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Drug Interactions between indinavir and Niferex-150

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

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Interactions between your drugs

Minor

ascorbic acid indinavir

Applies to: Niferex-150 (ascorbic acid/iron polysaccharide) and indinavir

Coadministration with high dosages of vitamin C (1 g/day or more) may decrease the plasma concentrations of indinavir. The exact mechanism of interaction is unknown, although preliminary data suggest that vitamin C may induce CYP450 3A4, the isoenzyme responsible for the metabolic clearance of indinavir. In seven healthy volunteers (six males and one female), pretreatment with vitamin C (1000 mg daily for 7 days) decreased the mean peak plasma concentration (Cmax) and systemic exposure (AUC) of indinavir (800 mg for 4 doses, 8 hours apart) by 20% and 14%, respectively, compared to administration of indinavir alone. Mean indinavir trough plasma concentration (Cmin) was 32% lower with vitamin C, but the difference was not statistically significant. There was no significant difference in indinavir oral clearance and elimination half-life. The clinical relevance of this interaction is uncertain. A study involving a larger number of patients (including more women), use of higher dosages of vitamin C, and concomitant administration of ritonavir would be helpful.

References

  1. Amsden JR, Hobbs GR, Fisher MA, Slain D, Khakoo RA, Lalka D (2003) Effect of high-dose vitamin C on the steady-state pharmacokinetics of the protease inhibitor indinavir in healthy volunteers. http://www.icaac.org/ICAAC.asp
  2. (2003) "Anti-HIV agents. High-dose vitamin C may affect indinavir users." TreatmentUpdate, 15, p. 5-6

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Drug and food interactions

Moderate

iron polysaccharide food

Applies to: Niferex-150 (ascorbic acid/iron polysaccharide)

ADJUST DOSING INTERVAL: Concomitant use of some oral medications may reduce the bioavailability of orally administered iron, and vice versa.

Food taken in conjunction with oral iron supplements may reduce the bioavailability of the iron. However, in many patients intolerable gastrointestinal side effects occur necessitating administration with food.

MANAGEMENT: Ideally, iron products should be taken on an empty stomach (i.e., at least 1 hour before or 2 hours after meals), but if this is not possible, administer with meals and monitor the patient more closely for a subtherapeutic effect. Some studies suggest administration of iron with ascorbic acid may enhance bioavailability. In addition, administration of oral iron products and some oral medications should be separated whenever the bioavailability of either agent may be decreased. Consult the product labeling for specific separation times and monitor clinical responses as appropriate.

References

  1. "Product Information. Feosol (ferrous sulfate)." SmithKline Beecham
  2. (2021) "Product Information. Accrufer (ferric maltol)." Shield Therapeutics

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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. (2001) "Product Information. Crixivan (indinavir)." Merck & Co., Inc
  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 (1998) "Single-dose pharmacokinetics of indinavir and the effect of food." Antimicrob Agents Chemother, 42, p. 332-8
  3. Shelton MJ, Wynn HE, Newitt RG, DiFrancesco R (2001) "Effects of grapefruit juice on pharmacokinetic exposure to indinavir in HIV-positive subjects." J Clin Pharmacol, 41, p. 435-42

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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

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