Efficacy and Safety of Cholestyramine and Prednisolone as Adjunctive Therapy in Treatment of Overt Hyperthyroidism

Overview

Hyperthyroidism is the second most common endocrine disorder in the world with Graves' disease being the commonest. Anti thyroid drugs including methimazole, carbimazole, and propylthiouracil are effective treatments but take in most cases between 6 to 8 weeks to achieve euthyroidism. This study aim to assess the efficacy of cholestyramine and prednisolone as adjunctive treatment to standard treatment in patients with overt hyperthyroidism in 4 weeks.

Hyperthyroidism is the second most common endocrine disorder in the world with an estimate prevalence rate of 0.5-1.3% with Graves' disease being the commonest cause. Uncontrolled hyperthyroidism results in increase cardiovascular morbidity and mortality primarily due to heart failure and thromboembolism. Therefore treatment is essential to restore a euthyroid state in order to reverse the cardiovascular complications. Anti thyroid drugs (ATDs) including methimazole, carbimazole, and propylthiouracil are effective treatments that inhibit thyroid hormone synthesis, and have clinically important immunosuppressive effects including reducing serum antithyrotropin receptor antibody (TRAb) concentration with time but take in most cases between 6 to 8 weeks to achieve euthyroidism. Therefore there may be a role for adjunctive treatment added on to ATDs. It may be situations where adjunctive treatment is required to alleviate symptoms and restore euthyroidism rapidly such as before surgery or radioactive iodine treatment or in vulnerable groups such as the elderly or those with serious thyrotoxic complications. This study aim to assess the efficacy of cholestyramine and prednisolone as adjunctive treatment to standard treatment in patients with overt hyperthyroidism in 4 weeks. Cholestyramine is an anion exchange resin that binds thyroxine (T4) in the intestine resulting in fecal excretion of T4 thus reducing the enterohepatic circulation and absorption in hyperthyroidism. Steroids have been shown to be effective in controlling hyperthyroidism by inhibiting the conversion of thyroxine to triiodothyronine peripherally and also blocks the release of thyroxine from the thyroid gland. It may also have the potential to suppress the immune response and hence decrease stimulation of the thyroid gland in Graves. 135 patients with moderate to severe uncontrolled overt hyperthyroid patients secondary to Graves disease will be randomized into 3 groups. Group 1 patients will be treated with cholestyramine 4g twice a day plus carbimazole and propanolol for 4 weeks. Group 2 patients will be treated with prednisolone 30 mg daily for week 1, 20 mg daily for week 2, 10 mg daily for week 3 and 5 mg daily for week 4 plus carbimazole and propanolol for 4 weeks. Group 3 patients will be treated with carbimazole 30 mg daily and propanolol 40 mg bd for 4 weeks. Patients will have their clinical status (weight, blood pressure, pulse rate) measured at baseline along with a TRAb level and Free Triiodotyronine (T3), Free T4 and Thyroid stimulating hormone (TSH) levels. They will be evaluated at week 2 and week 4 of intervention period and have their clinical status (weight, blood pressure, pulse rate) and laboratory (Free T3, Free T4, TSH, Potassium, Fasting/random blood glucose) measured. Adverse events will be monitored at week 2, 4, and 6.

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