Skip to main content

Drug Interactions between Estro-LA and indinavir

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

Edit list (add/remove drugs)

Interactions between your drugs

Minor

estradiol indinavir

Applies to: Estro-LA (estradiol) and indinavir

Coadministration with indinavir may increase the plasma concentrations of estrogens and progestins. The proposed mechanism is indinavir inhibition of CYP450 3A4, the isoenzyme involved in the metabolism of estrogens, some (if not all) progestins, and other steroids. According to product labeling, indinavir (800 mg every 8 hours) increased the area under the plasma concentration-time curve (AUC) of ethinyl estradiol and norethindrone (administered as Ortho-Novum 1/35 once daily) by approximately 25% each after one week. The clinical significance of these alterations is unknown but should be considered when selecting oral contraceptive and hormone replacement doses.

References

  1. "Product Information. Crixivan (indinavir)." Merck & Co., Inc PROD (2001):

Switch to consumer interaction data

Drug and food interactions

Moderate

indinavir food

Applies to: indinavir

ADJUST DOSING INTERVAL: According to the manufacturer, coadministration with a meal high in calories, fat, and protein reduces the absorption of indinavir. In ten patients given indinavir in this manner, the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of indinavir decreased by an average of 84% and 77%, respectively. In contrast, grapefruit juice may have only minor effects on the oral bioavailability of indinavir. The manufacturer's package labeling states that administration of a single 400 mg dose of indinavir with 8 oz. of grapefruit juice decreased indinavir AUC by an average of 26%. Likewise, a study consisting of 14 HIV-infected subjects found no uniform nor significant changes in steady-state indinavir AUC during administration with double-strength grapefruit juice compared to water. There was, however, a delay in absorption (Tmax) due to grapefruit juice that is unlikely to be of clinical significance.

MANAGEMENT: To ensure maximal oral absorption, indinavir should be administered without food but with water 1 hour before or 2 hours after a meal. Alternatively, indinavir may be administered with other liquids such as skim milk, juice, coffee, or tea, or with a light meal (e.g., dry toast with jelly, juice, and coffee with skim milk and sugar; corn flakes, skim milk and sugar).

References

  1. "Product Information. Crixivan (indinavir)." Merck & Co., Inc PROD (2001):
  2. Yeh KC, Deutsch PJ, Haddix H, Hesney M, Hoagland V, Ju WD, Justice SJ, Osborne B, Sterrett AT, Stone JA, Woolf E, Waldman S "Single-dose pharmacokinetics of indinavir and the effect of food." Antimicrob Agents Chemother 42 (1998): 332-8
  3. Shelton MJ, Wynn HE, Newitt RG, DiFrancesco R "Effects of grapefruit juice on pharmacokinetic exposure to indinavir in HIV-positive subjects." J Clin Pharmacol 41 (2001): 435-42

Switch to consumer interaction data

Minor

estradiol food

Applies to: Estro-LA (estradiol)

Coadministration with grapefruit juice may increase the bioavailability of oral estrogens. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. In a small, randomized, crossover study, the administration of ethinyl estradiol with grapefruit juice (compared to herbal tea) increased peak plasma drug concentration (Cmax) by 37% and area under the concentration-time curve (AUC) by 28%. Based on these findings, grapefruit juice is unlikely to affect the overall safety profile of ethinyl estradiol. However, as with other drug interactions involving grapefruit juice, the pharmacokinetic alterations are subject to a high degree of interpatient variability. Also, the effect on other estrogens has not been studied.

References

  1. Weber A, Jager R, Borner A, et al. "Can grapefruit juice influence ethinyl estradiol bioavailability?" Contraception 53 (1996): 41-7
  2. Schubert W, Eriksson U, Edgar B, Cullberg G, Hedner T "Flavonoids in grapefruit juice inhibit the in vitro hepatic metabolism of 17B-estradiol." Eur J Drug Metab Pharmacokinet 20 (1995): 219-24

Switch to consumer interaction data

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

Report options

Loading...
QR code containing a link to this page

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.

Medical Disclaimer