Omeprazole with Nelfinavir Interaction Details

Brand Names Associated with Omeprazole

Brand Names Associated with Nelfinavir

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 05, 2023

Interaction Effect

Reduced nelfinavir exposure and reduced efficacy of nelfinavir

Interaction Summary

Coadministration of nelfinavir and omeprazole is not recommended due to the risk of substantially decreased nelfinavir plasma concentrations. Decreased nelfinavir plasma concentrations may result in loss of therapeutic effect and the development of resistance. Coadministration of nelfinavir and omeprazole significantly reduced the systemic exposure of nelfinavir and its active metabolite, M8 in an open-label, two-period, single-fixed sequence study in 20 subjects . In a retrospective cohort study of adult HIV-positive patients who received at least 2 prescriptions for nelfinavir, an intent-to-treat-like analysis revealed increased risk for virologic rebound in patients with concomitant PPI exposure, particularly long-term exposure, compared with those who were not exposed; however, an as-treated analysis found no significant difference in virologic rebound between the 2 groups .

Severity

Major

Onset

Unspecified

Evidence

Established

How To Manage Interaction

The concomitant use of nelfinavir and omeprazole is not recommended as concurrent use may result in reduced nelfinavir plasma concentrations, loss of nelfinavir efficacy, and development of resistance.

Mechanism Of Interaction

Unknown

Literature Reports

A) Coadministration of nelfinavir and omeprazole appeared to significantly reduce the systemic exposure of nelfinavir and its active metabolite, M8. In an open-label, two-period, single-fixed sequence study, 20 subjects (ages 18 to 48 years) received nelfinavir 1250 mg every 12 hours days 1 through 3 and 1250 mg the morning of day 4 (period 1). Following a 7 day washout, subjects received omeprazole 40 mg every 24 hours and nelfinavir 1250 mg every 12 hours for 3 days and omeprazole 40 mg with nelfinavir 1250 mg the morning of day 4 (period 2). Plasma samples showed decreases of 36%, 37%, and 39% in nelfinavir Cmax, AUC, and Cmin, respectively, compared to nelfinavir alone. In addition, the M8 metabolite was measured and showed a reduction of 92% (Cmax), 89% (AUC), and 75% (Cmin) .

B) In a retrospective cohort study of adult HIV-positive patients who received at least 2 prescriptions for nelfinavir, an intent-to-treat (ITT)-like analysis revealed increased risk for virologic rebound in patients with concomitant proton-pump inhibitor (PPI) exposure, particularly long-term exposure, compared with those who were not exposed; however, an as-treated analysis found no significant difference in virologic rebound between the 2 groups. The primary endpoints were time to virologic undetectability (HIV viral load less than 75 copies/mL) and time to virologic rebound (HIV viral load 75 copies/mL or more after previous virologic undetectability). Patients were followed until nelfinavir discontinuation, an insurance lapse of 3 or more months, a delay of more than 30 days in nelfinavir refill, achievement of primary endpoint, or end of study. The ITT-like analysis assumed continuous use of PPI once prescribed whereas in the as-treated analysis, patients were considered to be exposed to the PPI only until 30 days after the last PPI refill was expected to run out. There was no significant difference in the time to virologic undetectability in either analysis. However, the ITT-like adjusted results showed a significantly increased risk for virologic rebound in nelfinavir-treated patients with PPI exposure compared with those with no PPI exposure (hazard ratio (HR), 1.53; 95% confidence interval (CI), 1.06 to 2.19; p=0.02). Stratifying data by length of PPI exposure revealed a 56% increased risk of virologic rebound (HR, 1.56; 95% CI, 1.08 to 2.26; p=0.02) with long-term exposure (30 days or greater) but not with short-term exposure (less than 30 days); however, this increased risk was not significant in the as-treated analysis .

Omeprazole Overview

• Prescription omeprazole is used alone or with other medications to treat the symptoms of gastroesophageal reflux disease (GERD), a condition in which backward flow of acid from the stomach causes heartburn and possible injury of the esophagus (the tube between the throat and stomach) in adults and children 1 year of age and older. Prescription omeprazole is used to treat damage from GERD in adults and children 1 month of age and older. Prescription omeprazole is used to allow the esophagus to heal and prevent further damage to the esophagus in adults and children 1 year of age and older with GERD. Prescription omeprazole is also used to treat conditions in which the stomach produces too much acid such as Zollinger-Ellison syndrome in adults. Prescription omeprazole is also used to treat ulcers (sores in the lining of the stomach or intestine) and it is also used with other medications to treat and prevent the return of ulcers caused by a certain type of bacteria (H. pylori) in adults. Nonprescription (over-the-counter) omeprazole is used to treat frequent heartburn (heartburn that occurs at least 2 or more days a week) in adults. Omeprazole is in a class of medications called proton-pump inhibitors. It works by decreasing the amount of acid made in the stomach.

Nelfinavir Overview

• Nelfinavir is used along with other medications to treat human immunodeficiency virus (HIV) infection. Nelfinavir is in a class of medications called protease inhibitors. It works by decreasing the amount of HIV in the blood. Although nelfinavir does not cure HIV, it may decrease your chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer. Taking these medications along with practicing safer sex and making other lifestyle changes may decrease the risk of transmitting the HIV virus to other people.

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Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.

Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.

Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.

Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.

Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.

Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.

How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.

Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.

Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.