethoxizole
Sulfamethoxizole is a sulfonamide drug that inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA). Sulfamethoxizole is normally given in combination with Trimethoprim (a dihydrofolate reductase inhibitor). Studies have shown that bacterial resistance develops more slowly with the combination of the two drugs than with either Trimethoprim or Sulfamethoxizole alone.
Sulfamethoxizole for patients
Patients should be instructed to maintain an adequate fluid intake in order to prevent crystalluria and stone formation.
Sulfamethoxizole Interactions
In elderly patients concurrently receiving certain diuretics, primarily thiazides, an increased incidence of thrombopenia with purpura has been reported.
It has been reported that sulfamethoxazole may prolong the prothrombin time in patients who are receiving the anticoagulant warfarin. This interaction should be kept in mind when Gantanol is given to patients already on anticoagulant therapy, and the coagulation time should be reassessed.
Sulfamethoxazole may inhibit the hepatic metabolism of phenytoin. At a 1.6-g dose, sulfamethoxazole produced a slight but significant increase in the half-life of phenytoin but did not produce a corresponding decrease in the metabolic clearance rate. When administering these drugs concurrently, one should be alert for possible excessive phenytoin effect.
Sulfonamides can also displace methotrexate from plasma protein-binding sites, thus increasing free methotrexate concentrations.
The presence of sulfamethoxazole may interfere with the Jaffé alkaline picrate reaction assay for creatinine, resulting in overestimations of about 10% in the range of normal values.
Sulfamethoxizole Contraindications
Hypersensitivity to sulfonamides. Pediatric patients less than 2 months of age (except in the treatment of congenital toxoplasmosis as adjunctive therapy with pyrimethamine). Pregnancy at term and during the nursing period because sulfonamides pass the placenta and are excreted in the milk and may cause kernicterus.
Additional information about Sulfamethoxizole
Sulfamethoxizole Indication: For the treatment of bronchitis, prostatitis and urinary tract infections.
Mechanism Of Action: Sulfonamides inhibit bacterial dihydrofolate synthetase, causing interference in the conversion of p-aminobenzoic acid (PABA) into folic acid. As folic acid is a coenzyme responsible for the transport of one-carbon fragments from one molecule to another, it is an essential component of bacterial development. Pyrimethamine and trimethoprim inhibit dihydrofolate reductase, the immediate next step, and therefore act synergistically with the sulfonamides.
Drug Interactions: Not Available
Food Interactions: Take on empty stomach: 1 hour before or 2 hours after meals.
Take with a full glass of water.
Do not take calcium, aluminium, magnesium or iron supplements within 2 hours of taking this medication.
Generic Name: Sulfamethoxazole
Synonyms: Not Available
Drug Category: Anti-Infectives; Sulfonamides
Drug Type: Small Molecule; Approved
Other Brand Names containing Sulfamethoxazole: Apo-Sulfamethoxazole; Azo Gantanol; Azo-Gantanol; Bactrimel; Gamazole; Gantanol; Gantanol-DS; Metoxal; Radonil; SIM; Septran; Simsinomin; Sinomin; Sulfamethalazole; Sulfamethoxazol; Sulfamethoxizole; Sulfamethylisoxazole; Sulfisomezole; Sulpha-Methoxizole; Sulphamethalazole; Sulphamethoxazol; Sulphamethoxazole; Sulphamethoxazole BP 98; Sulphamethylisoxazole; Sulphisomezole; Trib; Urobak;
Absorption: Rapidly absorbed following oral administration.
Toxicity (Overdose): Not Available
Protein Binding: 70%
Biotransformation: Hepatic. The metabolism of sulfamethoxazole occurs predominately by N4-acetylation, although the glucuronide conjugate has been identified.
Half Life: 10 hours
Dosage Forms of Sulfamethoxizole: Tablet Oral
Chemical IUPAC Name: 4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide
Chemical Formula: C10H11N3O3S
Sulfamethoxazole on Wikipedia: https://en.wikipedia.org/wiki/Sulfamethoxazole
Organisms Affected: Gram negative and gram positive bacteria
