Sympathomimetics overdose

B. Do not use as single therapy for hypertension resulting from sympathomimetic overdose. Propranolol produces peripheral vascular beta-blockade, which may abolish beta-2-mediated vasodilation and allow unopposed alpha-mediated vasoconstriction, resulting in paradoxic worsening of hypertension. 

The answer is local anesthetic properties it can block the initiation or conduction of a nerve impulse. It is biotransformed by plasma esterases to inactive products. In addition, cocaine blocks the reuptake of norepinephrine. This action produces CNS stimulant effects including euphoria, excitement, and restlessness Peripherally, cocaine produces sympathomimetic effects including tachycardia and vasoconstriction. Death from acute overdose can be from respiratory depression or cardiac failure Cocaine is an ester of benzoic acid and is closely related to the structure of atropine. 

Overdose produces excessive sympathomimetic effects, including vomiting, tremor, hyperreflexia, seizures, confusion, hallucinations, and diaphoresis. 

Despite impressions to the contrary, MAOIs are generally well tolerated if patients observe the restricted diet and avoid medications that contain sympathomimetic amines. Adverse effects are rarely a treatment-limiting problem with the exception of hypotension. MAOIs also fall between TCAs and SSRIs in terms of overdose risk. Major toxic reactions to MAOIs are uncommon but require immediate discontinuation and symptomatic treatment. 

Sympathomimetic effects (from NA re-uptake inhibition) and antimuscarinic effects can cause a sinus tachycardia. Postural hypotension may occur as a result of sympatholytic al-adrenoceptor antagonism. With overdoses of these drugs, there is a reduced re-uptake of catecholamines, resulting in arrhythmias and hypertension. Tricyclic compounds have a high... 

Sympathomimetic drug overdose. A person who abuses drugs is at risk of an overdose. Symptoms... 

Sympathomimetic drug overdose. Some overdose symptoms are similar to those experienced during withdrawal. These include cramps, nightmares, nausea, and trembling. Vomiting will be more intense. The person may be dizzy and blood pressure may drop or rise. Respiration (breathing) is rapid, and the person may faint. 

Drug overdose Acute toxicity requiring emergency medical treatment is rare. When it occurs there is a typical sympathomimetic syndrome, which should be treated with fluids, control of hyperthermia, bed rest, and, if necessary, sedation with benzodiazepines (1). 

Action on receptors provides numerous examples. Beneficial interactions are sought in overdose, as with the use of naloxone for morphine overdose (opioid receptor), of atropine for anticholinesterase, i.e. insecticide poisoning (acetylcholine receptor), of isoproterelol (isoprenaline) for overdose with a P-adrenoceptor blocker (p-adrenoceptor), of phentolamine for the monoamine oxidase inhibitor-sympathomimetic interaction (a-adrenoceptor). 

Overdose of sympathomimetics is treated according to rational consideration of mode and site of action (see Adrenaline, below). 

Treatment for sympathomimetic amine overdose involves general supportive measures. Acid diuresis wiU enhance the elimination of the amphetamines, but its use is con-troversiaT and is certainly not without the risk of renal failure from precipitation of myoglobin (enhanced at acid pH) in renal tubules (myoglobinuria is the result of rhabdomyolysis). 

Methylphenidate (Ritalin). Ritalin is a sympathomimetic agent with psychostimulant properties similar to S(+)-amphetamine. It is widely used to treat attention deficit hyperactivity disorder (ADHD) in children and adults. There has been increasing diversion and abuse of methylphenidate among children and adults for its stimulant and purported aphrodisiac properties. In overdose, the clinical effects of methylphenidate are similar to those of amphetamine. Relatively few cases of serious overdose have been reported. 

Accidental local infiltration of potent alpha agonists such as norepinephrine may lead to tissue ischemia and necrosis if not promptly reversed infiltration of the ischemic area with phentolamine is sometimes used to prevent tissue damage. Overdose with drugs of abuse such as amphetamine, cocaine, or phenylpropanolamine may lead to severe hypertension because of their indirect sympathomimetic actions. This hypertension will usually respond well to alpha-blockers. Sudden cessation of clonidine therapy leads to rebound hypertension (Chapter 11) this phenomenon is often treated with phentolamine. 

Hyperkalemia usually exacerbates the cardiac toxicity of class I drugs. Treatment of overdose with these agents is often carried out with sodium lactate (to reverse drug-induced arrhjThmiasj and pressor sympathomimetics (to reverse drug-induced hypotension) if indicated. 

B. Toxicodynamics Toxicodynamics is a term used to denote the injurious effects of toxins, ie, their pharmacodynamics. A knowledge of toxicodynamics can be useful in the diagnosis and management of poisoning. For example, hypertension and tachycardia are typically seen in overdoses with amphetamines, cocaine, and antimuscarinic drugs. Hypotension with bradycardia occurs with overdoses of calcium channel blockers, beta-blockers, and sedative-hypnotics. Hypotension with tachycardia occurs with tricyclic antidepressants, phenothiazines, and theophylline. Hyperthermia is most frequently a result of overdose of drugs with antimuscarinic actions, the salicylates, or sympathomimetics. Hypothermia is more likely to occur with toxic doses of ethanol and other CNS depressants. Increased respiratory rate is often a feature of... 

Aspirin, sympathomimetics, agents with muscarinic blocking actions, and drugs that cause muscle rigidity or seizures are all likely to cause hyperthermia at toxic doses. Hypothermia is more typical of overdoses with opioids or sedative-hypnotics. The answer is (C). 

A a X 0 Q, 1 W s o a (D CQ PO/PR. Well absorbed, liver metabolism, kidney excretion. Dozens of standard and long-acting preparations available. Patients with seizure disorder, cardiovascular disorder or peptic ulcer disease. Sympathomimetics T risk of heart and CNS toxicity. Cimetidine, oral contraceptives and several antibiotics t half-life of theophylline - thus T toxicity. Phenobarbital and phenytoin induce metabolism of theophylline, thus i half-life. Dehdydration results from t diuresis with concurrent use of furosemide. Warn patients doubling a dose, even if one is missed, is very dangerous. Intoxication may cause seizures. Treat overdose with ipecac, activated charcoal, and a cathartic. 

The toxicity of ephedrine is closely related to adverse cardiovascular events, since the clinical presentation of toxicity reflects the sympathomimetic activity of these agents. The adrenergic effects can shorten cardiac refractory periods, permitting the development of reentrant cardiac arrhythmias. The worst complication related to the use of ephedrine is thrombotic stroke, presumably resulting from vasoconstriction of large cerebral arteries that in turn leads to local thrombosis [71]. Other adverse effects include hypertension, diaphoresis, hypothermia, and agitation. The best treatment in an overdose is the rapid identification of the symptoms followed by supportive management. 

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