Product Information

Registration Status: Active

PROPYL TABLET 50mg is approved to be sold in Singapore with effective from 2001-08-10. It is marketed by JOYSON PTE LTD, with the registration number of SIN11695P.

This product contains Propylthiouracil 50mg in the form of TABLET. It is approved for ORAL use.

This product is manufactured by SRIPRASIT PHARMA CO LTD in THAILAND.

It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.



A thiourea antithyroid agent. Propythiouracil inhibits the synthesis of thyroxine and inhibits the peripheral conversion of throxine to tri-iodothyronine. It is used in the treatment of hyperthyroidism. (From Martindale, The Extra Pharmacopeoia, 30th ed, p534)


Used to manage hyperthyroidism which is due to an overactive thyroid gland (Grave's disease).

Mechanism of Action

Propylthiouracil binds to thyroid peroxidase and thereby inhibits the conversion of iodide to iodine. Thyroid peroxidase normally converts iodide to iodine (via hydrogen peroxide as a cofactor) and also catalyzes the incorporation of the resulting iodide molecule onto both the 3 and/or 5 positions of the phenol rings of tyrosines found in thyroglobulin. Thyroglobulin is degraded to produce thyroxine (T4) and tri-iodothyronine (T3), which are the main hormones produced by the thyroid gland. Therefore propylthiouracil effectively inhibits the production of new thyroid hormones.


Well absorbed following oral administration.


Oral, rat: LD50 = 1250 mg/kg.

Active Ingredient/Synonyms

2-Mercapto-6-propyl-4-pyrimidone | 2-Mercapto-6-propylpyrimid-4-one | 2-Thio-4-oxo-6-propyl-1,3-pyrimidine | 2-Thio-6-propyl-1,3-pyrimidin-4-one | 2,3-dihydro-6-Propyl-2-thioxo-4(1H)-pyrimidinone | 4-Propyl-2-thiouracil | 6-Propyl-2-thio-2,4(1H,3H)pyrimidinedione | 6-Propyl-2-thioxo-2,3-dihydropyrimidin-4(1H)-one | 6-Propylthiouracil | 6-Thio-4-propyluracil | Propiltiouracilo | Propylthiouracil | Propylthiouracile | Propylthiouracilum | Propylthiouracil |

Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.


  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank