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Drug Interactions between nelfinavir and Viekira XR

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

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Interactions between your drugs

Moderate

ritonavir nelfinavir

Applies to: Viekira XR (dasabuvir / ombitasvir / paritaprevir / ritonavir) and nelfinavir

ADJUST DOSE: Coadministration with ritonavir may significantly increase the plasma concentrations of nelfinavir. The mechanism is ritonavir inhibition of CYP450 3A4 metabolism of nelfinavir. According to the nelfinavir product labeling, ritonavir (500 mg orally every 12 hours for 3 doses) increased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of nelfinavir (750 mg single dose) by 44% and 152%, respectively, in 10 subjects (HIV status not stated). In a study involving 18 healthy volunteers, simultaneous administration of ritonavir (400 mg single oral dose) decreased the clearance of nelfinavir (750 mg single dose) 2-fold compared to when nelfinavir was administered alone. Nelfinavir had negligible effect on the pharmacokinetics of ritonavir.

MANAGEMENT: Alteration in dosages or regimen is recommended by the manufacturer of nelfinavir during concomitant therapy with ritonavir. However, appropriate dosages for the combination, with respect to safety and efficacy, have not been established. Patients receiving the combination should be closely monitored for toxicity such as elevations in liver function tests and undue gastrointestinal disturbances, and the dosage(s) adjusted as necessary.

References (4)
  1. (2001) "Product Information. Viracept (nelfinavir)." Agouron Pharma Inc
  2. Kempf DJ, Marsh KC, Kumar G, et al. (1997) "Pharmacokinetic enhancement of inhibitors of the human immunodeficiency virus protease by coadministration with ritonavir." Antimicrob Agents Chemother, 41, p. 654-60
  3. Kempf D, Marsh K, Denissen J, Kumar G, Rodrigues D, McDonald E, Flentge C, Green B, Chen X, Leonard J, Norbeck D (1996) "Coadministration with ritonavir enhances the plasma levels of HIV protease inhibitors by inhibition of cytochrome P450." 3rd Conf Retro and Opportun Infect, p. 79
  4. Lu JF, Blaschke TF, Flexner C, Rosenkranz SL, Sheiner LB (2002) "Model-based Analysis of the Pharmacokinetic Interactions Between Ritonavir, Nelfinavir, and Saquinavir after Simultaneous and Staggered Oral Administration." Drug Metab Dispos, 30, p. 1455-61
Moderate

nelfinavir paritaprevir

Applies to: nelfinavir and Viekira XR (dasabuvir / ombitasvir / paritaprevir / ritonavir)

MONITOR: Coadministration with potent inhibitors of CYP450 3A4 may increase the plasma concentrations of paritaprevir, which is primarily metabolized by the isoenzyme. In 12 study subjects, ketoconazole 400 mg given once daily increased single-dose paritaprevir peak plasma concentration (Cmax) and systemic exposure (AUC) by approximately 37% and 98%, respectively. The risk of hyperbilirubinemia may be increased, as paritaprevir can cause elevations in indirect (unconjugated) bilirubin via inhibition of OATP1B1/1B3.

MANAGEMENT: Caution is advised if paritaprevir is prescribed in combination with potent CYP450 3A4 inhibitors. Patients should be monitored for signs and symptoms of hepatotoxicity (i.e., ALT and bilirubin elevations).

References (1)
  1. (2022) "Product Information. Viekira Pak (dasabuvir/ombitasvir/paritaprev/ritonav)." AbbVie US LLC

Drug and food interactions

Moderate

ritonavir food

Applies to: Viekira XR (dasabuvir / ombitasvir / paritaprevir / ritonavir)

ADJUST DOSING INTERVAL: Administration with food may modestly affect the bioavailability of ritonavir from the various available formulations. When the oral solution was given under nonfasting conditions, peak ritonavir concentrations decreased 23% and the extent of absorption decreased 7% relative to fasting conditions. Dilution of the oral solution (within one hour of dosing) with 240 mL of chocolate milk or a nutritional supplement (Advera or Ensure) did not significantly affect the extent and rate of ritonavir absorption. When a single 100 mg dose of the tablet was administered with a high-fat meal (907 kcal; 52% fat, 15% protein, 33% carbohydrates), approximately 20% decreases in mean peak concentration (Cmax) and systemic exposure (AUC) were observed relative to administration after fasting. Similar decreases in Cmax and AUC were reported when the tablet was administered with a moderate-fat meal. In contrast, the extent of absorption of ritonavir from the soft gelatin capsule formulation was 13% higher when administered with a meal (615 KCal; 14.5% fat, 9% protein, and 76% carbohydrate) relative to fasting.

MANAGEMENT: Ritonavir should be taken with meals to enhance gastrointestinal tolerability.

References (1)
  1. (2001) "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical
Moderate

paritaprevir food

Applies to: Viekira XR (dasabuvir / ombitasvir / paritaprevir / ritonavir)

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of ombitasvir, paritaprevir, ritonavir, and dasabuvir. Relative to fasting conditions, administration of ombitasvir, paritaprevir, ritonavir, and dasabuvir with a moderate-fat meal (approximately 600 Kcal; 20% to 30% calories from fat) increased the mean systemic exposure (AUC) by 82%, 211%, 49%, and 30%, respectively. Relative to fasting conditions, administration of ombitasvir, paritaprevir, ritonavir, and dasabuvir with a high-fat meal (approximately 900 Kcal; with 60% calories from fat) increased the mean AUC by 76%, 180%, 44%, and 22%, respectively.

MANAGEMENT: Ombitasvir/paritaprevir/ritonavir plus dasabuvir should always be administered with a meal. The fat or calorie content does not matter.

References (1)
  1. (2022) "Product Information. Viekira Pak (dasabuvir/ombitasvir/paritaprev/ritonav)." AbbVie US LLC

Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Protease inhibitors

Therapeutic duplication

The recommended maximum number of medicines in the 'protease inhibitors' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'protease inhibitors' category:

  • nelfinavir
  • Viekira XR (dasabuvir/ombitasvir/paritaprevir/ritonavir)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

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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