Drug Guide
Hydroxyamphetamine Hydrobromide; Tropicamide
Classification
Therapeutic: Mydriatic and Cycloplegic Agent
Pharmacological: Sympathomimetic and Anticholinergic
FDA Approved Indications
- Mydriasis for fundoscopic examination
- Cycloplegia during ophthalmic examination
Mechanism of Action
Hydroxyamphetamine stimulates adrenergic receptors in the dilator muscle of the iris, causing mydriasis; Tropicamide blocks parasympathetic conduction by antagonizing muscarinic receptors, resulting in pupil dilation and paralysis of accommodation.
Dosage and Administration
Adult: 1 drop in the affected eye, may repeat every 5-10 minutes for up to 2 doses.
Pediatric: Same as adults, with cautious use; consult specific pediatric guidelines.
Geriatric: Use with caution; monitor for sensitivities.
Renal Impairment: Adjust as clinically indicated; data limited.
Hepatic Impairment: Use with caution; no specific dosing guidelines available.
Pharmacokinetics
Absorption: Rapid absorption following ocular instillation.
Distribution: Primarily localized at site of action, minimal systemic absorption.
Metabolism: Minimal systemic metabolism; some systemic metabolism may occur.
Excretion: Systemic excretion through renal pathways.
Half Life: Approximate systemic half-life: Hydroxyamphetamine (~6 hours), Tropicamide (~3 hours).
Contraindications
- Hypersensitivity to any component.
- Pre-existing angle-closure glaucoma.
Precautions
- Use with caution in patients with cardiac conditions, hypertension, or hypersensitivity reactions.
- Caution in children, the elderly, and those with hepatic or renal impairment.
- Use in pregnancy and lactation should be based on risk-benefit assessment.
Adverse Reactions - Common
- Transient stinging or burning in the eyes. (Common)
- Blurred vision. (Common)
- Photophobia. (Common)
Adverse Reactions - Serious
- Increased intraocular pressure, especially in closed-angle glaucoma. (Rare)
- Allergic reactions, including conjunctivitis and eyelid edema. (Rare)
- Systemic effects such as tachycardia, hypertension, or CNS effects. (Rare)
Drug-Drug Interactions
- Other mydriatic agents, cycloplegics, or medications affecting heart rate or blood pressure.
Drug-Food Interactions
- None significant.
Drug-Herb Interactions
- None significant.
Nursing Implications
Assessment: Assess baseline pupil size and ocular condition before administration.
Diagnoses:
- Risk for increased intraocular pressure.
- Potential for impaired vision temporarily.
Implementation: Administer as prescribed, monitor for adverse reactions, and ensure proper patient education.
Evaluation: Assess pupil dilation and patient comfort post-administration.
Patient/Family Teaching
- Instruct patients to avoid driving or operating machinery until effects wear off.
- Warn about temporary blurring of vision and sensitivity to light.
- Encourage reporting of persistent eye discomfort or systemic side effects.
Special Considerations
Black Box Warnings:
- None currently.
Genetic Factors: None identified.
Lab Test Interference: May interfere with certain diagnostic tests involving iris function or pupil response.
Overdose Management
Signs/Symptoms: Systemic toxicity may include tachycardia, hypertension, agitation, or hallucinations.
Treatment: Supportive care; monitor cardiovascular and neuro status; activated charcoal if ingestion is recent (mainly for systemic overdose).
Storage and Handling
Storage: Store at room temperature, protected from light and moisture.
Stability: Stable under recommended storage conditions for the duration of the shelf life.