Can amitriptyline interact with clonidine?/nBacktround: An heroin addict patient has been treated w

Fråga: Can amitriptyline interact with clonidine? Backtround: An heroin addict patient has been treated with amitriptyline (Tryptizol) 100 mg daily for 2 weeks for depression. Treatment of opioid abstinence reaction with clonidine is intended.

Sammanfattning: It is reasonable to expect an interaction on the receptor level to occur between clonidine and amitriptyline. The therapeutic effect of concomitant use has not been reported in opiate withdrawal. Although the combination seems questionable from a theoretic point of view we see no reason why it could not be tried.

Svar: Alpha-2-adrenoceptors have been implicated in the actions of clonidine and tricyclic antidepressants (TCA). Clonidine in opioid abstinence reaction activates alpha-2-receptors causing hyperpolarization of the neuron membrane in the locus coeruleus (LC), which is accompanied by inhibition of action potential generation. The inhibition of the activity of the LC will secondarily reduce the norepinephrine-induced activation of central, postsynaptic alpha-1-adrenoceptors, decreasing the amplification of incoming sensory signals to the CNS (1) TCA, in depression by reuptake inhibition increase synaptic availability of norepinephrine, which exerts through axon collaterals and alpha-2-receptor mediated feedback inhibition on the cells in the locus coeruleus (2).

Inhibition of the hypotensive effect of clonidine by desipramine, probably through an alpha-adrenoceptor mediated mechanism, has been observed in depressed (3) and hypertensive (4) patients on chronic treatment.