Concomitant administration of reserpine with tricyclic antidepressants has been beneficial in treating depression refractory to antidepressants alone, but in some cases, CNS excitability has been reported. In general, reserpine and tricyclic antidepressants should not be administered together. Because reserpine can decrease dopamine stores, it can antagonize the effects of levodopa. Dosage adjustments of one or both agents may be required when administering these drugs together. Patients receiving these agents concomitantly should be monitored closely to ensure that the desired antihypertensive effect is achieved.
Reserpine can antagonize the inhibitory effects of anticholinergic agents on gastric acid secretion.
The use of estrogens can increase fluid retention and increase blood pressure, thereby antagonizing the antihypertensive effects of reserpine. Concomitant use of reserpine with sympathomimetics, such as cocaine, dobutamine, dopamine, norepinephrine, epinephrine, metaraminol, methoxamine, phenylephrine, phenylpropanolamine, or ephedrine, can potentiate the vasopressor effects of these agents, antagonizing the antihypertensive effects of reserpine. The mechanism of this interaction is believed to involve reserpine-induced inhibition of the uptake of the sympathomimetic drug by adrenergic neurons, possibly resulting in hypertension and cardiac arrhythmias. Adverse CNS effects, including fatigue, dizziness, and drowsiness or lethargy, can occur during reserpine therapy. Mental depression can potentially be severe and can occur in any patient receiving the drug.