These drugs have been called neuroleptics, antischizophrenic drugs, antipsychotic drugs, and major tranquilizers. All these terms are synonymous; neuroleptic and antipsychotic are the most common. These drugs are not curative (because they do not eliminate the fundamental thinking disorder), but they often permit the patient to function more normally.
All of the neuroleptics are
These actions produce the side effects of the drugs.
If you know which receptors these drugs block, you can predict all of the actions and side effects of these drugs. The antimuscarinic actions produce dry mouth, constipation, urinary retention, blurred vision, and so on. The α-antagonism produces orthostatic hypotension, and the H1-antagonism produces sedation.
These drugs were organized according to their chemical structure. I do not recommend this method unless you have decided to memorize all of the structures. I recommend dividing these drugs into two groups: the older, so-called typical antipsychotics and the newer atypical drugs. The newer “atypical” drugs are now the drugs of choice for the treatment of schizophrenia, so the term “atypical” is a misnomer. The older drugs are also called “first generation” and the newer drugs “second generation.” This makes much more sense. Name recognition here is sometimes a problem, but notice that most of the typical neuroleptics end in “-azine.” A number of the second-generation drugs end in “–peridone.”
All neuroleptics are dopamine blockers (D2), but the atypical drugs (second generation) also block 5-HT2A receptors.
|Typical Neuroleptics (First Generation) ||5-HT-DA Antagonists (Second Generation) |
You now know the most fundamental information about the drugs in this group. You need only add a little bit more, depending on how much trivia you want to know.
TYPICAL ANTIPSYCHOTICS (FIRST GENERATION)
All the drugs in this group have equal efficacy; they vary only in potency and side effects.
REMINDER: The typical antipsychotics block dopamine, muscarinic cholinergic, α-adrenergic, and H1-histaminergic receptors.
The dopamine antagonism is believed to produce the antipsychotic effect. It also produces some endocrine effects. Remember that dopamine inhibits prolactin release. Thus, an antagonist at the dopamine receptor results in an increase in prolactin release. This in turn leads to lactation. Most of the neuroleptics, except thioridazine, have antiemetic effects that are mediated by blocking D2 receptors of the chemoreceptor trigger zone in the medulla.
All of these drugs produce extrapyramidal effects, including parkinsonism, akathisia, and tardive dyskinesia.
The extrapyramidal effects of these drugs are presumably caused by blocking of dopamine receptors in the striatum (basal ganglia). Extrapyramidal ...