MEZENOL 480 MG TABLET

Indications

• Urinary tract infections
• Respiratory tract infections
• Gastrointestinal infections
• Pneumocystis pneumonia
• Skin and soft tissue infections

Dosage

Children: Refer to specific pediatric dosage guidelines or resources.

Adults: Refer to specific guidelines or prescribing information for appropriate dosing.

Mechanism of action

Trimethoprim is a dihydrofolate reductase inhibitor, preventing the reduction of dihydrofolate to tetrahydrofolate, which is necessary for the synthesis of nucleic acids. Sulfamethoxazole, a sulfonamide, inhibits dihydropteroate synthase, blocking the conversion of para-aminobenzoic acid (PABA) to dihydropteroic acid, a precursor in folate synthesis. Together, they disrupt folate synthesis in bacteria, leading to inhibition of bacterial growth.

Pharmacodynamics

Trimoxazole exhibits bactericidal properties due to the synergistic action of its components. The inhibition of folate synthesis affects the production of nucleic acids and ultimately leads to cell death in susceptible bacteria. The drug's efficacy is influenced by the bacterial sensitivity to trimethoprim and sulfamethoxazole, as well as the concentration of the drug at the site of infection.

Pharmacokinetics

Trimoxazole is well absorbed after oral administration, with peak plasma concentrations occurring within 1 to 4 hours. It is distributed widely throughout body tissues and fluids, including the lungs, liver, and urine. The protein binding of trimethoprim is approximately 45% to 60%, while sulfamethoxazole binds to about 70% of plasma proteins. Both components are metabolized in the liver, with renal excretion being the primary route for elimination. The half-lives of trimethoprim and sulfamethoxazole are approximately 8 to 10 hours and 10 hours, respectively.

Contra-indications

• Hypersensitivity to trimethoprim or sulfonamides
• Severe hepatic impairment
• Severe renal impairment
• Blood dyscrasias

Adverse effects

• Nausea
• Vomiting
• Rash
• Fever
• Leukopenia
• Thrombocytopenia
• Hepatotoxicity
• Hyperkalaemia
• Allergic reactions

Interactions

• Increased effect of anticoagulants (e.g., warfarin)
• Increased risk of hyperkalemia with potassium-sparing diuretics
• Potential reduction in efficacy of oral contraceptives
• Increased levels of methotrexate

Precautions

• Monitor renal function during prolonged therapy
• Use caution in patients with history of drug allergies
• Consider risk of folate deficiency
• Careful monitoring in elderly patients

Pregnancy

Trimethoprim-sulfamethoxazole should be avoided during the first trimester and near term due to potential risks to the fetus.

Breast-feeding

Trimethoprim-sulfamethoxazole is excreted in breast milk; caution is advised when administering to nursing mothers.

Storage

Store in a cool, dry place away from direct light. Keep out of reach of children.

Formulations

• Oral tablet
• Oral suspension
• Injectable solution