Zanika Special Precautions

General: The occurrence of retinopathy is very uncommon if the recommended daily dose is not exceeded. The administration of doses in excess of the recommended maximum is likely to increase the risk of retinopathy, and accelerate its onset.
All patients should have an ophthalmological examination before initiating treatment with Zanika. Thereafter, ophthalmological examinations must be at least every 12 months. The examination should include testing visual activity, careful ophthalmoscopy, fundoscopy, central visual field testing with a red target, and colour vision. 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 should be discontinued immediately in any patient who develops a pigmentary abnormality, visual field defect, or any other explainable by difficulty in accommodation or presence of corneal opacities. Patients should continue to be observed for possible progression of the changes. Patients should be advised to stop taking the drug immediately and seek the advice of their prescribing doctor if any disturbances of vision are noted, including abnormal colour vision. Cases of cardiomyopathy resulting in cardiac failure, in some cases with fatal outcome, reported in patients treated with Zanika. Clinical monitoring for signs and symptoms of cardiomyopathy is advised and Zanika 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. Hydroxychloroquine sulfate 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 drugs 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.
Although the risk of bone marrow depression is low, periodic blood counts are advisable as anaemia, aplastic anaemia, agranulocytosis, a decrease in white blood cells, and thrombocytopenia have been reported. Zanika should be discontinued if abnormalities develop. 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 sulfate and in the patients with psoriasis since it appears to increase the risk of skin reactions. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine. Small children are particularly sensitive to the toxic effects of 4-aminoquinolines. Therefore, patients should be warned to keep Hydroxychloroquine Sulfate out of the reach of the reach of children. All patients on long-term therapy should undergo periodic examination of skeletal muscle function reflexes. If weakness occurs, the drug should be withdrawn. Hydroxychloroquine has been shown to cause severe hypoglycaemia including loss of consciousness that could be life threatening in patients treated with and without antidiabetic. Patients treated with hydroxychloroquine should be warned about the risk of hypoglycaemia and the associated clinical signs and symptoms. Patients presenting with clinical symptoms suggestive of hypoglycaemia during treatment with hydroxychloroquine should have their blood glucose level checked and treatment reviewed as necessary. Extrapyramidal disorders may occur with Hydroxychloroquine sulfate.
Information for Patients: Patients should be informed of the early signs and symptoms of toxicity such as rash, visual changes. Patients must see their physicians promptly in case of the appearance of these or of any unusual effects. Periodic laboratory tests may be recommended in some patients.
Patients should be fully informed of the potential risks of the use of hydroxychloroquine sulfate, especially in pregnancy and in children.
Carcinogenesis, mutagenesis, impairment of fertility: Long-term studies in animals have not been conducted to evaluate the carcinogenic potential of hydroxychloroquine sulfate.
The mutagenic potential of hydroxychloroquine sulfate was not evaluated. However, chloroquine has been shown to be a catalytic inhibitor of DNA repair enzymes (topoisomerase II) and to produce weak genotoxic effects through this mode of action.