Inhibitors norepinephrine-selective contrasted

Reboxetine. Reboxetine (21) is a norepinephrine-selective reuptake inhibitor that lacks affinity for most of the monoamine receptors. It thus does not exhibit the typical side-effect profile of the tricyclics. Nevertheless, side effects include increased sweating, postural hypotension (leading to dizziness), dry mouth, constipation, blurred vision, impotence, and dysuria. Tachycardia and urinary retention have also been reported (59). There is no evidence of cardiotoxicity and sexual dysfunction seems to be rare. In contrast to some of the earlier tricyclics that are sedative, reboxetine is nonsedating and can cause insomnia (60,61).. 

The selective serotonin-reuptake inhibitors (SSRI) are a new group of chemically unique antidepressant drugs that specifically inhibit serotonin reuptake (see Figure 12.3). This contrasts with the tricyclic antidepressants that nonselectively inhibit the uptake of norepinephrine, and serotonin, and block muscarinic, H histaminic and a -adrenergic receptors. Compared with tricyclic antidepressants, the SSRIs cause fewer anticholinergic effects and lower cardiotoxicity. However, the newer serotonin reuptake inhibitors should be used cautiously until their long-term effects have been evaluated. 

Deprenyl (we used the racemic compound under the code name E-250 in the first series of experiments) proved to be a compound with a peculiar pharmacological spectrum. We described it in our first paper as a new spectrum psychic energizer (Knoll et al. 1965). I selected this compound for further development because I was fascinated by the finding that in contrast to MAO inhibitors, which potentiated the blood pressure increasing effect of amphetamine, a releaser of norepinephrine from their stores in the noradrenergic nerve terminals, E-250 inhibited it (see Fig. 1 in Knoll et al. 1965). Based on this observation we analyzed this peculiar behavior in more detail. As I expected, the studies revealed that deprenyl, in contrast to the known MAO inhibitors, did not potentiate the effect of tyramine but inhibited it. This effect of deprenyl was first demonstrated in a study performed on cats and on the isolated vas deferens of rats. The hope was expressed in this paper that this... 

Atomoxetine, a selective norepinephrine reuptake inhibitor, is the first nonstrmulant approved by the Food and Drug Administration (FDA) for the treatment of ADHD. In contrast to the stimulants, it has no apparent abuse potential and is not a controlled substance. Placebo-controlled, short-term trials (6 to 12 weeks) have shown that atomoxetine is effective in reducing ADHD symptoms in children, teens, and adults. It is not clear whether it is as effective as the stimulants, although one preliminary open study suggested comparable efficacy with methylphenidate. ... 

This diverse collection has been grouped together mostly because they do not operate as selective serotonin reuptake inhibitors. Instead, each one interacts differently with neurotransmitters that are tied to depression serotonin, norepinephrine, or dopamine. For instance, one of the more popular non-SSRIs, Effexor (venlafaxine), selectively inhibits the uptake of serotonin and norepinephrine, acting on the same molecular machinery as tricyclic antidepressants (TCAs). But, in contrast to TCAs, Effexor shows no affinity for other neurotransmitter receptors and thus has far fewer side effects than the... 

Tricyclics modify peripheral sympathetic effects in two ways through blockade of norepinephrine reuptake at neuroeffector junctions and through alpha adrenoceptor blockade. Sedation and atropine-like side effects are common with tricyclics, especially amitriptyline. In contrast to sedative-hypnotics, tricyclics lower the threshold to seizures. The answer is (B). Selective serotonin reuptake inhibitors cause sexual dysfunction in some patients, with changes in libido, erectile dysfunction, and anorgasmia. Tricyclic antidepressants may also decrease libido or prevent ejaculation. Of the heterocyclic antidepressants bupropion is the least likely to affect sexual performance. The drug is also used in withdrawal from nicotine dependence. The answer is (B). 

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