Drug Interactions between Alka-Seltzer Lemon-Lime and ticlopidine

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.

GENERALLY AVOID: Ticlopidine may potentiate the effect of aspirin on collagen-induced platelet aggregation. Other salicylates that also inhibit platelet aggregation may be similarly impacted. An increased risk of bleeding should be anticipated, especially in patients with a history of gastrointestinal (GI) ulceration or bleeding. Conversely, aspirin does not alter the ticlopidine-mediated inhibition of adenosine diphosphate-induced platelet aggregation.

MANAGEMENT: The safety of concomitant use of ticlopidine with aspirin or other platelet-inhibiting salicylates has not been established. Ticlopidine labeling recommends against long-term coadministration with aspirin. However, ticlopidine (250 mg twice daily) may be given with antiplatelet dosages of aspirin for up to 30 days following successful coronary artery stent implantation to reduce the risk of blood clots forming inside the stent. Close monitoring for bleeding complications, particularly GI bleeding, is advised during treatment.

Coadministration of oral medications that contain magnesium, aluminum, calcium, or sodium (i.e., antacids) has decreased ticlopidine serum concentrations by 18%. Administration of these drugs should be separated by at least three hours.