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Drug Interactions between Alka-Seltzer Lemon-Lime and amprenavir

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

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Interactions between your drugs

Moderate

aspirin sodium bicarbonate

Applies to: Alka-Seltzer Lemon-Lime (aspirin/citric acid/sodium bicarbonate) and Alka-Seltzer Lemon-Lime (aspirin/citric acid/sodium bicarbonate)

MONITOR: Agents that cause urinary alkalinization can reduce serum salicylate concentrations in patients receiving anti-inflammatory dosages of aspirin or other salicylates. The mechanism involves reduction in salicylate renal tubular reabsorption due to increased urinary pH, resulting in increased renal salicylate clearance especially above urine pH of 7. This interaction is sometimes exploited in the treatment of salicylate toxicity.

MANAGEMENT: Patients treated chronically with urinary alkalinizers and large doses of salicylates (i.e. 3 g/day or more) should be monitored for potentially diminished or inadequate analgesic and anti-inflammatory effects, and the salicylate dosage adjusted if necessary.

References (5)
  1. Berg KJ (1977) "Acute acetylsalicylic acid poisoning: treatment with forced alkaline diuresis and diuretics." Eur J Clin Pharmacol, 12, p. 111-6
  2. Prescott LF, Balali-Mood M, Critchley JA, Johnstone AF, Proudfoot AT (1982) "Diuresis or urinary alkalinisation for salicylate poisoning?" Br Med J (Clin Res Ed), 285, p. 1383-6
  3. Balali-Mood M, Prescott LF (1980) "Failure of alkaline diuresis to enhance diflunisal elimination." Br J Clin Pharmacol, 10, p. 163-5
  4. Berg KJ (1977) "Acute effects of acetylsalicylic acid in patients with chronic renal insufficiency." Eur J Clin Pharmacol, 11, p. 111-6
  5. Brouwers JRBJ, Desmet PAGM (1994) "Pharmacokinetic-pharmacodynamic drug interactions with nonsteroidal anti-inflammatory drugs." Clin Pharmacokinet, 27, p. 462-85
Moderate

sodium bicarbonate amprenavir

Applies to: Alka-Seltzer Lemon-Lime (aspirin/citric acid/sodium bicarbonate) and amprenavir

ADJUST DOSING INTERVAL: Concurrent administration of antacids or other agents with acid-neutralizing effects may decrease the oral bioavailability of amprenavir and reduce its concentrations in plasma. Amprenavir solubility decreases with increasing pH, thus reduction in gastric acidity may interfere with dissolution of the drug. Subtherapeutic antiretroviral drug levels may lead to reduced viral susceptibility and development of resistance. In contrast, the prodrug fosamprenavir appears to be less affected by antacids. Administration of a single 1400 mg dose with 30 mL of antacid (Maalox TC) resulted in decreased peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of amprenavir by 35% and 18%, respectively. However, trough plasma concentration (Cmin) increased by 14%.

MANAGEMENT: Amprenavir should be administered at least 1 hour before or after antacids or other oral preparations containing antacids (e.g., didanosine buffered tablets or pediatric oral solution).

References (2)
  1. (2001) "Product Information. Agenerase (amprenavir)." Glaxo Wellcome
  2. (2003) "Product Information. Lexiva (fosamprenavir)." GlaxoSmithKline

Drug and food interactions

Moderate

amprenavir food

Applies to: amprenavir

GENERALLY AVOID: Administration with a high-fat meal may decrease the oral bioavailability of amprenavir. The mechanism is unknown. In healthy volunteers, consumption of a standardized high-fat meal decreased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of amprenavir (1200 mg single oral dose) by 36% and 21%, respectively, compared to administration in the fasted state. The time to reach Cmax (Tmax) was increased 44% following a high-fat meal.

Grapefruit juice does not appear to significantly affect the pharmacokinetics of amprenavir. In 12 healthy volunteers, administration with grapefruit juice (200 mL) decreased the mean peak plasma concentration (Cmax) of amprenavir (1200 mg single oral dose) by 22% compared to water. The median time to reach Cmax (Tmax) was prolonged from 0.75 to 1.13 hours. These pharmacokinetic changes are not thought to be clinically significant, since antiretroviral response is more closely associated with systemic exposure (AUC) and trough plasma concentration (Cmin), which were not affected in the study.

MANAGEMENT: Amprenavir may be taken with or without food, but should not be taken with a high-fat meal.

References (2)
  1. (2001) "Product Information. Agenerase (amprenavir)." Glaxo Wellcome
  2. Demarles D, Gillotin C, Bonaventure-Paci S, Vincent I, Fosse S, Taburet AM (2002) "Single-dose pharmacokinetics of amprenavir coadministered with grapefruit juice." Antimicrob Agents Chemother, 46, p. 1589-1590
Moderate

aspirin food

Applies to: Alka-Seltzer Lemon-Lime (aspirin/citric acid/sodium bicarbonate)

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
Minor

aspirin food

Applies to: Alka-Seltzer Lemon-Lime (aspirin/citric acid/sodium bicarbonate)

One study has reported that coadministration of caffeine and aspirin lead to a 25% increase in the rate of appearance and 17% increase in maximum concentration of salicylate in the plasma. A significantly higher area under the plasma concentration time curve of salicylate was also reported when both drugs were administered together. The exact mechanism of this interaction has not been specified. Physicians and patients should be aware that coadministration of aspirin and caffeine may lead to higher salicylate levels faster.

References (1)
  1. Yoovathaworn KC, Sriwatanakul K, Thithapandha A (1986) "Influence of caffeine on aspirin pharmacokinetics." Eur J Drug Metab Pharmacokinet, 11, p. 71-6

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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