Synthesis of Some Nefopam Analogues as Potential Analgesics

Some derivatives of the non-narcotic analgesic nefopam containing amidine and guanidine substituents have been prepared and their analgesic activity assessed by their ability to block the uptake of noradrenaline. The compounds have been shown to inhibit noradrenaline uptake but they also display possible α1 antagonist activity at higher concentration. An ester derivative was also active and was more selective as it did not exhibit α1 adrenoreceptor antagonism.

Different roles for serotonin in anti-obsessional drug action and the pathophysiology of obsessive-compulsive disorder

Background There is a major role for serotonin in the mechanism of anti-obsessional drug action. Drugs that block uptake of noradrenaline are not effective in the treatment of obsessive-compulsive disorder (OCD), while drugs that potently bock serotonin reuptake are effective. While enhancement of serotonin neurotransmission is clearly involved in the treatment of OCD, the role of serotonin in the pathophysiology of OCD is less clear.Method This paper provides a brief, focused review ofthe literature regarding treatment of OCD, the effects of drugs with selective action at various serotonin receptors and results of neurotransmitter depletion studies in patients with OCD.Results Some patients with OCD may experience remission of OCD symptoms during intoxication with psychedelic drugs that have potent 5-HT2A/2c agonist activity. These findings, coupled with results from serotonin depletion studies in depressed and OCD patients, suggest that enhancement of serotonin neurotransmission may underlie both antidepressant and anti-obsessional drug action, although the targeted brain areas may differ.Conclusions OCD may not involve a dysfunction ofthe serotonin system. Rather, it is more likely to involve a dysfunction of specific brain circuits, particularly in the frontal cortex. Modulation of these circuits by serotonin neurons may underlie the specific action of anti-obsessional drugs.

Neuronal Re-Uptake of Noradrenaline by Sympathetic Nerves in Humans

1. Plasma concentrations of [3H]dihydroxyphenylglycol, the intraneuronal metabolite of noradrenaline, were examined during intravenous infusion of [3H]noradrenaline in 43 subjects, to assess the nature of its formation. Noradrenaline re-uptake by sympathetic nerves was estimated in 11 subjects from the effects of neuronal uptake blockade with desipramine on noradrenaline clearance and plasma concentrations of [3H]dihydroxyphenylglycol and endogenous dihydroxyphenylglycol. In seven subjects noradrenaline re-uptake and spillover into plasma were examined before and during mental arithmetic or handgrip exercise. 2. During infusion of [3H]noradrenaline, plasma [3H]dihydroxyphenylglycol increased progressively, indicating its formation from previously stored [3H]noradrenaline leaking from vesicles as well as from [3H]noradrenaline metabolism immediately after removal into sympathetic nerves. Thus, to estimate noradrenaline reuptake, the amount of [3H]dihydroxyphenylglycol derived from [3H]noradrenaline metabolized immediately after removal into the sympathetic axoplasm must be isolated from that derived from [3H]noradrenaline sequestered into vesicles. 3. At rest in the supine position the rate of noradrenaline re-uptake was 474 ± 122 pmol min−1 kg−1, 9.5-fold higher than the rate of spillover of noradrenaline into plasma (49.6 ± 6.4 pmol min−1 kg−1). Noradrenaline reuptake and spillover into plasma were both increased during mental arithmetic and isometric handgrip exercise.