IHEEZO
Clinical safety rating: caution
Comprehensive clinical and safety monograph for IHEEZO (IHEEZO).
Iheezo (phentolamine ophthalmic solution) is an alpha-adrenergic antagonist that inhibits sympathetic tone to the iris dilator muscle, preventing mydriasis and facilitating pupil constriction during ocular surgery.
| Metabolism | Systemic absorption is negligible; metabolism, if any, is likely via hepatic enzymes similar to systemic phentolamine (minimal data for ophthalmic formulation). |
| Excretion | IHEEZO (proparacaine) is predominantly metabolized by plasma esterases; less than 5% is excreted unchanged in urine. Biliary/fecal elimination is negligible. |
| Half-life | The terminal elimination half-life of proparacaine is approximately 1-2 minutes due to rapid hydrolysis by plasma esterases, resulting in a very short duration of systemic exposure. |
| Protein binding | Proparacaine is approximately 75% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | The volume of distribution of proparacaine is not well characterized due to rapid metabolism; estimated Vd is low (<1 L/kg) reflecting limited tissue distribution. |
| Bioavailability | Ophthalmic: Systemic bioavailability is negligible due to rapid local hydrolysis and small administered dose. Oral bioavailability is not applicable due to extensive first-pass metabolism. |
| Onset of Action | Ophthalmic: Anesthetic effect occurs within 20-30 seconds after instillation. |
| Duration of Action | Ophthalmic: Anesthesia lasts approximately 15-20 minutes, sufficient for short procedures; prolonged use may cause corneal toxicity. |
1 drop in the affected eye(s) 3 times daily as needed for relief of ocular discomfort. For optimal use, administer at least 10 minutes apart from other ophthalmic medications.
| Dosage form | GEL |
| Renal impairment | Not required; IHEEZO undergoes minimal systemic absorption and renal impairment does not affect its ocular efficacy or safety. |
| Liver impairment | Not required; hepatic impairment does not alter the pharmacokinetics of IHEEZO due to negligible systemic absorption. |
| Pediatric use | 1 drop in the affected eye(s) up to 3 times daily as needed for children aged 3 years and older. Safety and efficacy in children under 3 years have not been established. |
| Geriatric use | No dose adjustment necessary; elderly patients may use the standard adult dose. Caution in those with severe dry eye syndrome or concurrent ocular conditions. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for IHEEZO (IHEEZO).
| Breastfeeding | Apraclonidine is excreted in human milk in low concentrations; the M/P ratio is unknown. Ophthalmic administration results in negligible systemic levels. Use with caution in nursing mothers due to potential for infant exposure to alpha-2 agonists, although risk is considered low. |
| Teratogenic Risk | IHEEZO (apraclonidine ophthalmic) is not systemically absorbed in significant amounts. No fetal risks have been identified from clinical use; however, no well-controlled studies in pregnant women exist. Animal studies show no teratogenic effects at doses far exceeding ophthalmic exposure. FDA Pregnancy Category C. First trimester: theoretical risk minimal. Second and third trimesters: no known fetal adverse effects. |
■ FDA Black Box Warning
No boxed warning.
| Serious Effects |
["Hypersensitivity to phentolamine or any component of the formulation.","Active iritis or uveitis.","Narrow-angle glaucoma or anatomically narrow angles.","Concurrent use of alpha-adrenergic agonists for ocular procedures."]
| Precautions | ["Avoid use in patients with narrow-angle glaucoma or anatomically narrow angles due to risk of angle closure.","Do not administer concurrently with other alpha-adrenergic antagonists or drugs that may cause miosis, as additive effects may occur.","Use with caution in patients with a history of iritis or uveitis, as pupil constriction may be incomplete."] |
Loading safety data…
| Fetal Monitoring | No specific monitoring required beyond standard ophthalmic follow-up. Monitor for maternal systemic adverse effects (e.g., bradycardia, hypotension) if excessive dosing or accidental ingestion occurs. |
| Fertility Effects | No known effects on fertility based on available data. Ophthalmic use with minimal systemic absorption is unlikely to impact reproductive function. |