Drug Interactions between Aptivus and aspirin / calcium carbonate

MONITOR CLOSELY: Theoretically, tipranavir may potentiate the risk of bleeding in patients treated with agents that affect hemostasis such as anticoagulants, platelet inhibitors, thrombin inhibitors, thrombolytic agents, high supplemental dosages of vitamin E, or agents that commonly cause thrombocytopenia. Tipranavir has been shown to inhibit human platelet aggregation in vitro at levels consistent with exposures observed in patients receiving tipranavir/ritonavir. Cases of intracranial hemorrhage, some fatal, have been reported during postmarketing use. However, many of these patients had other medical conditions or were receiving concomitant medications that may have caused or contributed to these events. No pattern of abnormal coagulation parameters has been observed in patients in general, or preceding the development of intracranial hemorrhage.

MANAGEMENT: Caution is advised if tipranavir/ritonavir is used in combination with other drugs that affect hemostasis. Patients should be advised to promptly report any signs of bleeding to their physician, including pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, increased menstrual flow, vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or brown urine, or red or black stools.

Switch to consumer interaction data

MONITOR: Chronic administration of antacids may reduce serum salicylate concentrations in patients receiving large doses of aspirin or other salicylates. The mechanism involves reduction in salicylate renal tubular reabsorption due to urinary alkalinization by antacids, resulting in increased renal salicylate clearance. In three children treated with large doses of aspirin for rheumatic fever, serum salicylate levels declined 30% to 70% during coadministration with a magnesium and aluminum hydroxide antacid. Other studies have found similar, albeit less dramatic results. Antacids reportedly have no effect on the oral bioavailability of aspirin in healthy adults. However, administration of antacids containing either aluminum and magnesium hydroxide or calcium carbonate two hours before aspirin dosing led to reduced absorption of aspirin in uremic patients.

MANAGEMENT: Patients treated chronically with antacids (or oral medications that contain antacids such as didanosine buffered tablets or pediatric oral solution) 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.

Switch to consumer interaction data

ADJUST DOSING INTERVAL: Concurrent administration of antacids or other agents with acid-neutralizing effects may decrease the oral bioavailability of tipranavir and reduce its concentrations in plasma. The mechanism of interaction has not been described. When tipranavir (in combination with low-dose ritonavir) was coadministered with 20 mL of an aluminum- and magnesium-based liquid antacid, tipranavir peak plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) were reduced by 25% to 29%. The clinical significance of these changes is unknown. However, subtherapeutic antiretroviral drug levels may lead to reduced viral susceptibility and development of resistance.

MANAGEMENT: Consideration should be given to separating tipranavir/ritonavir dosing from antacid administration to prevent reduced absorption of tipranavir.

Switch to consumer interaction data