Other drugs classified as disease-modifying anti-rheumatic drugs
HYDROXYCHLOROQUINE SULFATE
Indications and dose
Active rheumatoid arthritis (administered on expert advice),
Systemic and discoid lupus erythematosus (administered on expert advice),
Dermatological conditions caused or aggravated by sunlight (administered on expert advice)
By mouth
-
For
Adult
200–400 mg daily, daily maximum dose to be based on ideal body-weight; maximum 6.5 mg/kg per day.
Cautions
Acute porphyrias ; diabetes (may lower blood glucose); G6PD deficiency; maculopathy; may aggravate myasthenia gravis; may exacerbate psoriasis; neurological disorders (especially in those with a history of epilepsy—may lower seizure threshold); severe gastro-intestinal disorders
Cautions, further information
Monitoring for retinopathy
A review group convened by the Royal College of Ophthalmologists has updated guidelines on monitoring for chloroquine and hydroxychloroquine retinopathy (Hydroxychloroquine and Chloroquine Retinopathy: Recommendations on Monitoring 2020). Recent data have highlighted that hydroxychloroquine retinopathy is more common than previously reported.
Monitoring recommendations for hydroxychloroquine:
- All patients planning to be on long-term treatment should receive a baseline examination (including fundus photography and spectral domain optical coherence tomography) within 6–12 months of treatment initiation;
- Annual monitoring is recommended in all patients who have taken hydroxychloroquine for greater than 5 years;
- Annual monitoring may be commenced before 5 years of treatment if additional risk factors for retinal toxicity exist, such as concomitant tamoxifen therapy, impaired renal function (eGFR less than 60 mL/minute/1.73 m2) or high-dose therapy (greater than 5 mg/kg/day of hydroxychloroquine sulfate).
Interactions
Individual interactants:
Side-effects
Common or very common
Abdominal pain; appetite decreased; diarrhoea; emotional lability; headache; nausea; skin reactions; vision disorders; vomiting
Uncommon
Alopecia; corneal oedema; dizziness; eye disorders; hair colour changes; nervousness; neuromuscular dysfunction; retinopathy; seizure; tinnitus; vertigo
Frequency not known
Acute hepatic failure; agranulocytosis; anaemia; angioedema; bone marrow disorders; bronchospasm; cardiac conduction disorders; cardiomyopathy; hearing loss; hypoglycaemia; leucopenia; movement disorders; muscle weakness; myopathy; photosensitivity reaction; psychosis; reflexes absent; severe cutaneous adverse reactions (SCARs); thrombocytopenia; tremor; ventricular hypertrophy
Overdose
Hydroxychloroquine is very toxic in overdosage; overdosage is extremely hazardous and difficult to treat. Urgent advice from the National Poisons Information Service is essential. Life-threatening features include arrhythmias (which can have a very rapid onset) and convulsions (which can be intractable).
Pregnancy
It is not necessary to withdraw an antimalarial drug during pregnancy if the rheumatic disease is well controlled; however, the manufacturer of hydroxychloroquine advises avoiding use.
Breast feeding
Manufacturer advises use with caution—present in milk in small amounts. Specialist sources indicate risk of accumulation in infant due to long half-life; monitor infant for symptoms of uveitis e.g. eye redness or sensitivity to light.
Hepatic impairment
Manufacturer advises caution.
Dose adjustments
Manufacturer advises consider dose adjustment in severe impairment.
Renal impairment
Manufacturer advises caution.
Monitoring
Monitor plasma-hydroxychloroquine concentration in severe renal impairment.
Monitoring requirements
Monitoring of patient parameters
Manufacturer advises regular ophthalmological examination but the evidence of practical value is unsatisfactory (see Cautions, further information for advice of the Royal College of Ophthalmologists).
Prescribing and dispensing information
To avoid excessive dosage in obese patients, the dose of hydroxychloroquine should be calculated on the basis of ideal body-weight.
Medicinal forms
There can be variation in the licensing of different medicines containing the same drug.
Forms available from special-order manufacturers include: oral suspension, oral solution