Phospholine Iodide
echothiophate 0.125% · ophthalmic solution
Antiglaucoma, Misc.
Approved uses
Elevated intraocular pressure
1 drop of 0.125% twice daily, just before retiring and in the morning; may be reduced to once daily or every other day
Added to maximal therapy, 75% of eyes dropped 20% or more, responders falling from about 30 to 17 mmHg.
Concomitant esotropia with a significant accommodative component
Diagnosis: 1 drop of 0.125% in both eyes on retiring for two or three weeks. Treatment: lowest effective frequency, usually a maximum of 1 drop once a day, often 1 drop every other day
Contraindications
- Active uveal inflammation.
- Most cases of angle-closure glaucoma without iridectomy, due to the possibility of increasing angle block.
- Hypersensitivity to the active or inactive ingredients.
Available FormsOphthalmic solution, 0.125% (6.25 mg package supplied with diluent and dropper for 5 mL of eyedrops)
Mechanism of ActionLong-acting cholinesterase inhibitor that enhances endogenously liberated acetylcholine at the iris, ciliary muscle, and other parasympathetically innervated ocular structures, causing miosis, increased facility of aqueous outflow, a fall in IOP, and potentiation of accommodation. Topical therapy depresses both plasma and erythrocyte cholinesterase in most patients after a few weeks, which is what underlies the succinylcholine and organophosphate interactions.
Warnings & Precautions
- Succinylcholine and general anesthesia: Possible respiratory or cardiovascular collapse, so succinylcholine should be given only with great caution, if at all, before or during general anesthesia in a patient on anticholinesterase medication.
- Systemic anticholinesterase therapy: Caution when treating elevated IOP in a patient concurrently on systemic anticholinesterase medication, because of possible additive effects.
- Organophosphate and carbamate exposure: Patients exposed to these insecticides and pesticides should be warned of additive systemic effects from respiratory tract or skin absorption; respiratory masks, frequent washing, and clothing changes may be advisable during exposure.
- Cholinergic symptoms: Temporary discontinuance is necessary if salivation, urinary incontinence, diarrhea, profuse sweating, muscle weakness, or respiratory difficulty occurs.
- Cardiac irregularities: Discontinue if they occur.
- Vagotonic conditions: Caution, if used at all, in marked vagotonia, bronchial asthma, spastic gastrointestinal disturbance, peptic ulcer, pronounced bradycardia and hypotension, recent myocardial infarction, epilepsy, parkinsonism, and other disorders that may respond adversely to vagotonic effects.
- Prior retinal detachment: Caution where there is a prior history.
- Systemic absorption: Digital compression of the nasolacrimal ducts for a minute or two after instillation reduces drainage into the nasal chamber, and hands should be washed afterward to prevent skin absorption.
- Examinations in accommodative esotropia: Regular examinations are advisable while the drug is prescribed for this indication.
Common Side Effects
- Ocular, common: Stinging, burning, lacrimation, lid muscle twitching, conjunctival and ciliary redness, browache, and induced myopia with visual blurring.
- Ocular, prolonged use: Conjunctival thickening, obstruction of the nasolacrimal canals, and lens opacities.
- Iris cysts: May form and, if treatment continues, enlarge and obscure vision; more frequent in children, usually shrinking when the drug is stopped or the frequency reduced, and rarely rupturing or breaking free into the aqueous.
- Paradoxical IOP rise: May follow anticholinesterase instillation and may be alleviated by prescribing a sympathomimetic mydriatic such as phenylephrine.
- Latent inflammation: Activation of latent iritis or uveitis.
- Retinal detachment: Reported in a few adult cases without previous history of the disorder, with the relationship to the drug not established.
- Systemic: Cardiac irregularities.
Pregnancy & LactationPregnancy: Animal reproduction studies have not been conducted and fetal harm potential is unknown; give only if clearly needed.
Lactation: Because of the potential for serious adverse reactions in a nursing infant, decide whether to stop nursing or stop the drug, weighing its importance to the mother.
Pediatric UseSafety and effectiveness established; iris cysts occur more frequently in children.