Drug General Information (ID: DDISW2G4MT)
Drug Name			Trimethoprim		Drug Info		Zalcitabine		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antiinfective Agents				Anti-Hiv Agents
Structure

Mechanism of Trimethoprim-Zalcitabine Interaction (Severity Level: Moderate)
Competitive inhibition of renal tubular secretion Click to Show/Hide Mechanism Graph
Drug Name		Trimethoprim				Zalcitabine
Mechanism		Inhibition of renal tubular secretion of zalcitabine				Zalcitabine
Key Mechanism Factor 1
		Factor Name		Renal tubular secretion
		Factor Description		Renal tubular secretion allows selective transfer of substances from the blood around the capillaries into the renal tubules via filtrate. Drug excretion may be reduced when two drugs compete for renal tubular secretion.
Mechanism Description		Decreased elimination of Zalcitabine caused by Trimethoprim mediated competitive inhibition of renal tubular secretion

Recommended Action
Management		Close clinical monitoring for evidence of zalcitabine toxicity (peripheral neuropathy, pancreatitis, lactic acidosis, hepatotoxicity) is recommended when these drugs are used together. In addition, a reduction in zalcitabine dosage may be warranted. Patients should be advised to promptly notify their doctor if they experience numbness, tingling, severe nausea and vomiting, diarrhea, abdominal pain, severe fatigue, or jaundice.

References
1	Cerner Multum, Inc. "UK Summary of Product Characteristics.".
2	Multum Information Services, Inc. Expert Review Panel.
3	Product Information. Hivid (zalcitabine). Roche Laboratories, Nutley, NJ.