Drugs used to treat schizophrenia

There are two main types of dopamine receptor the Di type, which includes Di and D5, and is excitatory and the D2 type, which includes D2, D3 and D4, and is inhibitory. The significance of different types of dopamine receptors is still unclear, but drugs that are effective in schizophrenia appear to have an affinity for D2 type receptors. 

Anti-psychotic drugs are used in the treatment of schizophrenia and there are many in use. The choice of drug depends on the severity of the condition and the diagnosis of positive or negative symptoms. Other factors to take into consideration are whether sedation is required and how susceptible the individual is to Parkinsonian (extra-pyramidal) side effects. Most drugs are more effective at relieving the positive symptoms and all provide better results in acute schizophrenia. Long-term treatment may be necessary to prevent relapse and chronic illness. Withdrawal of treatment must be cautious to prevent relapse. 

There can be difficulty maintaining treatment if the patient is uncooperative, forgetful or does not take their drugs as prescribed. Depot preparations are sometimes used for such patients. 

Older anti-psychotic drugs are classified according to their chemical structure, while the newer ones are known as atypical anti-psychotics. The main distinction is that the newer drugs produce fewer motor side effects. (See Table 11.5). 

Phenothiazines were developed after it was noticed that the antihistamine, promethazine had a sedative action. 

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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. 

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. 

These are the newer drugs used to treat schizophrenia. Atypical anti-psychotic drugs are recommended for newly diagnosed schizophrenics and those who cannot tolerate other drugs or who are not getting adequate control from other drugs. 

Poly(vinylacetal diethylaminoacetate) (AEA) was used to coat mont-morillonite (MMT)-based nanohybrid material to achieve both taste masking and solubility enhancement of aripiprazole (APZ), a drug used to treat schizophrenia. Since APZ is a cationic substance, it easily intercalates between the layers of MMT, as found from XRD measurements, and is not released into deionized water, which is desired for taste masking, while its release profile in SGF is comparable to that of a commercial drug, Abilify . A significant increase in the bioavailability compared to Abilify vras also found. 

The role that dopamine plays in regulating mood and emotional stability can be at least partially grasped by examining dopamine s role in schizophrenia and drug addiction. Schizophrenia is a disorder characterized by delusions, hallucinations, withdrawal from external reality, and emotional unresponsiveness. The dopamine theory of schizophrenia, proposed in 1965, attributes the disorder to elevated brain concentrations of dopamine or to a hypersensitivity of dopaminergic receptors, especially the D2 and D4 receptor subtypes. Several drugs used to treat schizophrenic patients bind to D2 and D4 receptors and block the dopaminergic response. 

There Is abundant evidence chat medication with anticholinergic drugs Is contraindicated In human tardive dyskinesia (302-309). Burnett et al. (308) found chat the Improvement In tardive dyskinesia after discontinuance of the anticholinergic drug, when both an anticholinergic compound and a neuroleptic drug had been used to treat schizophrenia, was not due to any change In the patients serum concentration of... 

Antipsychotics are used to treat schizophrenia, schizoaffective states, Tourette syndrome, preoperative j sedation, drug- or radiation-induced emesis, and neuroleptic anesthesia and are used for the initial management of bipolar affective disorder. j... 

The actions and reactions within the brain are complex, and it follows that medications designed for one purpose can affect something else. As an example, psychiatrists have discovered that drugs designed to treat schizophrenia can also be useful in manic depression. Although the exact... 

Dopamine has also been identified as the neurotransmitter that produces the feelings of well-being and reward associated with drug addiction (see The World of Chemistry, Section 17.8). Drugs that block dopamine receptors have been used to treat schizophrenia, which is, however, a complex condition not attributable solely to dopamine activity. 

Ability is the trade name for aripiprazole, a drug used to treat depression, schizophrenia, and bipolar disorders, (a) Rank the N atoms in aripiprazole in order of increasing basicity, (b) What product is formed when aripiprazole is treated with HCI ... 

Perturbation of the 5-HT system can elicit changes in a wide variety of behaviors. Furthermore, drugs that act on serotonergic neurons and their receptors are used to treat diseases such as depression, anxiety disorders and schizophrenia. Thus, 5-HT has been implicated in the regulation of many behaviors and physiological processes. The involvement of 5-HT in three areas - neuroendocrine function, circadian rhythms and feeding behavior - will be highlighted for illustrative purposes. 

Dopamine is a major catecholamine neurotransmitter in the central nervous system (37) that is involved in the neuroregulation of locomotor activity, emotion, and neuroendocrine secretion (38,39). Clinically, dopaminergic drugs are used to treat Parkinson s disease and schizophrenia by activating or blocking dopamine receptors, respectively (40). 

The minor tranquilizers include a variety of compounds used to treat anxiety, tension, irritability, and stress. This is in contrast to the major tranquilizers which are found in the treatment of overt mental disease such as schizophrenia and manic-depression. The terms minor and major should not be construed to refer to the relative toxicity of these drugs. All are CNS depressants and this pharmacological class are potentially lethal. 

These drugs are used to treat serious mental disease such as the manic phase of manic depression, organic pyschosis, paranoia, or schizophrenia. They are also called antipsychotics or neuroleptics. 

Antipsychotic drugs used to successfully treat schizophrenia block central dopamine receptors to some extent (Fig. 8-1).19,23 These drugs share some structural similarity to dopamine, which allows them to bind to the postsynaptic receptor, but they do not activate it. This action effectively blocks the receptor from the effects of the released endogenous neurotransmitter (see Fig. 8-1). Any increased activity at central dopamine synapses is therefore negated by a postsynaptic receptor blockade. 

The agents used in treating schizophrenia are most successful in treating the positive symptoms negative symptoms, such as apathy and social withdrawal, seem to be less responsive to current drug treatment. 

Mirtazapine is a tetracyclic antidepressant, similar to mianserin, and is a potent 5-HT2a/2c receptor antagonist. It has been successfully used to treat akathisia. In a doubleblind, placebo-controlled study in 26 patients with schizophrenia who were receiving neuroleptic drugs, mirtazapine 15 mg/day for 5 days was associated with less akathisia (227). 

Haloperidol (brand name Haldol) A high-potency antipsychotic drug used for the treatment of schizophrenia that can also be used to treat the neurological condition of Tourette s syndrome, which involves both motor and vocal tics. 

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