Neuroleptics tricyclic

First-pass metabolism (first-pass effect) The passage of the drug from the portal circulation into hepatocytes and conversion there into metabolites. These metabolites may have a pharmacological profile different from that of the parent drug. They are typically then excreted by the hepatocytes into the biliary system and pass back into the small bowel where enterohepatic recirculation may occur (e.g., benzodiazepines, bupropion, nefazodone, neuroleptics, tricyclic antidepressants). 

In our model, we have indicated that atypical antipsychotics (12) (sulpiride, metoclopramide, molindone, and Ro 22-1319) differ from classical neuroleptics (tricyclics, butyrophenones, butaclamol, diphenyl-piperidines) by lacking a lipophilic functional group on the basic nitrogen that could extend into the auxiliary binding site identified in our model. The absence of this lipophilic functionality may now be stated to be the characteristic which distinguishes selective D-2 dopamine receptor antagonists from non-selective antagonists. 

Drugs that are normally extensively eliminated in first-pass through the liver appear in higher concentration in the systemic circulation and persist in it for longer. There is thus particular cause initially to use lower doses of most neuroleptics, tricyclic antidepressants and cardiac antiarrhythmic agents. 

To anticipate briefly, shortening the length of the side chain in the phenothiazines from three to two carbon atoms changes I he activity of the products from neuroleptics to antihistaminic iigents. A rather similar effect is seen in the tricyclic antidepressants. Reaction of ketone, 27, with the Grignard reagent I rom 4-chloro-l-methylpipyridine (35) affords the tertiary alco-liol, 36. Dehydration gives the antihistamine, cyproheptadine (37). ... 

The tricyclic antidepressants (TCAs) derive their name from their three-ringed molecular structure (Fig. 20.3) and emerged, in 1958, from a search for better neuroleptics than chlopromazine among the phenothiazines. The prototype, imipramine, turned out to be ineffective in treating the positive symptoms experienced by schizophrenics but it did relieve their depression (negative symptoms). In fact, imipramine is still the standard agent against which novel antidepressants are compared in clinical trials. 

Non-compliance issues appear more prevalent in some non-Western cultures. One study in South Africa revealed non-compliance rates to oral neuroleptics in two-thirds of Black patients and one-half of colored patients compared to only one-quarter of Caucasians (Gillis.Trollip, Jakoet etal., 1987). Cultural and communication factors were considered to be significant barriers apart from those related to cost and social factors. Kinzie et al. (1987) reported that despite prescribing adequate doses of tricyclic antidepressants (TCAs) to depressed Asian refugees,... 

The answer is e. (Hardman, pp 415, 442—443.) Tardive dyskinesia is an adverse effect of neuroleptics, not tricyclic, antidepressants. 

Non-motor signs of the disorder are also treatable with symptomatic medications. The frequent mood disorder can be treated with standard antidepressants, including tricyclics (such as amitryptiline) or serotonin reuptake inhibitors (SSRIs, such as fluoxetine or sertraline). This treatment is not without risks in these patients, as it may trigger manic episodes or may even precipitate suicide. Anxiety responds to benzodiazepines, as well as to effective treatment of depression. Long-acting benzodiazepines are favored over short-acting ones because of the lesser abuse potential. Some of the behavioral abnormalities may respond to treatment with the neuroleptics as well. The use of atypical neuroleptics, such as clozapine is preferred over the typical neuroleptics as they may help to control dyskinesias with relatively few extrapyramidal side-effects (Ch. 54). 

In accordance with the structure of the BBB as a double Upid bilayer, classical neuroactive drugs such as benzodiazepines, neuroleptics and tricyclic antidepressive agents, are all small lipophilic molecules. These small molecular weight neuropharmaceuticals were selected by a trial and error approach because their structural characteristics allow for diffusion-mediated,... 

Central Motor restlessness, progressing to maniacal agitation, psychic disturbances, disorientation, and hallucinations. Elderly subjects are more sensitive to such central effects, in this context, the diversity of drugs producing atropine-like side effects should be borne in mind e.g., tricyclic antidepressants, neuroleptics, antihistamines, antiarrhythmics, antiparkinsonian agents. 

The first psychotropics of the modern era (e.g., lithium, neuroleptic antipsychotics, tricyclic and monoamine oxidase inhibitor antidepressants) were discovered serendipitously. These agents were not engineered to have selective actions, but instead produce a wide range of central biochemical effects and generally affect more than one neurotransmitter system simultaneously, resulting in multiple repercussions ... 

The tricyclic antidepressants (Table 6—5) were so named because their organic chemical structure contains three rings (Fig. 6—25). The tricyclic antidepressants were synthesized about the same time as other three-ringed molecules that were shown to be effective tranquilizers for schizophrenia (i.e., the early antipsychotic neuroleptic drugs such as chlorpromazine) (Fig. 6—26). The tricyclic antidepressants were a disappointment when tested as antipsychotics. Even though they have a three-ringed structure, they were not effective in the treatment of schizophrenia and were almost... 

In addition to the stereochemical structure of the tricyclic skeleton, the conformation of the amino-substituted side chain can influence the psychotropic activity of such compounds. According to the theory of Wilhelm, transmission of the basic psychotropic activity depends largely on the constellation adopted by the side chain. However, the main psychotropic action (neuroleptic or thymoleptic) is chiefly a function of the particular stereochemistry of the tricyclic framework. 

In combination with tricyclic antidepressants, lithium is used in treating recurrent endogenous depression. In combination with neuroleptics, it is used in the management of schizoaffective disorders. In combination with neuroleptics, it is used to control schizophrenia. Lithium is also used in the case of patients with alcoholism associated with depression and has been used to correct the neutropenia that occurs during cancer chemotherapy. 

Various factors may account for the variability in response to neuroleptics. These include differences in the diagnostic criteria, concurrent administration of drugs which may affect the absorption and metabolism of the neuroleptics (e.g. tricyclic antidepressants), different times of blood sampling, and variations due to the different type of assay method used. In some cases, the failure to obtain consistent relationships between the plasma neuroleptic concentration and the clinical response may be explained by the contribution of active metabolites to the therapeutic effects. Thus chlorpromazine, thioridazine, levomepromazine (methotrime-prazine) and loxapine have active metabolites which reach peak plasma concentrations within the same range as those of the parent compounds. As these metabolites often have pharmacodynamic and pharmacokinetic activities which differ from those of the parent compound, it is essential to determine the plasma concentrations of both the parent compound and its metabolites in order to establish whether or not a relationship exists between the plasma concentration and the therapeutic outcome. 

The butyrophenones and diphenylbutylpiperidines differ from the phenothia-zines and thioxanthines in that they are not tricyclic structures. The first butyrophenone to be developed was haloperidol, and this is the most widely used, potent neuroleptic. Unlike many of the phenothiazines, these neuroleptics largely lack antihistaminic, anticholinergic and adrenolytic activity they are also non-sedative in therapeutic doses. Their potent antidopaminergic activity renders them likely to cause extrapyramidal side effects. Of the various butyrophenones shown in Figure 11.10, benperidol has been selectively used to suppress asocial sexual behaviour. 

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