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Drug Interactions between Ilosone and Rapaflo

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

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Interactions between your drugs

Moderate

erythromycin silodosin

Applies to: Ilosone (erythromycin) and Rapaflo (silodosin)

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of silodosin, which is primarily metabolized by the isoenzyme. In a pharmacokinetic study, administration of a single 8 mg dose of silodosin with the potent CYP450 3A4 inhibitor ketoconazole (400 mg) resulted in a 3.8-fold increase in silodosin peak plasma concentration (Cmax) and a 3.2-fold increase in systemic exposure (AUC). The interaction has not been studied with moderate CYP450 3A4 inhibitors such as diltiazem, erythromycin, and verapamil.

MANAGEMENT: Caution is advised if silodosin is prescribed in combination with inhibitors of CYP450 3A4. Pharmacologic response to silodosin should be monitored more closely whenever a CYP450 3A4 inhibitor is added to or withdrawn from therapy, and the silodosin dosage adjusted as necessary. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia. Taking silodosin at bedtime may minimize the occurrence of orthostatic effects. Patients should also avoid driving or operating hazardous machinery until they know how the medication affects them.

References

  1. (2008) "Product Information. Rapaflo (silodosin)." Watson Pharmaceuticals

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Drug and food interactions

Moderate

erythromycin food

Applies to: Ilosone (erythromycin)

ADJUST DOSING INTERVAL: Food may variably affect the bioavailability of different oral formulations and salt forms of erythromycin. The individual product package labeling should be consulted regarding the appropriate time of administration in relation to food ingestion. Grapefruit juice may increase the plasma concentrations of orally administered erythromycin. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. In an open-label, crossover study consisting of six healthy subjects, the coadministration with double-strength grapefruit juice increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of a single dose of erythromycin (400 mg) by 52% and 49%, respectively, compared to water. The half-life was not affected. The clinical significance of this potential interaction is unknown.

MANAGEMENT: In general, optimal serum levels are achieved when erythromycin is taken in the fasting state, one-half to two hours before meals. However, some erythromycin products may be taken without regard to meals.

References

  1. Welling PG, Huang H, Hewitt PF, Lyons LL (1978) "Bioavailability of erythromycin stearate: influence of food and fluid volume." J Pharm Sci, 67, p. 764-6
  2. Welling PG, Elliott RL, Pitterle ME, et al. (1979) "Plasma levels following single and repeated doses of erythromycin estolate and erythromycin stearate." J Pharm Sci, 68, p. 150-5
  3. Welling PG (1977) "Influence of food and diet on gastrointestinal drug absorption: a review." J Pharmacokinet Biopharm, 5, p. 291-334
  4. Coyne TC, Shum S, Chun AH, Jeansonne L, Shirkey HC (1978) "Bioavailability of erythromycin ethylsuccinate in pediatric patients." J Clin Pharmacol, 18, p. 194-202
  5. Malmborg AS (1979) "Effect of food on absorption of erythromycin. A study of two derivatives, the stearate and the base." J Antimicrob Chemother, 5, p. 591-9
  6. Randinitis EJ, Sedman AJ, Welling PG, Kinkel AW (1989) "Effect of a high-fat meal on the bioavailability of a polymer-coated erythromycin particle tablet formulation." J Clin Pharmacol, 29, p. 79-84
  7. Kanazawa S, Ohkubo T, Sugawara K (2001) "The effects of grapefruit juice on the pharmacokinetics of erythromycin." Eur J Clin Pharmacol, 56, p. 799-803
View all 7 references

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Moderate

silodosin food

Applies to: Rapaflo (silodosin)

ADJUST DOSING INTERVAL: Food may reduce the oral bioavailability of silodosin. The effect of a moderate-fat, moderate-calorie meal on silodosin pharmacokinetics was variable and decreased silodosin maximum plasma concentration (Cmax) by approximately 18% to 43% and systemic exposure (AUC) by 4% to 49% across three different studies. The maximum effect of food (i.e., coadministration with a high-fat, high-calorie meal) on the pharmacokinetics of silodosin was not evaluated. Safety and efficacy clinical trials for silodosin were always conducted in the presence of food intake.

MANAGEMENT: Patients should be instructed to take silodosin with a meal to reduce the risk of adverse events.

References

  1. (2008) "Product Information. Rapaflo (silodosin)." Watson Pharmaceuticals

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Minor

erythromycin food

Applies to: Ilosone (erythromycin)

Ethanol, when combined with erythromycin, may delay absorption and therefore the clinical effects of the antibiotic. The mechanism appears to be due to slowed gastric emptying by ethanol. Data is available only for erythromycin ethylsuccinate. Patients should be advised to avoid ethanol while taking erythromycin salts.

References

  1. Morasso MI, Chavez J, Gai MN, Arancibia A (1990) "Influence of alcohol consumption on erythromycin ethylsuccinate kinetics." Int J Clin Pharmacol, 28, p. 426-9

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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.

See also

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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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