Name of the Inotropic sympathomimetics drugs:
- Adrenaline
- Dopamine
- Dobutamine
- Isoprenaline
Mechanism of Action:
- Actions vary depending on which receptors are stimulated.
- Mimic effect of endogenous catecholamines- norepinephrine& epinephrine.
- Activates sympathetic nervous system which in turn turns on the fight or flight response.
- Adrenaline acts on a peripheral vasculature and adrenoceptors (myocardium), producing positive inotropic and chronotropic effects.
- Low- dose dopamine and dobutamine stimulates beta 1 adrenoceptors in the myocardium, predominantly increasing contractility.
Stimulates 2 types of adrenergic receptors ( α & β )
- α : – Vasoconstriction
- β -1 receptors – increases HR & Contractility
- β -2 receptors: – Vasodilation & Bronchodilation
Indications:
- Cardiac decompensation
- Shock
- Anaphylaxis
- Bronchospasm
- Bradycardia
- Post- Cardiac Arrest
| Adrenaline |
| Availability: Injection, Solution (Prefilled Syringes): 0.3 mg/0.3 mL, 0.15 mg/0.3 mL, 0.15 mg/0.15 mL. Injection, Solution: 0.1 mg/ mL (1:10,000), 1 mg/mL (1:1,000). Solution for Oral Inhalation: (Adrenalin): 2.25% (0.5 mL). |
| Administration/handling: IV Reconstitution • For injection, dilute each 1 mg of 1:1,000 solution with 10 mL 0.9% NaCl to provide 1:10,000 solution and inject each 1 mg or fraction thereof over 1 min or more (except in cardiac arrest). • For infusion, further dilute with 250–500 mL D5W. Maximum concentration 64 mcg/mL. Rate of administration • For IV infusion, give at 1–10 mcg/min (titrate to desired response). Storage: Store parenteral forms at room temperature. • Do not use if solution appears discolored or contains a precipitate. |
| SQ: Shake ampule thoroughly. • Use tuberculin syringe for injection into lateral deltoid region. • Massage injection site (minimizes vasoconstriction effect). Use only 1:1,000 solution. |
| Nebulizer: No more than 10 drops Adrenalin Chloride solution 1:100 should be placed in reservoir of nebulizer. • Place nozzle just inside pt’s partially opened mouth. • As bulb is squeezed once or twice, instruct pt to inhale deeply, drawing vaporized solution into lungs. • Rinse mouth with water immediately after inhalation (prevents mouth/ throat dryness). • When nebulizer is not in use, replace stopper, keep in upright position |
| Anaphylaxis IM, SQ: Adults, elderly: 0.2–0.5 mg (0.2–0.5 mL of 1:1,000 solution). May repeat q5–15 min if anaphylaxis persists. Children: 0.01 mg/kg (0.01 mL/kg of a 1:1,000 solution) q5–15 min. Maximum: 0.3–0.5 mg q5–15 min. |
| Hypotension (Shock) IV infusion: Adults, elderly: Initially, 0.1-0.5 mcg/kg/min. Titrate to desired response. |
| Cardiac Arrest: IV: Adults, elderly: Initially, 1 mg. May repeat q3–5min as needed. Children: Initially, 0.01 mg/kg (0.1 mL/ kg of a 1:10,000 solution). May repeat q3–5min as needed. |
| Endotracheal: Adults, elderly: 2–2.5 mg q3–5 min as needed. Children: 0.1 mg/kg (0.1 mL/kg of a 1:1,000 solution). May repeat q3–5min as needed. Maximum single dose: 2.5 mg. |
| Dopamine |
| Availability: Injection Solution: 40 mg/mL, 80 mg/ mL, 160 mg/mL. Injection (Premix with Dextrose): 0.8 mg/mL (250 mL, 500 mL), 1.6 mg/mL (250 mL, 500 mL), 3.2 mg/mL (250 mL). |
| Administration/handling: Fluid volume depletion must be corrected before administering Dopamine (may be used concurrently with fluid replacement). IV Reconstitution: Available prediluted in 250 or 500 mL D5W or dilute in 250–500 mL 0.9% NaCl or D5W, to maximum concentration of 3,200 mcg/mL (3.2 mg/mL). Rate of administration: Administer into large vein (antecubital fossa, central line preferred) to prevent extravasation. Use infusion pump to control flow rate. • Titrate drug to desired hemodynamic, renal response (optimum urinary flow determines dosage). Storage • Do not use solutions darker than slightly yellow or discolored to yellow, brown, pink to purple (indicates decomposition of drug). • Stable for 24 hrs after dilution. |
| Effects of Dopamine are dose dependent. Titrate to desired response. Doses greater than 20 mcg/kg/min may not have beneficial effect on BP and may increase risk of tachyarrhythmias. |
| Hemodynamic Support IV infusion: Adults, elderly, children: Range: 2–20 mcg/kg/min. Titrate to desired response. May gradually increase by 5–10 mcg/kg/min increments. Maximum: 50 mcg/kg/min. Neonates: 2–20 mcg/kg/min. Titrate gradually by 5–10 mcg/kg/min to desired response. |
| Dobutamine |
| Availability: Infusion (Ready-to-Use): 1 mg/mL (250 mL), 2 mg/mL (250 mL), 4 mg/mL (250 mL). Injection Solution: 12.5-mg/mL vial. |
| Administration/handling: Correct hypovolemia with volume expanders before Dobutamine infusion. Pts with atrial fibrillation should be digitalized before infusion. Administer by IV infusion only. IV Reconstitution: Dilute vial in 0.9% NaCl or D5W to maximum concentration of 5,000 mcg/mL (5 mg/mL). Rate of administration: Use infusion pump to control flow rate. • Titrate dosage to individual response. • Infiltration causes local inflammatory changes. • Extravasation may cause dermal necrosis. Storage: Store at room temperature. • Pink discoloration of solution (due to oxidation) does not indicate significant loss of potency if used within recommended time period. • Further diluted solution for infusion is stable for 48 hrs at room temperature, 7 days if refrigerated. |
| Cardiac Decompensation (Hemodynamic Support) IV infusion: Adults, elderly: Initially, 0.5–2.5 mcg/kg/min. Maintenance: 2–20 mcg/kg/min titrated to desired response. May be infused at a rate of up to 40 mcg/kg/min to increase cardiac output. Neonates, infants, children, adolescents: Initially, 0.5–1 mcg/ kg/min. Titrate gradually every few minutes until desired response. Usual Range: 2–20 mcg/kg/minute. |
| Isoprenaline/ isoproterenol |
| Availability: injectable solution: 0.2mg/mL |
| Administration/ handling: IV/IM Administration: Administer by IV infusion (requires infusion pump), or by direct IV, IM, or SC injection. In extreme emergencies, by intracardiac injection. |
| IV Preparation: 1 mg (5 mL) in 500 mL D5W (2 mcg/mL) for IV infusion Storage: Store in a cool place between 2-15°C. Protect from light. |
| Adams-Stokes Attacks, Cardiac Arrest, or Heart Block IV bolus: 0.02-0.06 mg (1-3 mL of a 1:50,000 dilution), initially, THEN doses of 0.01-0.2 mg IV infusion: 5 mcg/min (1.25 mL of a 1:250,000 dilution), initially, THEN doses of 2-20 mcg/min based on patient’s response. |
| Shock: 0.5-5 mcg/min (0.25-2.5 mL of a 1:250,000 dilution) IV infusion. |
| Bronchospasm During Anaesthesia: 0.01-0.02 mg IV repeat PRN |
Cautions and contra-Indications:
- Closed angle glaucoma (adrenaline)
- Pheochromocytoma (dopamine).
- Atrial and Ventricular tachyarrhythmias (dobutamine).
- Use with caution in patients with recent use of MAOIs. (within 2-3 weeks)
Side-Effects:
- GI disturbances
- Hypotension/Hypertension.
- Peripheral vasoconstriction – necrosis, sloughing & gangrene.
- Tachycardia.
- Arrhythmias
Metabolism And Half-Life:
Metabolized by the liver, kidney or plasma MAO and COMT: t ½ 2min.
Drug Interactions:
- Adrenaline should not be used with other sympathomimetic agents due to the additive effect.
- Hypertensive crisis when given in combination with MAOIs.
- Hypertension and reflex bradycardia when given in combination with beta- blockers.
Important points:
- In patient with septic or haemorrhagic shock, the volume must be replaced (though this may worsen cardiogenic shock), after which sympathomimetics may be required to improve cardiac output.
- Often used in the intensive care setting to maintain perfusion to vital organs.
- Adrenaline is used as part of resuscitation council UK guidelines.
NURSING CONSIDERATIONS
Baseline assessment
- Obtain initial B/P, heart rate, respirations. Determine weight (for dosage calculation).
- Pt must be on continuous cardiac monitoring.
- Assess ECG, B/P continuously (be alert to precipitous B/P drop).
- Assess patency of IV access.
- Correct hypovolemia before drug therapy.
- Be alert to patient complaint of headache.
Intervention/evaluation:
- Monitor IV flow rate diligently. Assess for extravasation characterized by blanching of skin over vein, coolness (results from local vasoconstriction); color, temperature of IV site extremity (pallor, cyanosis, mottling).
- Assess peripheral circulation (palpate pulses, note color/temperature of extremities). Assess nailbed capillary refill.
- Continuously monitor for cardiac arrhythmias.
- Monitor changes of B/P, HR. (hypertension risk greater in pts with preexisting hypertension).
- Check cardiac output, pulmonary wedge pressure/central venous pressure (CVP) frequently.
- Assess lung sounds for rhonchi, wheezing, rales.
- Monitor ABGs. In cardiac arrest, adhere to ACLS protocols.
- Maintain accurate I&O; measure urinary output frequently. Report urine output less than 30 mL/hr.
- Immediately notify physician of cardiac arrhythmias, significant increase in B/P, heart rate, decreased urinary output, decreased peripheral circulation or less commonly, hypotension.
- Once B/P parameter has been reached, IV infusion should not be restarted unless systolic B/P falls below 90 mm Hg.
- Taper dosage before discontinuing (abrupt cessation of therapy may result in marked hypotension).
- Be alert to excessive vasoconstriction (decreased urine output, increased heart rate, arrhythmias, disproportionate increase in diastolic B/P, decrease in pulse pressure); slow or temporarily stop infusion, notify physician.
REFERENCES:
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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