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Drug Interactions between guaifenesin / oxtriphylline and pentoxifylline

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

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Interactions between your drugs

Moderate

pentoxifylline oxtriphylline

Applies to: pentoxifylline and guaifenesin / oxtriphylline

MONITOR: Coadministration with pentoxifylline may increase the serum concentrations of theophylline. The mechanism of interaction has not been described, but may involve competitive metabolism as both drugs are methylxanthine derivatives. In nine healthy volunteers, mean serum theophylline trough concentration increased by 30% when theophylline (300 mg SR twice a day) was coadministered with pentoxifylline (400 mg three times a day) for 7 days. Studies indicate no interference with theophylline assays by pentoxifylline and its metabolites, although unusually high pentoxifylline serum concentrations have been reported when an enzyme-multiplied immunoassay (EMIT) is used.

MANAGEMENT: Caution is advised if theophylline preparations are used in combination with pentoxifylline. Serum theophylline concentrations should be monitored more closely following the initiation, discontinuation or change of dosage of pentoxifylline, and the theophylline dosage adjusted as necessary.

References (4)
  1. Cummings DM, Rocci ML Jr, Green P, Saccar C (1985) "Interference potential of pentoxifylline and its major metabolite with theophylline assays." Am J Hosp Pharm, 42, p. 2717-8
  2. Cohen IA, Johnson CE, Wesolowicz L, Converse-Swastek K (1988) "Effect of pentoxifylline and its metabolites on three theophylline assays." Clin Pharm, 7, p. 457-61
  3. Ellison MJ, Horner RD, Willis SE, Cummings DM (1990) "Influence of pentoxifylline on steady-state theophylline serum concentrations from sustained-release formulations." Pharmacotherapy, 10, p. 383-6
  4. (2001) "Product Information. Trental (pentoxifylline)." Hoechst Marion Roussel

Drug and food interactions

No alcohol/food interactions were found. However, this does not necessarily mean no interactions exist. Always consult your healthcare provider.

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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