Drug General Information (ID: DDIYAEIL1B)
Drug Name			Trimethoprim		Drug Info		Leucovorin		Drug Info
Drug Type		Small molecule				Small molecule
Therapeutic Class		Antiinfective Agents				Folate Supplements
Structure

Mechanism of Trimethoprim-Leucovorin Interaction (Severity Level: Major)
Attenuated pharmacological effects (Unspecific) Click to Show/Hide Mechanism Graph
Drug Name		Trimethoprim				Leucovorin
Mechanism		Antifolate effects				Folate derivatives
Key Mechanism Factor 1
		Factor Name		Pharmacodynamics
		Factor Description		Reduced pharmacological effects leading to insufficient efficacy and/or treatment failure.
Mechanism Description		Attenuated pharmacological effects of  Trimethoprim when combined with Leucovorin

Recommended Action
Management		The use of leucovorin in immunosuppressed patients receiving SMX-TMP for treatment of Pneumocystis jiroveci pneumonia should be avoided unless benefits are anticipated to outweigh the risks.

References
1	Bozzette SA, Forthal D, Sattler FR, Kemper C, Richman DD, Tilles JG, Leedom J, Mccutchan JA "The tolerance for zidovudine plus thrice weekly or daily trimethoprim-sulfamethoxazole with and without leucovorin for primary prophylaxis in advanced HIV disease." Am J Med 98 (1995): 177-82. [PMID: 7847434]
2	Product Information. Levoleucovorin (levoleucovorin). Spectrum Chemical, Gardena, CA.
3	Razavi B, Lund B, Allen BL, Schlesinger L "Failure of trimethoprim/sulfamethoxazole prophylaxis for Pneumocystis carinii pneumonia with concurrent leucovorin use." Infection 30 (2002): 41-2. [PMID: 11876516]