Propylthiouracil

Absorption

Well absorbed following oral administration.

Toxicity

Oral, rat: LD50 = 1250 mg/kg.

Description

Propylthiouracil (PTU) is a thioamide antithyroid agent. It inhibits thyroid peroxidase activity in rat and monkey thyroid microsomes (IC₅₀s = 0.081 and 4.1 μM, respectively). PTU (30 mg/kg) increases thyroid weight and serum thyroid stimulating hormone levels and decreases serum 3,5,3''-triiodothyronine and thyroxine levels in rats. Sensitivity to the bitter taste of PTU is genetically mediated and is associated with increased sensitivity to other sweet and bitter compounds. Formulations containing propylthiouracil have been used in the treatment of Graves'' disease and hyperthyroidism.

Chemical properties

White Crystalline Powder

Chemical properties

White crystalline solid or powder. Odorless. Bitter taste.

The Uses of Propylthiouracil

Antihyperthyroid. Has been used to promote fattening. This substance is reasonably anticipated to be a human carcinogen

The Uses of Propylthiouracil

antibacterial

The Uses of Propylthiouracil

Antihyperthyroid. Has been used to promote fattening. This substance is reasonably anticipated to be a human carcinogen.

Indications

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

Background

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)

What are the applications of Application

6-Propyl-2-thiouracil is an inhibitor of DIO1

Definition

ChEBI: A pyrimidinethione consisting of uracil in which the 2-oxo group is substituted by a thio group and the hydrogen at position 6 is substituted by a propyl group.

General Description

Odorless white crystalline powder of starch-like appearance. Bitter taste. Saturated solution is neutral or slightly acid to litmus.

General Description

Propylthiouracil, 6-propyl-2-thiouracil (Propacil), is a stable, white, crystalline powderwith a bitter taste. It is slightly soluble in water but readilysoluble in alkaline solutions (salt formation).

Air & Water Reactions

Sensitive to light. May be sensitive to prolonged exposure to air. Insoluble in water.

Reactivity Profile

Propylthiouracil is incompatible with strong oxidizing agents, strong acids and strong bases. Forms complexes with divalent metals. Reacts with sulfhydryl-oxidizing agents . When reduced will produce hydrogen sulfide.

Hazard

Possible carcinogen.

Fire Hazard

Flash point data for Propylthiouracil are not available; however Propylthiouracil is probably combustible.

Biochem/physiol Actions

6-Propyl-2-thiouracil (6-PTU), a potential inhibitor of D1 iodothyronine deiodinase, is involved in the deiodination of iodothyronines. It is an uncompetitive inhibitor of iodothyronine substrates.

Mechanism of action

This drug has a pronounced thyrostatic effect and causes reduced thyroxine synthesis in the thyroid gland. It inhibits the process of iodination of thyroglobulin, reduces formation of the active form of iodine in the thyroid gland, and blocks the peroxidase system. Propylthiouracil is used for hyperthyrosis, thyrotoxic crises, and on thyrodectomia. Synonyms of this drug are propycil and tireostat.

Pharmacokinetics

Propylthiouracil is a thiourea antithyroid agent. Grave's disease is the most common cause of hyperthyroidism. It is an autoimmune disease where an individual's own antibodies attach to thyroid stimulating hormone receptors within cells of the thyroid gland and then trigger overproduction of thyroid hormone. The two thyroid hormones manufactured by the thyroid gland, thyroxine (T4) and triiodothyronine (T3), are formed by combining iodine and a protein called thyroglobulin with the assistance of an enzyme called peroxidase. PTU inhibits iodine and peroxidase from their normal interactions with thyroglobulin to form T4 and T3. This action decreases thyroid hormone production. PTU also interferes with the conversion of T4 to T3, and, since T3 is more potent than T4, this also reduces the activity of thyroid hormones. The actions and use of propylthiouracil are similar to those of methimazole.

Clinical Use

Propylthiouracil is useful in the treatment of hyperthyroidism.There is a delay in appearance of its effects because propylthiouracildoes not interfere with the activity of thyroid hormonesalready formed and stored in the thyroid gland. Thislag period may vary from several days to weeks, dependingon the condition of the patient. The need for three equallyspaced doses during a 24-hour period is often stressed, butevidence now indicates that a single daily dose is as effectiveas multiple daily doses in the treatment of most hyperthyroidpatients.

Safety Profile

Confirmed carcinogen with experimental carcinogenic, neoplastigenic, and tumorigenic data. Poison by intraperitoneal route. Moderately toxic by ingestion. Human systemic effects: agranulocytosis, hepatitis, jaundice. Human teratogenic effects by ingestion: developmental abnormalities of the endocrine system and changes in newborn viability. Human and experimental teratogenic and reproductive effects. Human mutation data reported. When heated to decomposition it emits very toxic fumes of SO, and NO,. See also MERCAPTANS.

Synthesis

Propylthiouracil, 6-propyl-2-thio-2,4-(1H,3H)-pyrimidindione (25.2.2), is synthesized by condensating ethyl butyroacetate with thiourea in the presence of sodium ethoxide.

Potential Exposure

Medication (antihyperthyroid; thyroid inhibitor) with human and veterinary applications.

Carcinogenicity

Propylthiouracil is reasonably anticipated to be a human carcinogenbased on sufficient evidence of carcinogenicity from studies in experimental animals.

Metabolism

Not Available

Metabolism

Propylthiouracil undergoes rapid first-pass metabolism in the liver, and is mainly excreted in the urine as the glucuronic acid conjugate, with very little excreted as unchanged drug.

Shipping

UN3249 Medicine, solid, toxic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Purification Methods

Purify propacil by recrystallisation from H2O (soluble in 900 parts at 20o, and 100 parts at 100o). UV, MeOH: max 277nm. [Anderson et al. J Am Chem Soc 67 2197 1945, Vanderhaegue Bull Soc Chim Belg 59 689 1950, Beilstein 24 III/IV 1333.]

Incompatibilities

This chemical is probably combustible; it’s dust may form explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanga- nates, perchlorates, chlorine, bromine, fluorine, etc.); con- tact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Forms complexes with divalent metals. Reacts with sulfhydryl-oxidizing agents . Sensitive to light and may be sensitive to air.

Waste Disposal

It is inappropriate and possi- bly dangerous to the environment to dispose of expired or waste pharmaceuticals by flushing them down the toilet or discarding to trash. Household quantities of expired or waste pharmaceuticals may be mixed with wet cat litter or coffee grounds, double-bagged in plastic, discard in trash. Larger quantities shall carefully take into consideration applicable DEA, EPA, and FDA regulations. If possible return the pharmaceutical to the manufacturer for proper disposal being careful to properly label and securely pack- age the material. Alternatively, the waste pharmaceutical shall be labeled, securely packaged and transported by a state licensed medical waste contractor to dispose by burial in a licensed hazardous or toxic waste landfill or incinerator.