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Drug Interactions between fosamprenavir and lansoprazole / naproxen

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

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Interactions between your drugs

Moderate

naproxen lansoprazole

Applies to: lansoprazole / naproxen and lansoprazole / naproxen

GENERALLY AVOID: Theoretically, proton pump inhibitors may decrease the gastrointestinal absorption of enteric-coated naproxen, which requires an acidic environment for dissolution. The proposed mechanism is an increase in gastric pH (i.e. decreased gastric acidity) induced by proton pump inhibitors. In patients treated with proton pump inhibitors, the possibility of a reduced or subtherapeutic response to enteric-coated naproxen should be considered.

MANAGEMENT: Concomitant use of these drugs is generally not recommended.

References (1)
  1. (2002) "Product Information. Naprosyn (naproxen)." Syntex Laboratories Inc
Moderate

lansoprazole fosamprenavir

Applies to: lansoprazole / naproxen and fosamprenavir

MONITOR: Coadministration with H2-receptor antagonists or inhibitors of the proton pump (PPIs or potassium-competitive acid blockers [PCABs]) may decrease the oral bioavailability of amprenavir from its prodrug, fosamprenavir. In 30 study subjects, ranitidine (300 mg single oral dose) decreased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of amprenavir from fosamprenavir (1400 mg single oral dose) by 51% and 30%, respectively, compared to administration of fosamprenavir alone. The mechanism of interaction has not been described. It is possible that fosamprenavir solubility decreases with increasing pH, thus inhibition of gastric acid secretion may interfere with dissolution of the drug. Subtherapeutic antiretroviral drug levels may lead to reduced viral susceptibility and development of resistance.

MANAGEMENT: Caution is advised if fosamprenavir is prescribed with H2-receptor antagonists or inhibitors of the proton pump. Antiretroviral response should be monitored closely during coadministration.

References (3)
  1. (2003) "Product Information. Lexiva (fosamprenavir)." GlaxoSmithKline
  2. (2022) "Product Information. Voquezna Dual Pak (amoxicillin-vonoprazan)." Phathom Pharmaceuticals, Inc
  3. (2022) "Product Information. Voquezna Triple Pak (amoxicillin/clarithromycin/vonoprazan)." Phathom Pharmaceuticals, Inc

Drug and food interactions

Moderate

fosamprenavir food

Applies to: fosamprenavir

ADJUST DOSING INTERVAL: Food may reduce the systemic bioavailability of amprenavir from fosamprenavir oral suspension. The mechanism of interaction has not been described. According to the product labeling, administration of fosamprenavir oral suspension (1400 mg single dose) with a high-fat meal (967 kcal, 67 g fat, 33 g protein, 58 g carbohydrate) reduced amprenavir peak plasma concentration (Cmax) by 46% and systemic exposure (AUC) by 28% compared to administration in a fasted state. The time to reach peak plasma level (Tmax) was delayed by 0.72 hours. In contrast, the same high-fat meal did not affect the pharmacokinetics of amprenavir from fosamprenavir tablets.

MANAGEMENT: Fosamprenavir suspension should be administered on an empty stomach in adults, but with food in pediatric patients to aid palatability and compliance. If emesis occurs within 30 minutes after dosing the suspension, the dose should be repeated. Fosamprenavir tablets may be taken with or without food.

References (1)
  1. (2003) "Product Information. Lexiva (fosamprenavir)." GlaxoSmithKline
Moderate

naproxen food

Applies to: lansoprazole / naproxen

GENERALLY AVOID: The concurrent use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) and ethanol may lead to gastrointestinal (GI) blood loss. The mechanism may be due to a combined local effect as well as inhibition of prostaglandins leading to decreased integrity of the GI lining.

MANAGEMENT: Patients should be counseled on this potential interaction and advised to refrain from alcohol consumption while taking aspirin or NSAIDs.

References (1)
  1. (2002) "Product Information. Motrin (ibuprofen)." Pharmacia and Upjohn
Moderate

naproxen food

Applies to: lansoprazole / naproxen

MONITOR: Smoking cessation may lead to elevated plasma concentrations and enhanced pharmacologic effects of drugs that are substrates of CYP450 1A2 (and possibly CYP450 1A1) and/or certain drugs with a narrow therapeutic index (e.g., flecainide, pentazocine). One proposed mechanism is related to the loss of CYP450 1A2 and 1A1 induction by polycyclic aromatic hydrocarbons in tobacco smoke; when smoking cessation agents are initiated and smoking stops, the metabolism of certain drugs may decrease leading to increased plasma concentrations. The mechanism by which smoking cessation affects narrow therapeutic index drugs that are not known substrates of CYP450 1A2 or 1A1 is unknown. The clinical significance of this interaction is unknown as clinical data are lacking.

MANAGEMENT: Until more information is available, caution is advisable if smoking cessation agents are used concomitantly with drugs that are substrates of CYP450 1A2 or 1A1 and/or those with a narrow therapeutic range. Patients receiving smoking cessation agents may require periodic dose adjustments and closer clinical and laboratory monitoring of medications that are substrates of CYP450 1A2 or 1A1.

References (4)
  1. (2024) "Product Information. Cytisine (cytisinicline)." Consilient Health Ltd
  2. jeong sh, Newcombe D, sheridan j, Tingle M (2015) "Pharmacokinetics of cytisine, an a4 b2 nicotinic receptor partial agonist, in healthy smokers following a single dose." Drug Test Anal, 7, p. 475-82
  3. Vaughan DP, Beckett AH, Robbie DS (1976) "The influence of smoking on the intersubject variation in pentazocine elimination." Br J Clin Pharmacol, 3, p. 279-83
  4. Zevin S, Benowitz NL (1999) "Drug interactions with tobacco smoking: an update" Clin Pharmacokinet, 36, p. 425-38

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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