Hydroxychloroquine

Plaquenil is indicated for acute/chronic rheumatoid arthritis, systemic lupus erythematosus and chronic discoid lupus erythematosus in adults. Pediatric rheumatic-disease safety/effectiveness are not established by this U.S. label; specialist use is a separate off-label decision. Porphyria cutanea tarda treatment is not approved and is specifically cautioned against.

The label covers uncomplicated malaria due to susceptible P. falciparum, P. malariae, P. vivax and P. ovale, and prophylaxis only where chloroquine resistance is absent. It is not recommended for complicated malaria, resistant strains, unidentified species or resistant geographic acquisition. It does not eradicate P. vivax/P. ovale liver hypnozoites: relapse prevention requires a separately selected 8-aminoquinoline with appropriate safety assessment. Consult current CDC resistance guidance rather than assuming country-wide susceptibility.

RA label initial dosing is 400–600 mg/day once daily or in two divided doses, with chronic dosing 200–400 mg/day. SLE and discoid lupus: 200 mg daily or 400 mg daily as one or two doses. Benefit is cumulative and may take weeks to months. Reconcile any high initial dose with actual-weight retinal risk and the monitoring plan rather than treating 600 mg as a routine chronic target. Take with food or milk.

The 2025 AAO revision retains a daily limit of ≤5 mg/kg actual body weight and advises staying under 400 mg/day in severe obesity. This retinal-risk guidance must be reconciled with the label’s broader RA initial range and intact tablet sizes. It is not an acute malaria loading-dose cap. The clinician should select a feasible regimen and monitor risk; do not split Plaquenil tablets to approximate a dose.

Start 2 weeks before exposure; take once weekly on the same day during exposure and for 4 weeks after leaving. Adults: 400 mg sulfate weekly. Pediatric patients ≥31 kg: 6.5 mg/kg actual weight, maximum 400 mg weekly. Plaquenil is not recommended below 31 kg because its lowest 200-mg tablet cannot be divided; do not invent a compounded-product regimen from this label.

Adults: 800 mg sulfate initially, then 400 mg at 6, 24 and 48 hours (adult total 2,000 mg). Pediatric patients ≥31 kg: 13 mg/kg initially, maximum 800 mg, then 6.5 mg/kg, maximum 400 mg, at 6, 24 and 48 hours. Species, acquisition region and an appropriate deliverable formulation require specialist assessment. The label’s printed pediatric total is internally inconsistent with these component doses; no inconsistent total is reproduced.

Known hypersensitivity to 4-aminoquinoline compounds is the formal Plaquenil contraindication. Retinal, cardiac, psoriasis and porphyria restrictions are addressed as warnings/avoidance recommendations rather than additional entries in the formal contraindications section.

The current selected U.S. label has no boxed warning. Its potentially fatal arrhythmia, overdose and serious skin warnings still require explicit counseling.

Reported reactions include nausea, vomiting, diarrhea, abdominal pain, rash, itching, headache, pigment/hair changes and the serious effects above; postmarketing frequency estimates are unreliable. Overdose can rapidly cause lethal arrhythmia, hypotension, hypokalemia, seizures or coma, often within 1–3 hours. Seek emergency/poison-center help immediately; U.S. Poison Help is 1-800-222-1222. Dialysis techniques do not help according to the label. No home decontamination instruction or “safe excess dose” is provided.

Avoid other QT-prolonging or arrhythmogenic medicines. Insulin/antidiabetic effects can increase: monitor glucose and adjust through the prescriber. Monitor digoxin and cyclosporine concentrations. Methotrexate can increase adverse effects. Tamoxifen adds retinal risk, making dose and screening reassessment important.

Avoid rifampicin because lack of efficacy has been reported and avoid cimetidine because related chloroquine exposure increases. Mefloquine/other seizure-threshold-lowering antimalarials can increase seizures and antiepileptic activity may be impaired. Antacid/kaolin, ampicillin and praziquantel interactions are based on chloroquine data and cannot be excluded for hydroxychloroquine; the label cites at least 4-hour antacid/kaolin separation for chloroquine. Review these combinations without presenting extrapolated evidence as a proven hydroxychloroquine dose algorithm.

Decades of use and available pregnancy studies have not identified a drug-associated major malformation, miscarriage or adverse pregnancy-outcome risk, but studies have limitations. Untreated malaria or active rheumatic disease also creates maternal/fetal risks; hydroxychloroquine crosses the placenta. Milk levels are low, with no reported infant adverse reactions in the label’s published data; effects on milk production are unknown. Balance maternal benefit and breastfeeding needs rather than asserting zero risk.

Malaria pediatric use is established, but this intact-tablet product is unsuitable below 31 kg. Pediatric RA/SLE/discoid lupus use is not established by the selected label. Older-adult trials were limited; begin at the low recommended range while considering renal/hepatic/cardiac function and polypharmacy. The AAO revision also recognizes older age at initiation as a retinal-risk factor.

The label says dose reduction may be needed with renal or hepatic disease, without a numeric eGFR/Child-Pugh algorithm. Renal impairment additionally increases retinal risk. New proteinuria or reduced renal function may reflect drug phospholipidosis as well as underlying disease. With symptoms of liver injury, measure liver tests promptly and interrupt/investigate significant abnormalities as directed, especially with possible porphyria cutanea tarda.

This 4-aminoquinoline acts on erythrocytic chloroquine-sensitive malaria forms; the precise antimalarial mechanism is incompletely defined and may involve parasite acid-vesicle concentration and heme processing. Rheumatic anti-inflammatory/immunomodulatory mechanisms are not fully known. It does not clear liver hypnozoites.

Mean oral bioavailability is about 79%; tissue distribution is extensive and protein binding approximately 50%. Hepatic metabolism includes CYP2C8/3A4/2D6 pathways, and unchanged renal clearance accounts for about 16–30% of dose. The chronic whole-blood terminal half-life is about 40–50 days; this is not the dosing interval or a guaranteed duration of therapeutic benefit.

The label advises baseline examination within the first year and annual assessment earlier for high-risk patients, with possible deferral to year 5 when low risk. The newer AAO 2025 revision advises baseline fundus/OCT/FAF soon after starting and annual OCT plus wide-pattern FAF, with first-5-year deferral only without significant risk factors. Visual fields/multifocal ERG are confirmatory tools; assess both parafoveal and pericentral patterns. Suspected toxicity needs coordinated ophthalmology/prescriber action.

Follow disease response, actual-weight dose, organ function and interacting medicines. Periodically check blood counts and muscle strength/reflexes with prolonged therapy; assess cardiac tests, glucose, hemolysis or liver tests as clinically indicated. Report visual change, palpitations/fainting, blistering rash, jaundice, weakness or severe mood change promptly. Keep all tablets securely away from children; suspected overdose needs immediate expert care.

Current Plaquenil 200-mg sulfate tablets are white/off-white, film coated, unscored and marked PLAQUENIL in black ink. A 60-tablet bottle is NDC 59212-562-60; 100-tablet packages include NDC 59212-562-10 and -11. Verify the actual manufacturer and label for generics.

The selected product is a 200-mg hydroxychloroquine sulfate tablet, equivalent to 155 mg base, for oral use. Other strengths, Sovuna, generic scoring instructions and compounded liquid regimens are outside this specific product scope; the Plaquenil prohibition on dividing/crushing cannot be generalized without checking their labels.

Dispense in a tight, light-resistant container. The label specifies room-temperature storage up to 30°C, with excursions between 15°C and 30°C. Keep tablets intact and out of children’s reach; check expiry and the dispensed package.