Cardiovascular drugs atropine

B. Phenylephrine is an aj-selective agonist. It causes an increase in peripheral vascular resistance. The major cardiovascular response to this drug is a rise in blood pressure associated with reflex bradycardia. The slowing of the heart rate is blocked by atropine. 

For many drugs, at least part of the toxic effect may be different from the therapeutic action. For example, intoxication with drugs that have atropine-like effects (eg, tricyclic antidepressants) reduces sweating, making it more difficult to dissipate heat. In tricyclic antidepressant intoxication, there may also be increased muscular activity or seizures the body s production of heat is thus enhanced, and lethal hyperpyrexia may result. Overdoses of drugs that depress the cardiovascular system, eg, 13 blockers or calcium channel blockers, can profoundly alter not only cardiac function but all functions that are dependent on blood flow. These include renal and hepatic elimination of the toxin and any other drugs that may be given. 

Actions Meperidine causes a depression of respiration similar to that of morphine, but there is no significant cardiovascular action when the drug is given orally. On intravenous (IV) administration, meperidine produces a decrease in peripheral resistance and an increase in peripheral blood flow, and may cause an increase in cardiac rate. As with morphine, meperidine dilates cerebral vessels, increases cerebrospinal fluid pressure, and contracts smooth muscle (the latter to a lesser extent than does morphine). In the gastrointestinal tract, meperidine impedes motility, and chronic use results in constipation. Meperidine does not cause pinpoint pupils, but rather causes the pupils to dilate because of an atropine-like activity. 

MODIFICATION OF THE METHOD Clutton et al. (1992) studied the autonomic and cardiovascular effects of neuromuscular blockade antagonism in the dog. Neuromuscular blockade was antagonized with various anticholinesterase-antimuscarinic drug combinations including atropine, neostigmine and glycopyrrolate. 

Tests of Cardiovascular Status. Pulse strength, regularity, heart rate, and blood pressure measurements should be evaluated. Some topically administered ocular drugs, such as atropine and p-blockers, can affect systemic blood pressure and cardiac activity. This is especially important before and during long-term treatment with P-blockers in those patients with glaucoma. 

Atropine sulfate is the drug of choice. Epinephrin may assist in overcoming severe cardiovascular or bronchoconstriction. Diazepam, phenytoin, and phe-nobarbital may be given in cases of seizures. Induction of emesis is not necessary due to spontaneous vomiting. Activated charcoal slurry with or without... 

Muscarinic agonists are administered subcutaneously to achieve an acute response and orally to treat more chronic conditions. Should serious toxic reactions to these drugs arise, atropine sulfate (0.5—1 mg in adults) should be given subcutaneously or intravenously. Epinephrine (0.3—1 mg, subcutaneously or intramuscularly) also is of value in overcoming severe cardiovascular or bron-choconstrictor responses. 

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