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Echothiophate

Authoritative Clinical Reference

Irreversible Cholinesterase Inhibitor (Organophosphate)

Drug Name: Echothiophate

Therapeutic Class: Cholinergic (Parasympathomimetic) Agent

Subclass: Irreversible Acetylcholinesterase Inhibitor (Organophosphate)

Schedule: Schedule H

Route(s): Ophthalmic (topical)

Formulations:


Formulation	Strength
Ophthalmic solution	0.03%

Note: Limited availability in India; often requires named-patient import or hospital-based compounding

ADULT INDICATIONS + DOSING

Primary Indications (Approved / Standard in India)

⮚ Chronic Open-Angle Glaucoma (Refractory Cases)


Parameter	Recommendation
Starting dose	0.03% solution — one drop once daily in affected eye(s)
Titration	Based on IOP response; increase to twice daily if needed after 2–4 weeks
Usual maintenance dose	0.03% once daily
Maximum dose	0.03% twice daily

Clinical Notes:

Onset of significant IOP reduction: 1–4 weeks
Miotic effect may persist days to weeks after discontinuation
Reserve for patients unresponsive to first-line agents (beta-blockers, prostaglandin analogues)
Discontinue immediately if signs of cataract progression or systemic organophosphate toxicity

⮚ Accommodative Esotropia (Specialist Use Only)


Parameter	Recommendation
Starting dose	0.03% solution — one drop once daily
Titration	Adjust based on ocular alignment and accommodation reduction under specialist guidance
Usual maintenance dose	0.03% once daily
Maximum dose	0.03% twice daily

Clinical Notes:

Used when surgical correction not feasible or as post-surgical adjunct
Short-term use recommended; consider periodic drug-free intervals
Requires paediatric ophthalmologist supervision

Secondary Indications – Adults (Off-label)

None documented or supported in Indian clinical practice.

PAEDIATRIC DOSING (Specialist Only)

Primary Indication: Accommodative Esotropia


Age Group	Dosing	Notes
≥2 years	0.03% — one drop once daily, may increase to twice daily based on response	Under paediatric ophthalmology supervision only
<2 years	NOT RECOMMENDED	High risk of systemic absorption and toxicity

Dosing Protocol:

Starting dose: 0.03% once daily in the affected eye
Titration: Increase to twice daily only if inadequate response after 2–4 weeks
Maximum dose: 0.03% twice daily
Duration: Short-term use preferred; periodic drug-free intervals advised

Safety Monitoring (Mandatory):

Pupillary size and ocular alignment at each visit
Signs of systemic cholinergic toxicity: excessive salivation, diarrhoea, bradycardia, bronchospasm
Growth and developmental milestones in prolonged use

⚠️ Minimum Age: Not recommended below 2 years except in exceptional circumstances under specialist supervision

Secondary Indications – Paediatric (Off-label)

None documented in Indian practice.

Renal Adjustments

Not applicable — Topical ophthalmic administration with minimal systemic absorption; no renal dose adjustment required.

Hepatic Adjustment


Impairment Severity	Recommendation
Mild	Not applicable — minimal systemic absorption
Moderate	Not applicable — minimal systemic absorption
Severe	Not applicable — minimal systemic absorption

Standard ophthalmic dosing may be used. Monitor for systemic cholinergic effects if any concern regarding hepatic metabolism of absorbed drug.

Contraindications

Known hypersensitivity to echothiophate iodide or other organophosphate compounds
Active uveitis or iritis
Narrow-angle glaucoma or anatomically narrow anterior chamber angle
History of or active retinal detachment
Use within 6 weeks prior to general anaesthesia involving succinylcholine or other depolarising neuromuscular blockers
Aphakia with intact posterior capsule (high risk of cystoid macular oedema)

Cautions

Long-term use associated with anterior and posterior subcapsular cataract formation — periodic lens examination required
Increased risk of retinal detachment in myopic patients or those with peripheral retinal pathology
Potential for systemic parasympathomimetic effects, especially in children or with excessive dosing/nasolacrimal absorption
Use with caution in patients with:
- Bronchial asthma
- Epilepsy
- Cardiac conduction abnormalities (bradyarrhythmias)
- Parkinsonism
- Peptic ulcer disease
May cause significant miosis leading to visual field restriction and difficulty with night vision
Digital nasolacrimal occlusion after instillation recommended to minimise systemic absorption

Pregnancy


Aspect	Recommendation
Safety category	Limited data; potential risk of systemic absorption affecting fetus
Preferred alternatives	Topical beta-blockers (e.g., timolol), prostaglandin analogues if essential
When may be used	Only if benefits clearly outweigh risks; obstetric and ophthalmology specialist input mandatory
Monitoring	Maternal cholinergic symptoms; fetal growth surveillance

Lactation


Aspect	Recommendation
Compatibility	Use with caution; insufficient human data
Drug levels in milk	Likely low due to minimal systemic absorption; not well studied
Preferred alternatives	Topical timolol for glaucoma in lactating women
Infant monitoring	Observe for cholinergic effects: poor feeding, excessive salivation, diarrhoea, lethargy, bradycardia

Elderly


Aspect	Recommendation
Starting dose	0.03% once daily
Titration	Slower titration recommended; reassess every 3–4 weeks
Special considerations	Increased risk of: cataract progression, retinal detachment, systemic bradycardia, visual field restriction leading to falls

Regular fundoscopy and lens examination essential
Educate regarding reduced night vision from miosis

Major Drug Interactions


Interacting Drug	Effect	Management
Succinylcholine	Echothiophate inhibits plasma cholinesterase → prolonged neuromuscular blockade, apnoea	Avoid — discontinue echothiophate at least 4–6 weeks before elective surgery
Other cholinesterase inhibitors (e.g., donepezil, rivastigmine, pyridostigmine)	Cumulative anticholinesterase toxicity	Avoid concurrent use; if essential, close monitoring for cholinergic crisis
Organophosphate insecticides	Additive cholinesterase inhibition	Avoid occupational exposure during treatment

Moderate Drug Interactions


Interacting Drug	Effect	Management
Beta-blockers (ophthalmic or systemic)	Enhanced bradycardia risk	Monitor heart rate; use with caution
Anticholinergic ophthalmics (e.g., tropicamide, cyclopentolate)	Antagonises miotic effect of echothiophate	Avoid concomitant use; allow washout period
Systemic anticholinergics (e.g., atropine, oxybutynin)	May reduce ocular efficacy	Monitor IOP response
Topical corticosteroid eye drops	Combined use may elevate IOP and accelerate cataract	Monitor IOP closely when used together
Carbamate insecticides	Additive cholinesterase inhibition	Advise patients to avoid exposure

Common Adverse Effects

Ocular stinging and discomfort on instillation
Persistent miosis
Blurred vision (especially in dim light)
Brow ache and periorbital headache
Conjunctival hyperaemia
Photophobia
Tearing (lacrimation)
Eyelid twitching (myokymia)

Serious Adverse Effects:


Adverse Effect	Clinical Notes
Systemic cholinergic toxicity	Bradycardia, hypotension, bronchospasm, excessive salivation, diarrhoea, arrhythmia — discontinue immediately
Retinal detachment	Higher risk with miotics; urgent ophthalmology referral required
Lens opacities	Anterior/posterior subcapsular cataract with prolonged use
Iris cysts	More common in children; may regress on discontinuation or with phenylephrine co-administration
Prolonged neuromuscular paralysis	If succinylcholine used during anaesthesia without adequate washout
Uveitis exacerbation	In predisposed patients

⚠️ Immediate discontinuation required if signs of systemic toxicity, retinal detachment, or severe ocular inflammation occur.

Monitoring Requirements:


Timing	Parameters
Baseline	Intraocular pressure, gonioscopy, fundoscopy (retinal periphery), lens clarity assessment
During initiation (2–4 weekly)	IOP measurement, pupillary response, signs of ocular inflammation
Ongoing (every 3–6 months)	Fundoscopy for retinal detachment; slit-lamp for cataract progression
Long-term (6–12 monthly)	Comprehensive anterior segment and fundus examination
Special (paediatrics)	Systemic cholinergic symptoms at each visit; iris cyst assessment; growth milestones

Brands in India

Phospholine Iodide 0.03% ophthalmic solution (limited availability; often imported)

Note: Availability in India is highly restricted. Many centres procure on named-patient basis or through hospital pharmacy compounding. Confirm current availability before prescribing.

Price Range (INR)


Formulation	Approximate Price
0.03% ophthalmic solution (5 mL)	₹300–500 (imported/compounded; variable)

Not listed under NLEM
Not under NPPA price control
Pricing highly variable due to limited supply and import dependency

Clinical Pearls

Reserve use for glaucoma refractory to first-line agents (prostaglandin analogues, beta-blockers, alpha agonists)
Pre-anaesthesia alert: Discontinue minimum 4–6 weeks before any surgery requiring succinylcholine; inform anaesthesiologist
Fundus examination mandatory before initiation and periodically thereafter due to retinal detachment risk
Nasolacrimal occlusion: Instruct patients to press on inner canthus for 2–3 minutes after instillation to reduce systemic absorption
Caregiver education essential in paediatric cases — counsel regarding signs of systemic toxicity (diarrhoea, bradycardia, breathing difficulty)
Night driving: Advise patients about reduced vision in dim light due to persistent miosis
Not a first-line agent — use only under specialist ophthalmology supervision

Version

RxIndia v1.0 — 02 Feb 2026

References

CDSCO (product registry and import documentation)
Indian Pharmacopoeia / National Formulary of India
AIIMS Ophthalmology Drug Protocols
Expert consensus from tertiary ophthalmology centres (India)
Goodman & Gilman's The Pharmacological Basis of Therapeutics, 13th Edition
API Textbook of Medicine, 21st Edition (relevant pharmacology sections)
Harrison's Principles of Internal Medicine, 20th Edition

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Clinical Responsibility

This platform is designed strictly for healthcare professionals. Data provided is synthesized from authoritative pharmacological sources and clinical registries. Do not use for consumer medical decisions. Always verify critical dosing and contraindications with official institutional protocols and peer-reviewed journals.

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