Plaquenil Special Precautions

Retinopathy: All patients should have an ophthalmological examination before treatment with hydroxychloroquine sulfate (Plaquenil) is initiated. Thereafter, ophthalmological examinations must be repeated at least every 12 months.
Retinal toxicity is largely dose-related. The risk of retinal damage is small with daily doses of up to 6.5 mg/kg body weight. Exceeding the recommended dose sharply increases the risk of retinal toxicity.
The examination should include testing visual acuity and colour vision, careful ophthalmoscopy, fundoscopy and central visual field testing with a red target.
This examination should be more frequent and adapted to the patient in the following situations: daily dosage exceeds 6.5 mg/kg lean body weight. Absolute body weight used as a guide to dosage could result in an overdosage in the obese; renal insufficiency; visual acuity below 6/8; age above 65 years; cumulative dose more than 200 g.
Hydroxychloroquine sulfate (Plaquenil) should be discontinued immediately in any patient who develops a pigmentary abnormality, visual field defect or any other abnormalities not explained by difficulty in accommodation (see also Adverse Reactions). Patients should continue to be observed as retinal changes and visual disturbances may progress even after cessation of therapy (see also Adverse Reactions).
Concomitant use of hydroxychloroquine with medicines known to induce retinal toxicity, such as tamoxifen, is not recommended.
Hypoglycaemia: Hydroxychloroquine has been shown to cause severe hypoglycemia including loss of consciousness that could be life threatening in patients treated with and without antidiabetic medications. Patients treated with Hydroxychloroquine should be warned about the risk of hypoglycemia and the associated clinical signs and symptoms. Patients presenting with clinical symptoms suggestive of hypoglycemia during treatment with Hydroxychloroquine should have their blood glucose level checked and treatment reviewed as necessary.
QT interval prolongation: Hydroxychloroquine has potential to prolong the QTc interval in patients with specific risks factors.
Hydroxychloroquine should be used with caution in patients with congenital or documented acquired QT prolongation and/or known risk factors for prolongation of the QT interval such as: cardiac disease, e.g., heart failure, myocardial infarction; proarrhythmic conditions, e.g., bradycardia (<50 bpm); a history of ventricular dysrhythmias; uncorrected hypokalemia and/or hypomagnesemia; during concomitant administration with QT interval prolonging agents (see Interactions) as this may lead to an increased risk for ventricular arrhythmias.
The magnitude of QT prolongation may increase with increasing concentrations of the medicine. Therefore, the recommended dose should not be exceeded (see also Interactions and Adverse Reactions).
If signs of cardiac arrhythmia occur during treatment with hydroxychloroquine, treatment should be stopped and an ECG should be performed.
Chronic cardiac toxicity: Cases of cardiomyopathy resulting in cardiac failure, in some cases with fatal outcome, have been reported in patients treated with Hydroxychloroquine sulfate (Plaquenil) (see Adverse Reactions and Overdosage). Clinical monitoring for signs and symptoms of cardiomyopathy is advised, and hydroxychloroquine sulfate (Plaquenil) should be discontinued if cardiomyopathy develops.
Chronic toxicity should be considered when conduction disorders (bundle branch block-/atrio-ventricular heart block) as well as biventricular hypertrophy are diagnosed (see Adverse Reactions).
Other monitoring on long-term treatments: Patients on long term therapy should have periodic full blood counts, and hydroxychloroquine should be discontinued if abnormalities develop (see Adverse Reactions).
All patients on long-term therapy should undergo periodic examination of skeletal muscle function and tendon reflexes. If weakness occurs, hydroxychloroquine should be withdrawn (see Adverse Reactions).
Potential carcinogenic risk: Animal carcinogenicity data are only available for one species for the parent medicine chloroquine and this study was negative (see Pharmacology: Toxicology: Preclinical safety data under Actions). In humans, there are insufficient data to rule out an increased risk of cancer in patients receiving-long term treatment.
Suicidal behavior and psychiatric disorders: Suicidal behaviour and psychiatric disorders have been reported in some patients treated with Hydroxychloroquine (see Adverse Reactions). Psychiatric side effects typically occur within the first month after the start of treatment with hydroxychloroquine and have been reported also in patients with no prior history of psychiatric disorders. Patients should be advised to seek medical advice promptly if they experience psychiatric symptoms during treatment.
Extrapyramidal disorders: Extrapyramidal disorders may occur with hydroxychloroquine sulfate (Plaquenil) (see Adverse Reactions).
Other precautions: Hydroxychloroquine sulfate (Plaquenil) should be used with caution in patients taking medicines which may cause adverse ocular or skin reactions. Caution should also be applied when it is used in the following: patients with hepatic or renal disease, and in those taking medicines known to affect those organs. Estimation of plasma hydroxychloroquine levels should be undertaken in patients with severely compromised renal or hepatic function, and dosage adjusted accordingly; patients with severe gastrointestinal, neurological, or blood disorders.
Caution is also advised in patients with a sensitivity to quinine, those with glucose-6-phosphate dehydrogenase deficiency, those with porphyria cutanea tarda which can be exacerbated by hydroxychloroquine, and in patients with psoriasis since it appears to increase the risk of skin reactions.
Small children are particularly sensitive to the toxic effects of 4-aminoquinolines therefore patients should be warned to keep hydroxychloroquine sulfate (Plaquenil) out of reach of children.
Plaquenil contains lactose: Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this medicine.
Malaria: Hydroxychloroquine is not effective against chloroquine-resistant strains of P. falciparum, and is not active against the exo-erythrocytic forms of P. vivax, P. ovale and P. malariae and therefore will neither prevent infection due to these organisms when given prophylactically, nor prevent relapse of infection due to these organisms.
Effects on ability to drive and use machines: Impaired visual accommodation soon after the start of treatment, which can cause blurring of vision, has been reported and patients should be warned regarding driving or operating machinery. If the condition is not self-limiting it will resolve on reducing the dose or stopping treatment.