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Drug Interactions between aminophylline / guaifenesin and pentoxifylline

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

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Interactions between your drugs

Moderate

pentoxifylline aminophylline

Applies to: pentoxifylline and aminophylline / guaifenesin

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

  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
View all 4 references

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Drug and food interactions

Moderate

aminophylline food

Applies to: aminophylline / guaifenesin

MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.

References

  1. Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr (1979) "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res, 1, p. 45-52
  2. Cavanaugh JH, Griffith JD, Oates JA (1970) "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther, 11, p. 656
  3. (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
  4. (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
  5. (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
  6. (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
  7. (2002) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
View all 7 references

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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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