Nortriptyline action

Older- tricyclic antidepressants are set in italics. The specificity of action of tricyclic antidepressants (in particular of amitritpyline, imipramine, doxepine, nortriptyline, duloxetine, maprotiline) is limited because at therapeutic levels these drugs also block recqDtors (Hrhistamine, aradrenergic, muscarinic). 

Nortriptyline. Nortriptyhne, a tricychc antidepressant, has been shown in double-blind, placebo-controlled randomized trials to be superior to placebo for smoking cessation (Prochazka et al. 1998). Nortriptyline appears to have efficacy comparable to that of bupropion for smoking cessation (Hall et al. 2002). The efficacy of this agent may be improved with more intensive behavioral therapies (Hall et al. 1998). Nortriptyline s mechanism of action is thought to relate to its noradrenergic and serotonergic reuptake blockade, because these two neurotransmitters have been implicated in the neurobiology of nicotine dependence. Side effects of nortiptyline are typical of tricyclic antidepressants and include dry mouth, blurred vision, constipation, and orthostatic hypotension. Nortriptyline appears to have some utility for smokers with a past history of major depression, and it can be recommended as a second-... 

All TCAs are either secondary- or tertiary-amines of a dibenzazepine nucleus (Fig. 20.3), and they all inhibit neuronal reuptake of noradrenaline and/or 5-HT but are much less potent as dopamine reuptake blockers. A common claim is that secondary amines (e.g. desipramine) are preferential inhibitors of noradrenaline uptake whereas the tertiary derivatives (e.g. imipramine, doxepin and amitryptyline) preferentially inhibit 5-HT uptake. However, when Richelson and Pfenning (1984) actually compared the effects of a wide range of antidepressants on the synaptosomal uptake of [ H]monoamines in vitro, and compared their A s, instead of merely ranking /C50S collected from different studies, they found that tertiary- and secondary-substituted compounds were equi-potent inhibitors of [ H]noradrenaline uptake. Moreover, all the TCAs turned out to be more potent inhibitors of [ H]noradrenaline than of [ H]5-HT uptake. Tertiary amines are even less convincing inhibitors of 5-HT reuptake in vivo, because any such action is diminished by their metabolism to secondary amines (e.g. imipramine to desipramine amitriptyline to nortriptyline). Only clomipramine retains any appreciable 5-HT uptake blocking activity in vivo with (an unimpressive) five-fold selectivity for 5-HT versus noradrenaline. 

Tricyclic drugs have, as the name implies, a three-ring structure, and interfere with reuptake of norepinephrine and/or serotonin into axon terminals. Tricyclic drugs include imipramine (Tofranil), amitriptyline (Elavil), clomipramine (Anafranil), and nortriptyline (Pamelor, Aventil). Tricyclics have the occasional but unfortunate cardiovascular side effects of arrhythmia and postural hypotension. Newer, nontricyclic antidepressants have been developed that are collectively referred to as SSRIs. These have a potent and selective action on serotonin, and lack the cardiovascular side effects of the tricyclics. These include fluoxetine (Prozac), paroxetine (Paxil), sertraline (Zoloft), and fluvoxamine (Luvox). A fifth SSRI, citalopram (Celexa) has been used in Europe and has recently been approved in the United States. Venlafaxine (Effexor) blocks reuptake of norepinephrine and serotonin, while bupropion (Wellbutrin) acts on both dopamine and norepinephrine. 

A few modifications of the described methods have been suggested for making nortriptyline [27-32], Nortriptyline is a drug with a relatively short latent period of action. It is practically devoid of sedative effects. It is used in manic-depressive psychoses, in all forms of endogenous depression, and also in major depressive conditions. The most common synonyms of nortriptyline are aventyl, nortrilen, motival, vivactil, and pamelor. 

With regard to its effects on cognitive performance in the target population, the SSRI sertraline appears to be the most thoroughly studied newer antidepressant. Lane and O Hanlon (1999) listed three controlled clinical studies with fluoxetine and three with sertraline however, all three trials with fluoxetine and one of the trials with sertraline were not sufficiently powered to demonstrate reliable differences between treatments. One of the two adequately powered studies, a comparison between nortriptyline and sertraline in elderly depressed patients (Bondareff et al., 2000 see Box 7.3), supports the notion that antidepressants with anticholinergic action (such as nortriptyline) are similarly... 

Secondary amine TCAs (e.g., nortriptyline, desipramine) are better tolerated and somewhat safer than their tertiary amine parent compounds (e.g., amitriptyline, imipramine) (407, 408). This is due to differences in the relative potencies of several pharmacological actions, which include their binding affinity for the following ... 

Several antidepressants share the ability to block serotonin 2A receptors as well as serotonin reuptake. In fact, some of the tricyclic antidepressants, such as amitriptyline, nortriptyline, doxepine, and especially amoxapine, have this combination of actions at the serotonin synapse. Since the potency of blockade of serotonin 2A receptors varies considerably among the tricyclics, it is not clear how important this action is to the therapeutic actions of tricyclic antidepressants in general. 

FIGURE 7—40. Adrenergic combo 1 Bupropion plus norepinephrine reuptake inhibitor (NRI). Here the NE actions of bupropion are double-boosted by the NRI (either selective reboxetine or nonselective desipramine, maprotilene, nortriptyline, or protriptyline). Dopamine is single-boosted by bupropion only. 

Bupropion, reboxetine, nortriptyline, desipramlne, maprotlllne, atomoxetine (all potentially powerful enhancers of noradrenergic action, but observe for activation of bipolar disorder and suicidal Ideation)... 

Amitriptyline is most frequently used, starting with 10 mg at night increasing to 75 mg. Nortriptyline is better tolerated by some patients. Their general action is to inhibit noradrenaline (norepinephrine) re-uptake by nerve terminals and benefit in neuropathic pain may follow enhanced activity in noradrenergic pain inhibitory paths in the spinal cord. 

Tricyclic antidepressants. Imipramine, amitriptyline and nortriptyline are effective, especially for nocturnal but also for daytime incontinence. Their parasympathetic blocking (antimuscarinic) action is probably in part responsible but imipramine... 

HT, antagonist with antidepressant activity (123) it binds with high affinity (if < 10 nM) at 5-HT, receptors (124). Hence, trazodone (24), nefazodone (16), and mianserin (27) represent atypical antidepressants that have in common a high affinity for S-HTgA receptors and S-HTg antagonist action. It might be noted that certain tricyclic antidepressants also bind at 5-HT, receptors imipramine (11), desipramine (6), nortriptyline (17), and maprotiline (13), for example, bind with submicromolar Ki values (124) (Table 8.6). 

Nortriptyline appeared to be somewhat more consistently effective than the other agents, except in involutional melancholia. Particularly impressive was the improvement rate in the manic depressive group (87% vs. 69% for the others). Side effects were generally mild, although dryness of the mouth occurred in 52% of the patients. Somnolence occurred in only 8% of the patients and, as with desipramine, the secondary amine congener appeared to be less of a central depressant. Onset of action was fairly prompt. Initial improvement occurred after 7 to 10 days. 

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