Schizophrenia side effects

Naloxone is approved for use in neonates to reverse respiratory depression induced by maternal opioid use. In addition, naloxone has been used to improve circulation in patients in shock, an effect related to blockade of endogenous opioids. Other experimental and less well documented uses for naloxone include reversal of coma in alcohol overdose, appetite suppression, and alleviation of dementia from schizophrenia. Side effects of naloxone are minor. 

Chlorpromazine had been shown to produce a tranquil state in animals and since it had a similar effect in humans it became known as a major tranquiliser but the term is rarely used today. Sometimes the drugs used to treat schizophrenia are called anti-psychotics but more commonly neuroleptics. Leptic means to activate (take hold of) and in animals these compounds produce a state of maintained motor tone known as catalepsy. This is an extrapyramidal effect and in schizophrenics the neuroleptics can cause a number of extrapyramidal side-effects (EPSs) including Parkinsonism. The new term neuroleptic is unsatisfactory as a description of clinically useful drugs. It really describes a condition (catalepsy) seen in animals and is more indicative of a compound s ability to produce EPSs than to treat schizophrenia. Antipsychotic is more descriptive but could imply a more general efficacy in psychoses than is the case. It would seem more appropriate to call a drug that is used to treat schizophrenia an antischizophrenic just as we use the terms antidepressant or antiepileptic irrespective of how the drug works. Despite such personal reservations, the term neuroleptic will be used in this text. 

Figure 17.9 Schematic representation of the proposed activity profile of an ideal neuroleptic. The figure shows DA pathways to the prefrontal cortex, mesolimbic nucleus accumbens and striatum the effects required for an ideal drug on the DA influence and symptoms there and to what extent they are met by most typical and atypical neuroleptics and by clozapine. Note that while all atypical neuroleptics induce few extrapyramidal w side-effects (EPSs) few of them, apart from clozapine, have much beneficial effect in overcoming negative symptoms of schizophrenia ...

These symptoms are alleviated by administering levodopa (L-dopa), a precursor for dopamine. L-dopa is taken up by the axon terminals of dopaminergic neurons and used to form dopamine. Interestingly, in some patients, a side effect of dopamine replacement therapy is the development of symptoms characteristic of schizophrenia. (Recall that this mental disorder is caused by overactive dopaminergic neurons.) On the other hand, drugs used to treat schizophrenia — dopamine receptor antagonists — may elicit symptoms of Parkinson s disease. 

Reserpine inhibits the synaptic vesicular storage of the monoamines dopamine, serotonin and noradrenaline. As a result they leak out into the cytoplasm where they are inactivated by monoamine oxidase this causes their long-lasting depletion. The resulting low levels of dopamine underlie the antipsychotic actions of reserpine (Chapter 11), whereas the reduced noradrenaline levels underlie its antihypertensive actions. Finally, the resulting low levels of serotonin and noradrenaline mean that reserpine also induces depression. These severe side effects mean that reserpine is no longer used clinically as a treatment for schizophrenia (Chapter 11). 

For more information on the side effects, pharmacokinetics, and drug interactions of specific agents, refer to Chap. 71 on Schizophrenia, Chap. 70 on Major Depressive Disorder, and Chap. 52 on Epilepsy. 

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