Antimalarial — Ophthalmic Toxicity Monitoring Drug Pregnancy: Compatible with pregnancy — used in SLE during pregnancy under specialist guidance; does not cross placenta significantly

Hydroxychloroquine (Ophthalmic Toxicity Monitoring)

Brand names: Plaquenil

Adult dose

Dose: Not an ophthalmic drug — systemic drug (200–400 mg/day orally) used in rheumatology/dermatology. Listed here for ophthalmic toxicity monitoring protocol

Route: Oral (systemic — prescribed by rheumatologist/dermatologist)

Frequency: Once or twice daily

Max: 5 mg/kg/day based on ideal body weight — key RCOphth 2018 safety threshold

CRITICAL DOSE THRESHOLD: do not exceed 5 mg/kg/day based on actual (lean) body weight — doses above this dramatically increase retinopathy risk. Ophthalmology screening mandatory. Royal College of Ophthalmologists (RCOphth) 2018 guidelines define the monitoring schedule.

Paediatric dose

Dose: 5 mg/kg

Route: Oral

Frequency: Once daily

Max: 5 mg/kg/day

JIA treatment — ophthalmic monitoring still required; lower cumulative dose in children reduces long-term risk

Dose adjustments

Renal

Reduce dose in renal impairment (eGFR <30 mL/min) — hydroxychloroquine renal clearance reduced; toxicity risk increased

Hepatic

Use with caution in hepatic impairment — reduced clearance

Paediatric weight-based calculator

Patient weight (kg)

JIA treatment — ophthalmic monitoring still required; lower cumulative dose in children reduces long-term risk

Clinical pearls

RCOphth 2018 monitoring guidelines: baseline ophthalmology assessment before or within 1 year of starting; annual screening from year 5 of treatment (when cumulative retinopathy risk begins to increase significantly). Screening: OCT (central and pericentral maps) + visual field test (10-2 pattern) ± multifocal ERG
Dose threshold: 5 mg/kg/day based on ACTUAL body weight (lean body mass in obese patients) is the key safety threshold — at ≤5 mg/kg/day, 10-year retinopathy risk is <1%; at >6 mg/kg/day, risk exceeds 4% at 10 years (Melles & Marmor 2014 study)
Asian patients at higher risk: Asians (particularly East Asian — Korean, Japanese, Chinese patients) develop a pericentral pattern of retinopathy (rather than the classic bull's-eye paracentral pattern seen in white Caucasians) — this can be missed by standard 10-2 visual fields; OCT is essential and 24-2 visual field testing recommended in Asian patients
Bull's-eye maculopathy is IRREVERSIBLE: once true bull's-eye maculopathy develops, visual loss is permanent and may progress even after stopping — early detection via annual monitoring is the only preventive strategy
MHRA 2017: Risk of serious retinal toxicity confirmed; prescribers must adhere to dose limit of 5 mg/kg/day and ensure annual ophthalmological monitoring is arranged and attended

Contraindications

Pre-existing macular disease or significant visual field defects
Glucose-6-phosphate dehydrogenase (G6PD) deficiency (haemolysis risk)
Hypersensitivity to 4-aminoquinolines

Side effects

Retinal toxicity (bull's-eye maculopathy) — dose-dependent and cumulative; IRREVERSIBLE
Visual field defects — paracentral scotoma is earliest detectable change
GI effects — nausea, diarrhoea
Skin pigmentation
Cardiomyopathy (rare — prolonged use)

Interactions

Drugs prolonging QTc — additive risk; avoid concurrent use
Antiepileptics — hydroxychloroquine may lower seizure threshold
Digoxin — hydroxychloroquine increases digoxin levels

Monitoring

Annual ophthalmology screening from year 5 (OCT + visual fields 10-2)
24-2 visual field in Asian patients
Baseline visual acuity and colour vision
Renal function (dose adjustment in CKD)

Reference: BNFc; BNF 90; RCOphth Hydroxychloroquine Monitoring Guidelines 2018; MHRA DSU 2017; Melles & Marmor (JAMA Ophthalmol 2014); BSR/BHPR Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways