A fixed-dose ophthalmic combination of a sympathomimetic mydriatic (Phenylephrine) and an antimuscarinic cycloplegic (Tropicamide). Primarily used for diagnostic procedures to achieve rapid, maximal mydriasis (pupil dilation) and cycloplegia (paralysis of accommodation). Phenylephrine acts on alpha-1 adrenergic receptors of the iris dilator muscle, while Tropicamide blocks muscarinic receptors of the iris sphincter and ciliary muscle. This combination provides synergistic action, making it a standard in ophthalmic examinations, especially for fundoscopy and refractive error assessment in children.
Adult: For diagnostic procedures: Instill 1-2 drops into the conjunctival sac of the eye(s) to be examined, 15-30 minutes before the procedure. A second drop may be required after 5 minutes for maximal effect in dark irides.
Note: 1. Wash hands. 2. Tilt head back. 3. Gently pull lower eyelid down to form a pouch. 4. Instill prescribed number of drops into the pouch without touching the dropper tip to eye or any surface. 5. Close eyes gently and apply pressure to the nasolacrimal duct (inner corner of eye) for 1-2 minutes (punctal occlusion) to reduce systemic absorption. 6. Wait at least 5-10 minutes before instilling any other eye drops.
The combination produces mydriasis (pupil dilation) and cycloplegia (paralysis of accommodation) through two distinct receptor pathways. Phenylephrine, a direct-acting alpha-1 adrenergic agonist, stimulates the radial (dilator) muscle of the iris, causing it to contract and dilate the pupil. Tropicamide, an antimuscarinic agent, competitively blocks acetylcholine receptors on the circular (sphincter) muscle of the iris and the ciliary muscle. This blockade causes sphincter relaxation (adding to mydriasis) and ciliary muscle paralysis, leading to loss of accommodation (cycloplegia).
Pregnancy: Category C (US FDA). Animal reproduction studies have not been conducted. Use only if clearly needed and potential benefit justifies potential risk to the fetus. Systemic absorption can cause fetal tachycardia and vasoconstriction.
Driving: STRICTLY NOT ADVISED until vision returns to normal (blurring and photophobia subside), which can take 4-24 hours. Patients must not drive or operate hazardous machinery after instillation.
| Monoamine Oxidase Inhibitors (MAOIs) e.g., Phenelzine, Tranylcypromine | Markedly potentiates the pressor effects of phenylephrine, leading to severe hypertension and hyperpyrexia. | Contraindicated / Major |
| Tricyclic Antidepressants (TCAs) e.g., Amitriptyline, Imipramine | Potentiates the pressor response to phenylephrine due to inhibition of neuronal reuptake. | Major |
| Beta-blockers (Non-selective) e.g., Propranolol, Timolol (ophthalmic) | Unopposed alpha-adrenergic stimulation can lead to severe hypertension and bradycardia. | Major |
| Atropine or other systemic anticholinergics | Additive systemic anticholinergic effects (dry mouth, tachycardia, confusion) with tropicamide. | Moderate |
| Levodopa | Increased risk of cardiac arrhythmias with phenylephrine. | Moderate |
| Digoxin | Increased risk of arrhythmias with phenylephrine-induced tachycardia. | Moderate |
| Other topical mydriatics/cycloplegics | Additive ocular effects. | Moderate |
Same composition (Phenylephrine (5% w/v) + Tropicamide (0.8% w/v)), different brands: