Question

Medication templates, epinephrine, expected pharmacological action, therapeutic use, complications, medication administration, contraindications,nursing interventions, interaction, client education, and evaluation of medication effectiveness

Answer 1

Mechanism of Action:

• It is a sympathomimetic catecholamine that exerts its pharmacologic effects on both alpha and beta-adrenergic receptors using a G protein-linked second messenger system. It has a greater affinity for beta receptors in small doses.
• Through its action on alpha-1 receptors, epinephrine induces increased vascular smooth muscle contraction, pupillary dilator muscle contraction, and intestinal sphincter muscle contraction.
• Other significant effects include increased heart rate, myocardial contractility, and renin release via beta-1 receptors.
• Beta-2 effects produce bronchodilation, which may be useful as an adjunct treatment of asthma exacerbations as well as vasodilation, tocolysis, and increased aqueous humor production.

Uses:

• IV: In ventricular standstill after all other measures have failed to restore circulation, given by trained personnel by intracardiac puncture and intramyocardial injection; treatment and prophylaxis of cardiac arrest and attacks of transitory AV heart block with syncopal seizures (Stokes-Adams syndrome); syncope due to carotid sinus syndrome; acute hypersensitivity (anaphylactoid) reactions, serum sickness, urticaria, angioneurotic edema; in acute asthmatic attacks to relieve bronchospasm not controlled by inhalation or subcutaneous injection; relaxation of uterine musculature; additive to local anesthetic solutions for injection to prolong their duration of action and limit systemic absorption
• Injection: Relief from respiratory distress of bronchial asthma, chronic bronchitis, emphysema, other COPDs
• Aerosols and solutions for nebulization: Temporary relief from acute attacks of bronchial asthma, COPD
• Topical nasal solution: Temporary relief from nasal and nasopharyngeal mucosal congestion due to a cold, sinusitis, hay fever, or other upper respiratory allergies; adjunctive therapy in middle ear infections by decreasing congestion around eustachian ostia
• 0.1% ophthalmic solution: Conjunctivitis, during eye surgery to control bleeding, to produce mydriasis.

Administration:

Depending on the diagnosis, epinephrine administration can be in various forms. For the treatment of anaphylaxis, epinephrine is preferably injected intramuscularly into the anterolateral aspect of the thigh due to rapid absorption or subcutaneously as well. For advanced cardiovascular life support (ACLS), patients can receive epinephrine intravenously or intraosseous if needed. Another route of administration is through an endotracheal tube often used in neonatal resuscitation.

Complications:

• Central nervous system (CNS): Anxiety, dizziness, nervousness, agitation, headache, Parkinson’s disease exacerbation

• Cardiovascular: Arrhythmias, chest pain, hypertension, palpitations, tachycardia, cerebrovascular accidents, ventricular ectopy, vasospasm, tissue ischemia

• Dermatologic: Gangrene at the injection site (especially in buttocks), skin necrosis with extravasation

• Endocrine: Hyperglycemia, hypokalemia, lactic acidosis

• Gastrointestinal: Nausea, vomiting, increase in AST and ALT

• Neuromuscular: Tremors, weakness

• Renal: Decreased renal perfusion

• Respiratory: Dyspnea, pulmonary edema

Contraindications:

Some relative contraindications include hypersensitivity to sympathomimetic drugs, closed-angle glaucoma, anesthesia with halothane.

Pregnancy: . It is capable of crossing the placenta. Epinephrine use requires caution when maternal blood pressure is 130/80 mm Hg and greater.

Labor and Delivery:

Due to its effect on beta-2 adrenergic receptors causing tocolysis, epinephrine opposes the actions of oxytocin on the uterus and may delay labor. It also requires caution during anaphylaxis induced hypotension in pregnancy as it may lead to uterine vasoconstriction, thus decreasing oxygen delivery to the fetus

Pediatrics

Epinephrine is effective at a dilution of between 1 to 100,000 and 1 to 400,000 for mydriasis induction and maintenance in pediatric intraocular surgeries.

Geriatrics

Due to the expected decrease in renal, hepatic, and cardiac function of geriatric patients, epinephrine should be started at the lower end of the dosing regime and titrated appropriately for clinical effect.

Interactions:

• Alpha-adrenergic blockers: Antagonizes pressor effects

• Antihypertensives: Antagonizes pressor effects

• Vasodilators: Antagonizes pressor effects

• Diuretics: Antagonizes pressor effects

• Beta-adrenergic blockers: Potentiates pressor effects

• Monoamine oxidase (MAO) inhibitors: Potentiates pressor effects

• Catechol-o-methyltransferase (COMT) inhibitors: Potentiates pressor effects

Nursing Interventions:

• Use extreme caution when calculating and preparing doses; epinephrine is a very potent drug; small errors in dosage can cause serious adverse effects. Double-check pediatric dosage.
• Use minimal doses for minimal periods of time; “epinephrine-fastness” (a form of drug tolerance) can occur with prolonged use.
• Protect drug solutions from light, extreme heat, and freezing; do not use pink or brown solutions. Drug solutions should be clear and colorless (does not apply to suspension for injection).
• Shake the suspension for injection well before withdrawing the dose.
• Rotate subcutaneous injection sites to prevent necrosis; monitor injection sites frequently.
• Keep a rapidly acting alpha-adrenergic blocker (phentolamine) or a vasodilator (a nitrate) readily available in case of excessive hypertensive reaction.
• Have an alpha-adrenergic blocker or facilities for intermittent positive pressure breathing readily available in case pulmonary edema occurs.
• Do not exceed recommended dosage of inhalation products; administer pressurized inhalation drug forms during second half of inspiration, because the airways are open wider and the aerosol distribution is more extensive. If a second inhalation is needed, administer at peak effect of previous dose, 3–5 min.
• Use topical nasal solutions only for acute states; do not use for longer than 3–5 days, and do not exceed recommended dosage. Rebound nasal congestion can occur after vasoconstriction subsides.

Evaluation:

When administered parenterally, epinephrine has a rapid onset, but a short duration of action. When given intravenously, it has a half-life of fewer than 5 minutes. Metabolism is primarily in the liver, along with various other locations such as the kidneys, skeletal muscle, and mesenteric organs.

Certain effects need monitoring. Tachycardia and hypertension are expected effects when giving epinephrine intravenously, so it is important to titrate the drug carefully while monitoring hemodynamics. Epinephrine is also used with anesthetic agents to provide analgesia. In locations where extravasation of epinephrine has occurred, prevention and treatment of ischemia-induced necrosis are necessary. The infiltrated area should receive treatment with a 10 mL to 15 mL saline solution containing 5 mL to 10 mg of phentolamine, an alpha-adrenergic blocking agent.

Renal impairment requires monitoring as epinephrine causes renal blood vessel constriction and can decrease urine impairment.

During intraocular use, epinephrine requires dilution; otherwise, corneal endothelial damage can result with the administration of undiluted concentrations of sodium bisulfite.

Client education:

Inform the client not to exceed recommended dosage; adverse effects or loss of effectiveness may result. Read the instructions that come with respiratory inhalant products, and consult the health care provider or pharmacist for any questions.

To give eye drops: Lie down or tilt head backward, and look up. Hold dropper above eye; drop medicine inside lower lid while looking up. Do not touch dropper to eye, fingers, or any surface. Release lower lid; keep eye open, and do not blink for at least 30 seconds. Apply gentle pressure with fingers to inside corner of the eye for about 1 minute; wait at least 5 minutes before using other eye drops.

Inform the client that he may experience these side effects: Dizziness, drowsiness, fatigue, apprehension (use caution if driving or performing tasks that require alertness); anxiety, emotional changes; nausea, vomiting, change in taste (eat frequent small meals); fast heart rate. Nasal solution may cause burning or stinging when first used (transient). Ophthalmic solution may cause slight stinging when first used (transient); headache or brow ache (only during the first few days).

Report chest pain, dizziness, insomnia, weakness, tremor or irregular heart beat (respiratory inhalant, nasal solution), difficulty breathing, productive cough, failure to respond to usual dosage (respiratory inhalant), decrease in visual acuity (ophthalmic).