Side Effects of Plaquenil These drugs are generally well tolerated at doses used for malaria but may cause pruritis and exacerbate psoriasis

With frequent dosing, rarely reported adverse events include retinopathy and cardiac arrhythmias (QT prolongation specifically) in those with liver or kidney dysfunction. Exceeding recommended doses of chloroquine and hydroxychloroquine can lead to death, and fatal overdoses have been reported. Hydroxychloroquine is also FDA approved for use in rheumatoid arthritis and systemic lupus erythematosis. imidazole or macrolide antibiotics and in patients with underlying cardiac or liver diseases. It is hoped that with a better understanding of the arrhythmogenic mechanism of non-sedating antihistamines, one will be able to identify those at risk patients and prevent any cardiac on front page toxicity associated with antihistamines and ultimately death. An 85-year-old lady presented to our institution following multiple episodes of transient loss of consciousness.

Hydroxychloroquine cardiotoxicity presenting as a rapidly evolving biventricular cardiomyopathy: key diagnostic features and literature review

It has now been shown that the molecular target in human ventricle for the potassium channel blockade of antihistamine is HERG gene located in chromosome 7 that expresses the delayed rectifier IKr and appears to be involved in the congenital long QT syndrome. There is also a lack of information on the cardiac actions of newer non-sedating antihistamines.

Chronic toxicity should be considered when conduction disorders (bundle-branch block, AV block) or biventricular hypertrophy are diagnosed.

Many drugs prolong the QT interval and increase the risk of torsade de pointes.

Females, geriatric patients, patients with diabetes, thyroid disease, malnutrition, liver impairment, or those who drink alcohol to excess may also be at increased risk for QT prolongation.

If cardiotoxicity is suspected, prompt discontinuation of hydroxychloroquine may prevent life-threatening cardiac complications.

Using the administrative claims database of a national pharmaceutical benefit manager, we conducted a retrospective cohort study in 4, 825, 345 subjects aged 18 years or older. After identifying 50 drugs with QT-prolonging potential, and an additional 26 drugs that inhibit the metabolic clearance of QT-prolonging drugs, we measured the frequency of overlapping prescriptions for two or more of these drugs in the outpatient setting in 1999. Nearly 1. 1 million subjects (22. 8%) filled 4. 4 million prescriptions for QT-prolonging drugs. Of these, 103, 119 subjects (9. 4%) filled overlapping prescriptions for two or more of the drugs or for a QT-prolonging drug and another drug that inhibits its clearance; 7249 subjects (0. 7%) filled overlapping prescriptions for three or more of these drugs. Twenty-two percent of subjects who filled overlapping prescriptions were aged 65 or older; 74% were women. Females, geriatric patients, patients with diabetes, thyroid disease, malnutrition, liver impairment, or those who drink alcohol to excess may also be at increased risk for QT prolongation.

Chronic toxicity should be considered when conduction disorders (bundle-branch block, AV block) or biventricular hypertrophy are diagnosed. If cardiotoxicity is suspected, prompt discontinuation of hydroxychloroquine may prevent life-threatening cardiac complications. Many drugs prolong the QT interval and increase the risk of torsade de pointes. Concurrent use of two or more of these drugs can further increase the risk, but the prevalence of concurrent prescription of QT-prolonging drugs is not known. Concurrent prescription of QT-prolonging drugs is common in the outpatient setting, and antidepressants are involved in half of these cases. Large pharmaceutical claims databases are useful for detecting potentially harmful prescribing behaviors, but better clinical evidence on medication safety is needed before such a system can be implemented fully. Chloroquine and hydroxychloroquine are FDA-approved drugs used to prevent and treat certain types of malaria. They have a long elimination half-life of 30–45 days, allowing for weekly dosing when used in prevention of malaria, and a short 48-hour treatment course when used to treat malaria.