Serial application of clonidine tests during antidepressive treatment with chlorimipramine

In a controlled 3 week trial on 20 endogenous depressive inpatients refractory to outpatient treatment and treated with two different types of antidepressive medication (chlorimipramine vs. chlorimipramine combined with haloperidol in the first six days), the clonidine test was performed repetitiously to analyse changes of the functional state of central noradrenergic synapses. In nearly all cases the GH response after clonidine was blunted at the beginning and at the end of the trial; in a few cases a response was observed after 8 days of treatment. The data are discussed under the hypothesis of a hyposensitivity of central alpha-receptors in endogenous depressives and under the aspect of drug induced changes: at first inhibition of noradrenaline reuptake, later on adaptive down-regulation of alpha-receptors. There was no evidence for the expected haloperidol-induced supersensity of central adrenergic receptors.