VASSOPRESSORS USED IN SHOCK- includes-

Inotropic effects - Isoproternol, Dobutamine, Dopamine, Ephinephrine,

Mixed effects- Norephinephrine, Ephedrine, Mephentermine

Pressors effects- Metaraminol Methoxamine Phenylephrine

Interacting drugs - summary-

 + Dobutamine-

 Bretylium     -    Bretylium potentiate the action of vasopressors on adrenergic receptors resulting arrhythmias

 Guanethidine     -     Guanethedine increase pressor response of direct acting vasopressors resulting in severe hypertension

 Halogenated hydrocarbon anesthestics    -     Halogenated hydrocarbon anesthestics sensitise the myocardium hydrocarbon to effects of catecholamines. Use of vasopressors may lead to serious arrthymias. Use with extreme caution

Oxytoxic drugs     -     in obstertics, vasopressor drugs used to correct hypotension or if added to local anesthetic soln. oxytoic drugs cause severe persistent hypertension.

 Tricyclic  antidepressants    -    pressor response of direct acting vasopressors potentiated by tricyclic antidepressants. Use with caution

VASSOPRESSORS USED IN SHOCK- includes-

Inotropic effects - Isoproternol, Dobutamine, Dopamine, Ephinephrine,

Mixed effects- Norephinephrine, Ephedrine, Mephentermine

Pressors effects- Metaraminol Methoxamine Phenylephrine

Cardiovascular-

Increased heart rate, blood pressure and ventricular ectopic activity, hypotension, premature ventricular beats

Reactions at injection site-

Phlebitis has occurred occassionally and local inflammatory exhanges have ocurred following inadvertant infiltration.

Miscellaneous- (uncommon)

Nausea, headache, anginal pain, nonspecific chest pain, palpitations, shortness of breath, fever

Hypersensitivity,cardiac arrhythmias,constritive pericarditis.

Special precautions:

Aortic stenosis,mitral stenosis,pregnancy.Safety in children and infants not established. Monitoring-

Continously monitor ECG and blood pressure. Monitor pulmonary wedge pressure and cardiac output whenever possible.

Hypovalemia- use is not substitute for the replacement of blood,plasma, fluids and electrolyte, which should be restored promptly when loss has occured.

Correct hypovalemia with suitable volume expanders before treatment is instituted. Ineffective- in the presence of marked mechnaical obstruction such as severe valvular aortic stenosis.

Usage following acute myocardial infarction- any agent which increases contratile force and heart rate may increase the size of an infarction by intensifying ischemia.

Sulfite sensitivity- some of these products contain sulfites that may cause allergic type reactions including anaphylactic symptoms and life threatening or less severe asthmatic episodes in certain susceptible individuals.

Warnings-

Increase in heart rate or blood pressure- patients with preexisting hypertension appear to face an increased risk of developing an exaggerated pressor response.

Hypotension- precipitous decreases in blood pressure have occassionally been described in association with dobutamine therapy. Decreasing the dose or discontinuation the infusion typically results in rapid return of blood pressure to baseline values.

Etopic activity- dobutamine may precipitate or exacerbate ectopic activity,but it rarely has caused ventricular tachycardia.

Hypersentivity- reactions including skin rash,pruritus of the scalp, fever, eosinophilia and bronchospasm may occur occassionally with dobutamine

Pregnancy- use only when clearly needed and when the potential benefits outweigh the potential hazards to the fetus.

Children- safety and efficacy for use in children have not been established.

Date of Approval     1993

Dosage:

Rate of infusion usually ranges from 2.5mcg to 10mcg/kg/min.Rare cases 40mcg/kg/min have been required.

Overdosage-

Symptoms

Excessive alteration of blood pressure, anorexia, nausea,vomiting,tremor, anxiety, palpitations headache, shortness of breath, anginal and non specific chest pain, myocardial ischemia, ventricular fibrillation or tachycardia.

Treatment

1.Reduce rate of administration or temporarily and discontinue until condition satbilizes

2. Establish an airway and ensure oxygenation and ventilation

3. Initiate resuscitative measures promptly.

4. Severe ventricular tachyarrhythmias may be successfully treated with propranol or lidocaine

Missed dose-

 1. If you miss a dose of this medicine, and remember within 6 hours of take it as soon as possible unless the dose is less than 4 hours.

2. However, if you do not remember until later, skip the missed dose and go back to your regular dosing schedule.

3. Do not double doses.

Pharmacology:

Dobutamine is chemically related to dopamine. Its primary activity results from stimulation of alpha, beta,receptors of the heart while producing comparitively mild chronotropic, hypertensive ,arrhythmogenic and vasodilative effects.

Pharmacokinetics:

The plasma half-life of dobutamine is two minutes. In urine the major excretion products are the conjugates of dobutamine and the inactive 3-o-methyl dobutamine.

Reports not availalble.

Pregnancy:

Dobutamine has not been administered to pregnant women; use only when clearly needed. and when the potential benefits outweigh the potential

Children- Safety and efficacy for use in children have not been established.