Use of Antipsychotics in General Practice

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1 Date : November, 01, 2009 Publication : Medical Chronicle Page Number: Use of Antipsychotics in General Practice Page 1 / 5 Size=33SCKS$&imn OftraUftbonl 1999KSeddEserpp119999

2 Date : November, 01, 2009 Publication : M Page 2 / 5 Size=42(DX298mm Circulate Theintroducfion of cuim-ntinnal antipsychotic drugs in the IMSIK and 60s revolutionised the practice of psychiatry and. in particular, the treatment of schizophrenia and other psychoses. Patients suffering from these conditions were.tlili in l>i' dcinslitutinnaliscd and treated in a primal*) care setting for the first time. These agents are being replaced l>\ the newer atypical antipsychotics in mans parts of the world, but in countries like SA, the typical/conventional agents are still widely used to treat as arid) of psvehiatrie disorders. Recently, more primary care doctors have been able t" use the newer 'atypical' agents, especial!) since the introduction of generic versions of drugs such as risperidone. The term 'antipsychotic' is perhaps too restrictive as these agents are useful not only in the treatment Of psychotic disorders such as schizophrenia, but also in treating psychotic depression, manic episodes of bipolar mood disorder. Tou relic's syndrome, behavioural problems associated with dementia, etc. It is important that doctors using antipsychotics familiarise themselves with their mode ofaction, applications, side-effect profiles and possible dangers. Appropriate use can optimise patient functioning but inappropriate use can lead to increased morbidity. It is essential that the prescription of an antipsychotic drug be done with care. after an appropriatediagnosis has been made, and in the context of a comprehensive care plan. /. Typictil/cofwntionalantipsychotics; These drugs share the common ability to cause 'neuro- Icpsis' which is lt shared property associated with their ability to block dopamme-2 [\).) icccptors. The ability of the conventional antipsychotics to block the l>. receptors is the mode of action responsible for the relieving of the positive symptoms ol schizophrenia, such as. hallucinations and delusions. Notably, the conventional antipsychotics are largely devoid of their ability to block serotonin-2a (5-1IT,,) receptors, a keyproperty of the atypical antipsychotics. They also have anticholinergic properties. Netiro-pharnuicology: There are lour important dopamine pathways involved in the action of these agents. Blockade of the mesolimbic pathway is largely responsible for the antipsychotic effects. Blockadcoftheniesworlical pathway poses a dilemma as patients w ith schizophrenia often have an already existing dopamine deficiency in this area, causing the so-called 'negative' symptoms such as blunted affect, apathy, alogia. a\olition. anhedonia and attentional impairment - all of these may be worsened by administration of the conventional agents. Blockade of nigrostriatal pathways causes neurological effects such as acute dystonia, parkinsonism, akathisia and tardive dyskinesia (extrapyramidal effects). Blockade of the lubero-infundibuktr pathways results in hyperprolaetinaemia. and blockade of the area postrema causes antiemetic effects. In addition to blocking the I), receptors in all four dopamine pathways, conventional antipsychotics also have the ability to block muscarinic cholinergic receptors. This can cause undesirable side effects, such as dry mouth, blurred vision. constipation and cognitive blunting. Other pharmacological actions are associated with conventional antipsychotics, including generally undesired activity at u, adrenergic receptors (orthostatic hypotension and drowsiness) as well as at histamine receptors (weight gam and drowsiness). Because of the difference in affinity for certain of the above receptor types, the Readership: 11939,.- conventional antipsychotics diiier somewhat in their side-efteei profiles, even il they do not differ in their therapeutic profiles. Uses: In many countries, tlie conventional antipsychotics are used now as second-line treatment as it is held that second-generation antipsychotics (SGAs) or 'atypical' antipsychotics have a more tolerable side-effect prolile. But. in several other countries (including SA), they are still often used as first-line treatment in psychotic disorders such as schizophrenia. They are effective in the acute as well as maintenance phases of treatment of this disorder, and are probably no less effective; than turn-clozapine alypicals. An added advantage is that several agents are formulated for intramuscular administration for acute or depot use. and these drugs are generally cheaper than atypicals. In the acute phase of treatment of schizophrenia, when using conventional antipsychotics it is

3 Date : November, Publication : Medical Chronicle Page Number: best (o use an oral preparat ion }' i iiwnv lift" Of t'liiit a (niin ProfPMJouberi l'i This month's author: Or Ian Westmoiv first while try ing to establish the patient's response to the drug and observing for stile effects, in particular dangerous conditions such as malignant neurolept syndrome. It may lake Jays to weeks for patients to respond and there is considerable variation in response. Once the patient has been stabilised and it seems that the drug is tolerable, it may he prudent to transfer treatment to a depot injectable form to ensure treatment compliance in the maintenance phase. In this phase, the lowest effective dose is normally used. Conventional antipsychotics are sometimes used for the management of psychosis and behavioural disturbances in elderly patients. Thioridazine (Melleril) was commonly employed. Lin IIWMfttfV but its effect on Wood pressure and memory led lo it being discontinued. I here are studies that indicate that slow titration of haloperidol ma) be effective in doses of2 3mg daily, although careful monitoring of these patients is advised. 2. Atypical/st'cond-Kenerariunaiitipsychotksi Compared lo the traditional agents. alisc iashave a higher ratio of serotonin (5 111 ) to I), receptor blockade, and a greater specificity lor the mosolimbic than the striatal dopamine system. In recent times, the word 'atypical' has been usvd lo describe drugs that are highly selective D. blockers and are relatively selective lot I> receptors in the mesolimbic areas, those that have to page 76 Page 3 / 5 Size=29JX249mm Circulation: Readership: 11939

4 Date : November, 01, 2009 Publication : Medical Chronicle Page Number: Use of Antipsychotics in General Practice continuedfrom page 7S a high 5HT.:D, receptor-blocking ratio and have an effect on 'negative' symptoms. They generally cause fewer extrapyramidal side effects (KPSE) than most of the older drugs, but have other side effects that are of concern. Clozapine (Leponex el al) was the first of the newer-generation antipsychotics to be introduced, ft is the archetypal atypical antipsychotic that has been around since the 1960s and was withdrawn from use after an association with neutropenia (incidence 3%) and agranulocytosis (0.8%) was made. Later studies demonstrated its efficacy in treatment-resistant patients and it was reintroduced with careful haematologieal monitoring. ( lo/apinc has a broader spectrum of action compared to the conventional antipsychotics including affecting positive, negative and cognitive symptoms. Dose range: 2O0-4IH) (600)mg per day. 3. Other second-generation antipsychotics: Amisulpiride (Solian): At doses above 30()mg day, it blocks post synaptic dopamine receptors and is relatively selective lor limbic rather than striatal areas (fewer EPSHs). It is relatively free of sedation, anticholinergic side effects and postural hypotension, but like sulpiride, is a potent elevator of prolactin. Dose range: 4()0-800mg per day. available in tablet form. Risperidone (Risperdal el al) is a potent 51 IT.:D, antagonist imd is effective in treating the negative and positive symptoms of schizophrenia. In doses less than 6mg per day it is associated with fewer EPSEs and less sedation, but the drug is associated with hyperprolaclinaeiuia. page 4 / 5 Size=293XH9mm Circulation: Readership: 11939

5 Date : November, 01, 2009 Publication : Me Chemical name Phenothiazines: Chlorpromazine Ffuphenazine Trifluoperazine Prochlorperazine Clolhiapine Butyrophenone: Haloperidol Thioxanthene: Flupenthixol Zuklopenthixol Diphenylbulylpiperidine: Pimozide Trade name Largactil Moderate Stctazme etc Stemetil etc Etomine Serenace Fluanxol Clopixol Orap Anticholinergic effects Extrapyramidal side effects Dose equivalent (mg) 100 5/week (tabs); 10/week {depot) 25/week (tabs): 100/week (depot) Adopted from Stein />./. Seedal S, Niehaus IXIII ci al Psychiatric Medication in Primary ('are. Algorithms and Guidelines. T^ Edition. UniversitvofStellenbosch, Dose range: 4-8mg per da) (for behavioural disturbances "> patients with dementia - 0.5mg bn). or less). It is also available now in ;i depot injectable form (Constat - usual dose is 25mg Iwo weekly by intramuscular injection. Olan/apiiie (Zyprexa) is also a 5HT,:D, blocker. In contrast to the above, it is sedative, produces some postural hypotension and has anticholinergic side effects. It has a minimal effect on serum prolactin and is effective in a wide range of doses -generally IO-20mg per da> arc needed. Olanzapine is wcll-tolcrated, but weight yam and metabolic side effects have proven to be problematic m a patient population that alrcad) has a higher risk of conditions such as type II diabetes and hyperlipidacmia. Careful monitoring of weight, glucose metabolism and lipid profile is essential when prescribing olanzapine. It is available in quick-release and regular tablets, as well as intramuscular injectable forms. Quetiapine(Seroqucl)hasa low affinity for D,. D,and5H I receptors, ami moderate alliniiv tot ci. and u receptors. It is more specific lo the mesolimbic area and does not raise scrum prolactin. It is a generally wcll-tolcrated drug and IS used across a wide dose range. It is available in tablet form. Dose range: mg per day. /aprasidonc(vieodon) is also a 51 IT.:!), blocker and has significant agonist actnitv at the''iii. receptors. Kliieacy is similar to haloperidol and olanzapine and it is generally well-tolerated w uh fewer metabolic problems than w ith olanzapine. I low ever, it has a moderate effect on the QT interval which may make it more likely than otheraniipsvehoticstocauscvcniriculararrhythniia.lt is available in capsule and intramuscular injectable forms. IX)se range: 40-S0mg I w ice daily for labs. HMOmg per day for intramuscular injection. Aripiprazole (Ability) is a partial agonist at D, receptors, a potent antagonist at 51 IT., receptors and a partial agonist al 51 IT,, receptors. II is well-tolerated and has a low incidence of associated l-pshs. It is not associated with symptomatic hyperprolaclinaemia. QTc prolongation, impaired glucose tolerance or substantial weight gain. Il is available in tablet form. Dose range l5-30mgday. As is the ease with the conventional antipsychotics, second-general ion drugs are often used lor sedation and restraint of aggressive or disruptive patients. Tliisshould.howcver.lv undertaken with caution arid it is generally recommended that benzodiazepines, such as lorazepam, be use*! as first-line treatment, especially if the cause of the psychosis is unknown i ;iuiion needs lo be exercised when administering parenteral olanzapine Page 5 / 5 Size=420X298mm Circulation: Readership: concomitantly with benzodiazepines, as cardiopulmonary depression and severe hypotension can arise - it is adv isablc when either has been administered to wait al least one hour before the other is administered. References available on request.