DrugindexOnline^{2nd edition}

Pronouncation: (eck-oh-THIGH-oh-fate EYE-oh-dide)
Class: Cholinesterase inhibitor

Trade Names:
Phospholine Iodide
- Powder for reconstitution 6.25 mg to make 0.125%

Mechanism of Action

Pharmacology

Causes miosis, increase in facility of outflow of aqueous humor, fall in IOP, and potentiation of accommodation by enhancing the effect of endogenously liberated acetylcholine in the iris, ciliary muscle, and other parasympathetic innervated structures of the eye.

Indications and Usage

Treatment of chronic open-angle glaucoma; treatment of accommodative esotropia.

Contraindications

Active uveal inflammation; most cases of angle-closure glaucoma because of the possibility of increasing angle block; hypersensitivity to any component of the product.

Dosage and Administration

Glaucoma

Ophthalmic Use the lowest concentration that will control the IOP around-the-clock. Two doses a day are preferred to one in order to maintain as smooth a diurnal tension curve as possible.

Early chronic simple glaucoma

Instill 0.03% twice daily, just before bedtime and in the morning.

Advanced chronic simple glaucoma and glaucoma secondary to cataract surgery

Instill 0.03% twice daily. When transferring to echothiophate because of unsatisfactory control with one of the other agents, one of the higher strengths of echothiophate iodide may be needed. In this case, a brief trial with 0.03% may be advantageous in that the higher strengths then will be more easily tolerated.

Accommodative Esotropia
Children

Ophthalmic Diagnosis: Instill 1 drop of 0.125% once daily in both eyes on retiring, for 2 to 3 wk. If esotropia is accommodative, a favorable response will usually be noted within a few hours. Treatment: Use the lowest concentration and frequency that gives satisfactory results. After initial period for diagnostic purposes, the schedule may be reduced to 0.125% every other day or 0.06% every day. Often the dosage can be gradually reduced as treatment progresses.

General Advice

• For topical ophthalmic use only. Not for injection into the eye.
• If using other topical ophthalmic drugs, separate each medication by at least 5 min.

Storage/Stability

Store unopened bottles with powder for reconstitution in refrigerator (36° to 46°F). Reconstituted eye drops may be stored at controlled room temperature (77°F) for up to 4 wk. Discard any unused solution after 4 wk.

Drug Interactions

Cholinesterase inhibitors (eg, succinylcholine), organophosphate and carbamate insecticides

The effects of these agents may be potentiated by echothiophate.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Cardiac irregularities.

EENT

Activation of latent iritis or uveitis; brow ache; burning; conjunctival and ciliary redness; conjunctival thickening; induced myopia with visual blurring; iris cysts, which may obscure vision; lacrimation; lens opacities; lid muscle twitching; obstruction of nasolacrimal canals; paradoxical increases in IOP; retinal detachment; stinging.

Precautions

Monitor IOP Ensure IOPs are measured and documented in the patient's record before starting therapy and periodically thereafter. Inform health care provider of abnormal pressures. Be prepared to change therapy if IOPs are not controlled with echothiophate iodide. Adverse reactions Monitor patient for development of cardiac arrhythmias, excessive salivation, urinary incontinence, diarrhea, profuse sweating, muscle weakness, or respiratory difficulties. Inform health care provider if noted. Be prepared to temporarily discontinue medication.

Pregnancy

Category C .

Lactation

Because of potentially serious adverse reactions in breast-feeding infants, decide whether to discontinue breast-feeding or the drug.

Special Risk Patients

Use with extreme caution, if at all, in patients with a history of retinal detachment or in patients with marked vagotonia, bronchial asthma, spastic GI disturbances, peptic ulcer, pronounced bradycardia and hypotension, recent MI, epilepsy, parkinsonism, and other disorders that may respond adversely to vagotonic effects. Temporarily discontinue if salivation, urinary incontinence, diarrhea, profuse sweating, muscle weakness, or respiratory difficulties occur.

Gonioscopy

Routine examination to detect lens opacity should accompany use of echothiophate.

Uveitis

Avoid use or use with caution in patients with quiescent uveitis or a history of this condition because of the possibility of intense and persistent miosis and ciliary muscle contraction.

Patient Information

• Advise patient that usual dose is 1 drop in the affected eye(s) once or twice daily. Advise patient using 1 instillation/day to instill eye drops just before bedtime. Advise patient using 2 instillations/day to instill eye drops first thing in the morning and just before bedtime.
• Teach patient proper technique for instilling eye drops: Wash hands. Do not allow dropper tip to touch eye. Tilt head back, look up; pull lower eyelid down; instill prescribed number of drops. Close eye for 1 to 2 min and apply gentle pressure to bridge of nose for 1 to 2 min. Do not rub eye. Wash hands after instilling eye drops.
• Advise patient that if more than 1 topical ophthalmic drug is being used, administer the drugs at least 5 min apart.
• Inform patient that this medication may cause stinging, burning, tearing, eyelid muscle twitching, browache, eye redness, and blurred vision. Advise patient to notify eye doctor if any of these occur and are bothersome or intolerable.
• Instruct patient to immediately notify eye doctor if any of the following occur: eye or eyelid irritation; abnormal heart rhythm; excessive salivation; urinary incontinence; diarrhea; profuse sweating; muscle weakness; or respiratory difficulties.
• Remind patient that eye examinations and measurement of IOP will be necessary while using this medication and to keep appointments.