Dopamine hydrochloride is the synthetic form of endogenous catecholamine, a hormone released in times of physical or emotional stress. It is also an inotropic vasopressor agent that has effects on the heart muscle contraction and on blood pressure. In addition, it induces vasodilatation of the renal blood vessels and is indicated in cases of trauma, systemic infection, or sepsis, open heart surgery, renal failure and in shock syndrome due to myocardial infarctions.
Effects on the Heart
Since dopamine has a direct effect on the myocardium, it increases the heart rate, cardiac contractility and enhanced impulse conduction. This takes place because of a direct action on certain receptors, beta-adrenoceptors, and by an indirect action through the release of norepinephrine, same as noradrenaline, from storage in certain nerve endings. It generally takes an intermediate dosage provoke these effects. Once injected, the action starts within five minutes. Due to its short half-life, the action lasts less than 10 minutes.
Adverse Reactions
Potential adverse reactions include ventricular arrhythmia, irregular contractions in one chamber of the heart, ectopic beats, a heart sound that is not synchronized with the regular rhythm, tachycardia and angina, or severe chest pain. Additional potential adverse reactions include palpitation, cardiac conduction abnormalities that can be seen in a EKG, bradycardia, opposite of tachycardia, hypotension, hypertension and vasoconstriction, sustained contraction of the blood vessels. Although these potential adverse reactions are not common, it is not possible to accurately state the frequency with which these adverse reactions typically occur.
Precautions
This drug should not be used in patients with a tumor in the adrenal glands called pheochromocytoma. It shouldn't be administered if abnormalities in the electric conduction of the heart have not been corrected. If a patient has received a type of antidepressant known as an MAO, or monoamine oxidase inhibitor, within 2 to 3 weeks prior to the administration of dopamine, the dopamine can trigger an adverse reaction. Tricyclic antidepressants can also potentiate the action of this agent. The urine flow may increase considerably if dopamine is taken simultaneously with diuretics.
Other considerations
Agents, such as propranolol and metoprolol, can stop the cardiac effects of dopamine. You can also manage the effects in the peripheral blood vessels caused by high doses of dopamine hydrochloride with alpha-blockers such as prazosin. You should not administer the anticonvulsant phenytoin at the same time as dopamine because it can cause hypotension and bradycardia, compromising the integrity of the heart and brain.
