DOBUTAMINE

Dobutamine is administered by continuous intravenous infusion due to the short half life of dobutamine. 45% Sodium Chloride Intravenous Infusion BP Sodium Lactate Intravenous Infusion BP 20ml Dobutamine Sterile Concentrate will yield the following concentrations when diluted: In 250ml: 1000 micrograms/ml of dobutamine In 500ml: 500 micrograms/ml of dobutamine In 50ml: 5,000 micrograms/ml (only appropriate in patients on restricted fluid intake, for administration by infusion pump for accuracy of dosing).

The prepared solution should be used within 24 hours. After dilution, dobutamine should be administered intravenously through an, intravenous needle or catheter. An iv drip chamber or other suitable metering device is essential for controlling the rate of flow in drops per minute.

5 to 10 micrograms per kg body weight per minute,m according to the patient's heart rate, blood pressure, urine output, and if available cardiac output. 5 up to 40 micrograms per kg body weight per minute have been used. It is recommended that treatment with dobutamine should be discontinued gradually.

Paediatric population For all paediatric age groups (neonates to 18 years) an initial dose of 5 micrograms/kg/minute, adjusted according to clinical response to 2–20 micrograms/kg/minute is recommended. 0 micrograms/kg/minute will produce a response.

There is reason to believe that the minimum effective dosage for children is higher than for adults. Caution should be taken in applying high doses, because there is also a reason to believe that the maximum tolerated dosage for children is lower than the one for adults.

5 micrograms/kg/minute, but reducing or termination of the rate of dobutamine infusion is all that is required for rapid reversal of undesirable effects. A great variability has been noted between paediatric patients in regard to both the plasma concentration necessary to initiate a hemodynamic response (threshold) and the rate of hemodynamic response to increasing plasma concentrations, which demonstrates that the required dose for children cannot be determined a priori and should be titrated in order to allow for the supposedly smaller “therapeutic width” in children.

9%. Infuse higher concentration solutions through central venous catheter only. Dobutamine intravenous infusion is incompatible with bicarbonate and other strong alkaline solutions.

Effects on the cardiovascular system are complex. Stimulation of alpha- adrenergic receptors produces vasoconstriction with resultant hypertension. Dobutamine may cause a marked increase in heart rate or blood pressure. Hypertensive patients can develop marked systolic hypertension.

The rise in blood pressure may produce cerebral haemorrhage and pulmonary oedema. There may also be a reflex bradycardia but stimulation of β1-adrenergic receptors of the heart may cause tachycardia, palpitations, ectopic heart beats and cardiac arrhythmias, anginal pain and cardiac arrest.

Because dobutamine facilitates atrioventricular conduction, patients with atrial fibrillation may be at risk of developing a rapid ventricular response. If rapid ventricular rates occur in the presence of obstructive coronary artery disease, myocardial ischaemia may be induced or exacerbated.

Occasionally hypotension with dizziness and fainting and flushing may occur due to vasodilation, and, as with other catecholamines, serum potassium could be reduced. Other side effects include nausea, vomiting, headache, anxiety, paraesthesias, non-specific chest pain, eosinophilic myocarditis, shortness of breath, myocardial infarction, coronary artery spasm and reactions suggestive of hypersensitivity including rash, fever, eosinophilia, bronchospasm and local cellulitis at the site of infusion.

Pruritus of the scalp has been reported. Extravasation of parenterally administered catecholamines may result in tissue necrosis and sloughing. Phlebitis has occasionally been reported at the site of infusion. Partial tolerance may develop with infusions over more than 72 hours, requiring dosage increase.

There is the potential for psychosis to occur as a rare side effect of dobutamine. There is also the potential for urinary urgency to occur during infusion of relatively high doses (15 micrograms/kg/minute) of dobutamine. 4) Paediatric population The undesirable effects include elevation of systolic blood pressure, systemic hypertension or hypotension, tachycardia, headache, and elevation of pulmonary wedge pressure leading to pulmonary congestion and edema and symptomatic complaints.

In general, sympathomimetic agents should be used with caution in patients who may be particularly susceptible to their effects, particularly those with hyperthyroidism. Great care is also needed in patients with cardiovascular disease such as ischaemic heart disease, acute heart failure, arrhythmia or tachycardia, occlusive vascular disorders including arteriosclerosis, hypertension or aneurysms.

Anginal pain may be precipitated in patients with ischaemic heart disease, particularly after myocardial infarction. Care is also required when sympathomimetic agents are given to patients with diabetes mellitus or closed angle glaucoma.

Avoid the use of sympathomimetic agents in patients with phaeochromocytoma. In particular, dobutamine should be avoided or used only with great caution in patients with marked obstruction of cardiac ejection, such as idiopathic hypertrophic subaortic stenosis.

It may exacerbate pre-existing tachycardia and hypertension. Metabolic acidosis, hypoxia, hypercapnia and hypovolaemia should be corrected before and during dobutamine treatment. Use with caution in cardiogenic shock complicated by severe hypotension.

If an undue increase in heart rate or systolic blood pressure occurs during administration of dobutamine, or an arrhythmia is precipitated, the dose should be reduced or interrupted. 8). The administration of dobutamine for stress echocardiography should be only undertaken by a physician experienced with the procedure.

The physician should be vigilant during the test and the recovery period and be prepared for appropriate therapeutic intervention during the test. In the event of stress cardiomyopathy (Takotsubo syndrome) dobutamine should be stopped immediately.

Special care should be taken with the use of dobutamine in the elderly. Tolerance may occur with continuous infusions of dobutamine over more than 72 hours. Paediatric population Dobutamine has been administered to children with low-output hypoperfusion states resulting from decompensated heart failure, cardiac surgery, and cardiogenic and septic shock.

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