Abstract:
Hyperthyroidism, a common problem, causes from excessive synthesis of thyroid hormone. There are 3 ways to cure this condition; by antithyroid drugs such as propylthiouracil (PTU) and methimazole (MMI), by radioactive iodine, and by surgery - thyroidectomy. Antithyroid drugs are usually effective in the treatment of hypethyroidism and thyroid storm, and they are the treatment of choice in thyroid storm. Emergent thyroidectomy may be impractical and highly dangerous in the mobid thyrotoxic pateints, and radioactive iodine does not provide rapid control of this disorder. At the present time, these antithyroid drugs are commercially available only as oral tablets. This renders therapy difficult in patients who are unable to take oral medication or through nasogastric tube, such as those already on antithyroid drug treatment who are postoperative and unable to take oral preparations for prolonged periods, or an unconscious patients. There were many successfully treated case reports about treatment hyperthyroid condition with the special condition by using PTU or MMI through rectal administration. This is a comparative study of plasma drug level of methimazole by oral and rectal administration. Six females and 1 male volunteers, between the age of 23 - 35, who were in healthy condition as judged by history, physical and laboratory examination, participated in the study. The volunteers, while fasting was received methimazole 30 mg. per rectum and oral route respectively. The rectal preparation consisted of a retention enema containing the contents of 30 mg. methimazole tablets suspended in 60 ml NSS. Study periods were separated in 2 weeks. Blood samples for methimazole were obtained at 0, 30, 60, 90, 120, 180, 240, 300, 360 minutes post drug administration. Plasma methimazole was determined by HPLC method. The drug was well tolerated by all subjects and all retention enemas were retained and not passed intact. Plasma methimazole level reached higher peak after rectal route in almost of subjects. There were no statistically significant differences in the plasma methimazole level between oral and rectal routes of drug administration at any time. (p>0.05) The variability of absorption between the oral and rectal routes is 3.432 Ug/ml. in a maximum difference in peak plasma level. (range 0.0008 - 3.432) This study suggests that the rectal administration of methimazole by retention enema can be a therapeutic option in the treatment of hyperthyroidism determined by plasma methimazole level in healthy volunteers between oral and rectal route. Such this alternative therapeutic route of administration is especially important in patients who cannot take oral medications, and the rectal methimazole at the same dosage should be effective in the control of hyperthyroidism.