Question

Cotrimoxazole is combination of sulfamethoxazole and trimethoprim in the ratio of

• A. 5:1
• B. 1:20
• C. 1:2
• D. 1:1

Hint:

Remember: SMZ (5) : TMP (1). The longer name (Sulfamethoxazole) has the larger number.

Answer 1

The Correct Option is A

Step 1: Concept
Cotrimoxazole is a fixed-dose combination antibiotic that exerts a synergistic effect by blocking two consecutive steps in bacterial folate synthesis.

Step 2: Meaning
The combination consists of Sulfamethoxazole (an intermediate-acting sulfonamide) and Trimethoprim.

Step 3: Analysis
For optimal synergistic activity in the body, the components are mixed in a specific weight ratio. The standard ratio is 5 parts Sulfamethoxazole to 1 part Trimethoprim (e.g., 400mg + 80mg).

Step 4: Conclusion
Therefore, the correct pharmaceutical ratio for Cotrimoxazole is 5:1.

Final Answer: (A)