Additive hypotension w/ anesth & hydrocarbon inhalation; β-adrenergic blocking agents. Reduced antihypertensive effects w/ NSAIDs (indomethacin) & sympathomimetics. Increase BP due to induced fluid retention w/ estrogen. Changes in serum conc of free unbound medications w/ highly-protein bound medications (anticoagulants, coumarin & indandione derivatives, anticonvulsants, hydantoin, NSAIDs, quinine, salicylates, sulfinpyrazone). Potentiated antihypertensive effects w/ hypotension-producing medications. Neurotoxicity w/ lithium.