<p>The possibility of interactions with other medicinal products administered concurrently should be considered, particularly when the main route of elimination is active renal secretion. Administration of trimethoprim/sulfamethoxazole 160 mg/800 mg results in a 40% increase in Lamivudine exposure. Lamivudine and zalcitabine may inhibit the intracellular phosphorylation of one another. Therefore, use of Lamivudine in combination with zalcitabine is not recommended.</p>