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Drug Interactions between trimethoprim and zidovudine

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Minor

zidovudine trimethoprim

Applies to: zidovudine and trimethoprim

Limited data indicate that zidovudine may significantly increase the serum half-life of both trimethoprim (TMP) and sulfamethoxazole (SMX). The mechanism is not known, but may be related to an increase in the volume of distribution of each drug. In addition, trimethoprim can decrease the renal clearance of zidovudine and its glucuronide metabolite by inhibiting their tubular secretion. However, net clearance is not affected because zidovudine is mostly metabolized and the glucuronide may be eliminated via biliary excretion. This interaction is not likely to be clinically important except when hepatic glucuronidation is also impaired by liver disease or drug inhibition.
Recommended management consists of monitoring for side effects of each drug and reducing dosages as necessary.

References (3)
  1. Chatton JY, Munafo A, Chave JP, et al. (1992) "Trimethoprim, alone or in combination with sulphamethoxazole, decreases the renal excretion of zidovudine and its glucuronide." Br J Clin Pharmacol, 34, p. 551-4
  2. Canas E, Pachon J, Garciapesquera F, Castillo JR, Viciana P, Cisneros JM, Jimenezmejias ME (1996) "Absence of effect of trimethoprim-sulfamethoxazole on pharmacokinetics of zidovudine in patients infected with human immunodeficiency virus." Antimicrob Agents Chemother, 40, p. 230-3
  3. Lee BL, Safrin S, Makrides V, Gambertoglio JG (1996) "Zidovudine, trimethoprim, and dapsone pharmacokinetic interactions in patients with human immunodeficiency virus infection." Antimicrob Agents Chemother, 40, p. 1231-6

Drug and food interactions

Minor

zidovudine food

Applies to: zidovudine

Food may have variable effects on the oral bioavailability of zidovudine. Fatty foods have been reported to decrease the rate and extent of zidovudine absorption following oral administration. In a study of 13 AIDS patients, mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of zidovudine were 2.8 and 1.4 times higher, respectively, in fasting patients than in those administered the medication with breakfast. In addition, variations in plasma zidovudine concentrations were increased when administered in the fed state. In another study of eight patients, the time to reach peak concentration (Tmax) was increased from 0.68 to 1.95 hours, and Cmax was reduced by 50% when zidovudine was administered with a liquid high-fat meal relative to fasting. Protein meals can also delay the absorption and reduce the Cmax of zidovudine, although the extent of absorption is not significantly affected. The clinical significance of these alterations, if any, is unknown. The product labeling states that zidovudine may be taken with or without food.

References (4)
  1. Lotterer E, Ruhnke M, Trautman M, et al. (1991) "Decreased and variable systemic availability of zidovudine in patients with AIDS if administered with a meal." Eur J Clin Pharmacol, 40, p. 305-8
  2. Unadkat JD, Collier AC, Crosby SS, et al. (1990) "Pharmacokinetics of oral zidovudine (azidothymidine) in patients with AIDS when administered with and without a high-fat meal." AIDS, 4, p. 229-32
  3. (2001) "Product Information. Retrovir (zidovudine)." Glaxo Wellcome
  4. Sahai J, Gallicano K, Garber G, et al. (1992) "The effect of a protein meal on zidovudine pharmacokinetics in HIV-infected patients." Br J Clin Pharmacol, 33, p. 657-60

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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