Dopamine

12.1 Mechanism of Action Dopamine is a natural catecholamine formed by the decarboxylation of 3,4-dihydroxyphenylalanine (DOPA). It is a precursor to norepinephrine in noradrenergic nerves and is also a neurotransmitter in certain areas of the central nervous system, especially in the nigrostriatal tract, and in a few peripheral sympathetic nerves. Dopamine elicits its pharmacological action by activating dopamine D1 and D2 receptors, beta-1 receptors and alpha-1 receptors. The activation of different receptors leading to its effects are dependent on dopamine dose.

1 INDICATIONS AND USAGE Dopamine Hydrochloride in Dextrose Injection is indicated to improve hemodynamic status in patients in distributive shock, or shock due to reduced cardiac output. Dopamine HCl in Dextrose Injection is a catecholamine indicated to improve hemodynamic status in patients in shock. ( 1 )

2 DOSAGE AND ADMINISTRATION • Correct hypovolemia, acidosis, and hypoxia prior to use. ( 2.1 ) • Administer in a large vein with an infusion pump preferably in an intensive care setting. ( 2.1 ) • Recommended starting dosage in adults and pediatric patients is 2 to 5 mcg/kg/minute as a continuous intravenous infusion. Titrate in 5 to 10 mcg/kg/minute increments based on hemodynamic response and tolerability, up to not more than 50 mcg/kg/minute. ( 2.2 ) • See the Full Prescribing Information for important preparation instructions and drug incompatibilities. ( 2.3 ) 2.1 Administration Instructions Correct Hypovolemia, Acidosis, and Hypoxia Address hypovolemia, acidosis, and hypoxia before initiating Dopamine HCl in Dextrose Injection. If patient does not respond to therapy, suspect occult hypovolemia. Acidosis may reduce the effectiveness of dopamine [see Warnings and Precautions (5.1) ] . Administration Dopamine HCl in Dextrose Injection is a premixed infusion solution that does not require dilution prior to intravenous administration. Administer Dopamine HCl in Dextrose Injection into a large vein [see Warnings and Precautions (5.1) ] with the use of an infusion pump preferably in an intensive care setting. Remove outer wrap (moisture and oxygen barrier) only when ready to administer the product. Discard product if outer wrap is damaged (e.g., tears or holes). Inspect Dopamine HCl in Dextrose Injection for particulate matter and discoloration prior to administration (the solution is clear to slightly yellow). Do not administer if the solution is darker than slightly yellow or the container is damaged. Use higher concentration premixed solutions (e.g., 3,200 mcg/mL or 1,600 mcg/mL strengths) in patients requiring fluid restriction. Discontinuation When discontinuing Dopamine HCl in Dextrose Injection, gradually reduce the infusion rate while expanding blood volume with intravenous fluids [see Warnings and Precautions (5.3) ]. 2.2 Recommended Dosage The recommended starting dosage in adults and pediatric patients is 2 to 5 mcg/kg/minute as a continuous intravenous infusion [see Dosage and Administration (2.3) ] . Titrate the infusion rate in 5 to 10 mcg/kg/minute increments based on hemodynamic response and tolerability, up to but not more than 50 mcg/kg/minute. Infusion rates may be calculated using the following formula: Infusion Rate (mL/hour) = [Dose (mcg/kg/minute) × Weight (kg) × 60 (minutes/hour)] Concentration (mcg/mL) Example calculations for infusion rates are as follows: Example 1: for a 60 kg person at the recommended initial dose of 2 mcg/kg/minute using a 1,600 mcg/mL concentration, the infusion rate would be as follows: Infusion Rate (mL/hour) = [2 (mcg/kg/minute) × 60 (kg) × 60 (minutes/hour) ] = 4.5 (mL/hour) 1,600 (mcg/mL) Example 2: for a 70 kg person at a dose of 5 mcg/kg/minute using a 3,200 mcg/mL concentration, the infusion rate would be as follows: Infusion Rate (mL/hour) = [5 (mcg/kg/minute) × 70 (kg) × 60 (minutes/hour) ] = 6.56 (mL/hour) 3,200 (mcg/mL) 2.3 Drug Incompatibilities Dopamine HCl in Dextrose Injection is incompatible with the following products; therefore, avoid simultaneous administration (through the same infusion set): • Sodium bicarbonate or other alkalinizing substances, because dopamine is inactivated in alkaline solution. • Blood, because of the risk of pseudoagglutination of red cells • Iron salts Do not add additional medications in the premixed infusion solution.

6 ADVERSE REACTIONS The following adverse reactions are described elsewhere in the labeling: • Tissue Ischemia [see Warnings and Precautions (5.1) ] • Cardiac Arrhythmias [see Warnings and Precautions (5.2) ] • Hypotension [see Warnings and Precautions (5.3) ] • Severe Hypersensitivity Reactions [see Warnings and Precautions (5.4) ] The following adverse reactions have been identified during post-approval use of dopamine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Cardiac Disorders : anginal pain, palpitation Gastrointestinal Disorders : nausea, vomiting Metabolism and Nutrition Disorders : azotemia Nervous System Disorders : headache, anxiety Respiratory Disorders : dyspnea Skin and Subcutaneous Tissue Disorders : piloerection Vascular Disorders : hypertension The most common adverse reaction is localized vasoconstriction due to extravasation. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer, Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

7 DRUG INTERACTIONS See Table 1 for clinically significant drug interactions with dopamine. Table 1: Clinically Significant Drug Interactions with Dopamine Halogenated Anesthetics Clinical Impact: Concomitant use may increase cardiac autonomic irritability and can sensitize the myocardium to the action of dopamine which may lead to ventricular arrhythmias and hypertension. Intervention: Monitor cardiac rhythm. Examples: desflurane, enflurane, isoflurane, and sevoflurane. MAO Inhibitors Clinical Impact: Because dopamine is metabolized by monoamine oxidase (MAO), inhibition of this enzyme prolongs and potentiates the effect of dopamine which may result in severe hypertension and cardiac arrhythmia. Intervention: Reduce the recommended starting dosage to no greater than one-tenth (1/10) of the recommended dose in patients who have been treated with MAO inhibitors within two to three weeks prior to the administration of Dopamine HCl in Dextrose Injection. Examples: isocarboxazid, phenelzine, tranylcypromine, rasagiline, selegiline, linezolid. Tricyclic Antidepressants Clinical Impact: Concomitant use may potentiate the cardiovascular effects of dopamine (e.g., hypertension). Intervention: Monitor blood pressure. Examples: amitriptyline, desipramine, doxepin, imipramine, nortriptyline. Vasopressors Clinical Impact: Concomitant use may result in severe hypertension. Intervention: Monitor blood pressure. Examples: norepinephrine, epinephrine, oxytocin. • Halogenated anesthetics : Can sensitize the myocardium to the effects of dopamine and can produce ventricular arrhythmias and hypertension. ( 7 ) • MAO inhibitors : Risk of severe hypertension. Reduce recommended Dopamine HCl in Dextrose Injection dosage. ( 7 ) • Tricyclic antidepressants : Risk of hypertension. Monitor blood pressure. ( 7 ) • Vasopressors : Risk of severe hypertension. Monitor blood pressure. ( 7 )