The tricyclic antidepressant which is most lethal on overdose is:
A. Dosulepin or dothiepin together with amitriptyline has been associated with most cases of fatal tricyclic antidepressant overdose. The ingestion of large quantities of tricyclics in overdose results in complex changes in the normal pharmacokinetics observed at therapeutic doses. Due to anticholinergic effects, gastric emptying is delayed and a sustained slow absorption takes place. Respiratory depression produces acidosis, which reduces protein binding and increases the active free fraction of the toxic drug.The toxic effects of tricyclics are due mainly to an increased sympathetic drive, adrenergic blockade, arrythmogenic effect on myocardium, and anticholinergic action.
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A patient develops neuroleptic malignant syndrome secondary to antipsychotic prescription.
Which one of the following properties of antipsychotics predicts a lower risk of producing neuroleptic malignant syndrome?
A. Many treatment variables are associated as risk factors for neuroleptic malignant syndrome (NMS). Nearly all dopamine antagonists have been associated with NMS, although high-potency conventional antipsychotics are associated with a greater risk compared with low potency agents and atypical antipsychotics. Intramuscular administration, rapid tranquilization, and faster titration rates are associated with higher incidence. Drugs with an intrinsic anticholinergic property have a lower propensity to cause NMS. Atypical agents produce atypical NMS, where the classic rigidity or hyperthermia component of NMS may be conspicuously absent. The risk of NMS is not related to α adrenergic blockade or sedative property of an antipsychotic drug.
Which one of the following agents produces dysphoria, myoclonus, flu-like symptoms, ataxia, hyperacusis, and anxiety on withdrawal?
B. Benzodiazepine withdrawal symptoms include anxiety, inner tension, dizziness, insomnia, and anorexia. More severe withdrawal symptoms include nausea and vomiting, severe tremor, muscle weakness, postural hypotension, and tachycardia with psychological symptoms of dysphoria, depressive pessimistic thoughts, and obsessive ruminations. Myoclonus, pain symptoms, ataxia, kinaesthetic hallucinations, depersonalization, and hyperacusis are also noted. The withdrawal symptoms can develop after only 4 weeks of continuous use. Clonazepam, carbamazepine, and long-acting benzodiazepines themselves have been used in the management of withdrawal symptoms.
Among antipsychotic agents, a high anticholinergic effect is noted for which one of the following pairs?
B. Typical neuroleptics vary in their potential to cause anticholinergic symptoms. As a general rule, high-potency medications such as haloperidol produce less anticholinergic effects compared to low-potency drugs such as chlorpromazine and thioridazine. Peripheral anticholinergic effects include dry mouth, blurred vision, constipation, and urinary retention. Central anticholinergic effects, such as confusion and delirium, are seen especially in overdose of low-potency agents and in the elderly.
Severe perspiration unrelated to ambient temperature is a side-effect associated with the prescription of:
D. Severe sweating incongruent to room temperature is associated with TCAs, SSRIs, and venlafaxine. This is a socially disabling side-effect. Drugs such as terazosin, cyproheptadine, benztropine, and oxybutynin have been tried anecdotally to treat this symptom but none of these has been recommended for routine use. The mechanism by which SSRIs increase sweating is unknown but is hypothesized to be through activation of the sympathetic nervous system or by action on the hypothalamus.
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