Sulfamethoxazole/ Trimethoprim (Co-trimoxazole)

Tablets:

• 120mg (sulfamethoxazole 100mg + trimethoprim 20mg)
• 480mg (sulfamethoxazole 400mg + trimethoprim 80mg)
• 960mg (sulfamethoxazole 800mg + trimethoprim 160mg)

Suspension:

• Each 5ml has 240mg (sulfamethoxazole 200mg + trimethoprim 40mg)

• May be given with or without food.
• Dapsone may be used in place of cotrimoxazole when necessary.

Trimethoprim: Reversibly inhibits dihydrofolate reductase(DHFR), thereby blocking production of tetrahydrofolic acid from dihydrofolic acid.

Sulfamethoxazole: Inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA).

Therefore, they block two consecutive steps in the biosynthesis of nucleic acids and proteins essential to many bacteria.

• GI disturbances and skin reactions.
• Occasional deaths especially in elderly patients due to blood dyscrasias or severe skin infections.
• Nausea and vomiting
• Kernicterus in newborn infants or nursing child if mother is using the drug.
• Erythema
• Toxic epidermal necrolysis
• Allergic vasculitis
• Glossitis
• Stomatitis
• Transient jaundice
• Acidosis
• Goitre
• Tinnitus and peripheral neuritis in high doses.

• Renal and hepatic failure.
• Children < 6 weeks old.
• Hypersensitivity to sulfonamides or trimethoprim.
• G6PD deficient individuals
• Megaloblastic anemia due to folate deficiency
• Acute porphyria
• Premature/newborn infants
• Pregnancy & lactation
• Concurrent use with anticonvulsant medication

CAUTION:

• Regular blood count should be done with prolonged use.
• Severe allergy or bronchial asthma.
• Renal impairment
• Elderly

• Clozapine
• Sulfadoxine/pyrimethamine, alone or in combination with artesunate
• Amodiaquine
• Sulfonyureas (increases hypoglycemic action)
• Prolongs half life of phenytoin and rifampicin.
• Diuretics increase risk of thrombocytopenia
• Methotrexate
• Phenytoin
• Zidovudine
• Ganciclovir
• Dapsone
• Warfarin