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HALYCIL is a brand name for Propylthiouracil, supplied as a tablet. The medicine, its uses, side effects and dosage are the same regardless of brand.
Used for: HALYCIL™ (propylthiouracil tablets) is indicated: For the medical management of hyperthyroidism. In conjunction with radioiodine to hasten recovery while awaiting the effects of radiation. For the control of thyrotoxicosis prior to surgery. In the management of a thyroid storm in addition to other therapeutic…
Verbatim from this product's HC label. Tap a section to expand.
1 Dosing Considerations Treatment with HALYCIL should be individualized, according to the severity of symptoms and signs of hyperthyroidism and response to therapy. Usually after one or 2 weeks, but certainly after 3 weeks of therapy, objective signs of clinical improvement should be seen.
Delayed responses are sometimes noted when the thyroid is unusually large and when iodine in any form has previously been given. The course of therapy may last from 6 months to 3 years. Usually within 1 to 2 years, a prolonged remission in 50% of the cases can be expected.
When remission is observed, HALYCIL should be withdrawn over a period of 1-2 months under close supervision. 2 Recommended Dose and Dosage Adjustment Adults (≥18 years of age): The recommended initial dose is 50-100 mg (1 to 2 tablets of HALYCIL) every 8 hours, with increases as necessary up to a maximum of 500 mg/day.
In some cases, initial doses as high as 900 mg/day may be required. When doses larger than 300 mg/day of HALYCIL are needed, the drug should be administered every 4 to 6 hours. The patient should be examined regularly by the physician and the dose of HALYCIL adjusted until the patient is euthyroid (usually after 6-8 weeks).
At this stage, the dose should be reduced by 1/3 every 4-6 weeks to a maintenance dosage of one tablet of HALYCIL 2 or 3 times daily, administered at regular intervals.
Geriatric (>65 years of age):
Evidence from clinical studies and experience suggests that use in the geriatric population is associated with no differences in safety or effectiveness. Dose selection for an elderly patient should be cautious reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Pediatric (<18 years of age):
Health Canada has not authorized an indication for pediatric use.
Hepatic impairment:
No clinical studies have been performed with HALYCIL in patients with hepatic insufficiency. Since liver toxicity is associated with the use of propylthiouracil, caution is warranted in these patients. The dose should be kept as low as possible.
Peri-Operative Considerations When HALYCIL is administered pre-operatively, iodine, in the form of a strong iodine solution (Lugol’s solution or potassium iodide solution) should be given concomitantly for 7 -10 days prior to surgery.
The rationale for this is to reduce the vascularity and fragility of the thyroid gland. Renal HALYCIL should be used with caution in patients with renal impairment. 1 Pregnant Women Fertility Hyperthyroidism can cause a marked reduction in sperm count resulting in infertility.
Treatment with HALYCIL may result in normalisation in sperm count once the thyroid function is controlled. Hyperthyroidism can cause a reduction in fertility. Treatment with HALYCIL can result in rapid normalisation in fertility once the thyroid function is controlled.
Women of childbearing potential should use effective methods of contraception during HALYCIL therapy and should be informed about the potential risks of HALYCIL use during pregnancy. 1 Pregnant Women below. Respiratory In view of the fact that hypothyroid patients seem to have poor adrenergic nervous function, HALYCIL should be used with caution in patients with asthma.
Skin HALYCIL should be discontinued immediately at the appearance of a skin rash, as the rash may be, in some instances, followed by dermatological reactions/hypersensitivity syndrome . 1 Pregnant Women Hyperthyroidism in pregnant women should be adequately treated to prevent serious maternal and fetal complications.
Individual benefit/risk assessment is necessary before treatment with HALYCIL during pregnancy. If HALYCIL is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be warned of the potential hazard to the moth er and fetus of liver damage.
HALYCIL can be used prior to conception and in the first trimester of pregnancy where clinically appropriate due to the higher risk of congenital abnormalities with methimazole during fetal organogenesis in the first trimester. After the first trimester of pregnancy, the use of an alternative antithyroid medication may be advisable given the potential for maternal hepatotoxicity from HALYCIL.
Severe liver injury and acute liver failure, in some cases fatal, have been reported in patients treated with propylthiouracil. These reports of hepatic reactions include cases requiring liver transplantation in adult and pediatric patients.
1 Dosing Considerations Treatment with HALYCIL should be individualized, according to the severity of symptoms and signs of hyperthyroidism and response to therapy. Usually after one or 2 weeks, but certainly after 3 weeks of therapy, objective signs of clinical improvement should be seen.
Delayed responses are sometimes noted when the thyroid is unusually large and when iodine in any form has previously been given. The course of therapy may last from 6 months to 3 years. Usually within 1 to 2 years, a prolonged remission in 50% of the cases can be expected.
When remission is observed, HALYCIL should be withdrawn over a period of 1-2 months under close supervision. 2 Recommended Dose and Dosage Adjustment Adults (≥18 years of age): The recommended initial dose is 50-100 mg (1 to 2 tablets of HALYCIL) every 8 hours, with increases as necessary up to a maximum of 500 mg/day.
In some cases, initial doses as high as 900 mg/day may be required. When doses larger than 300 mg/day of HALYCIL are needed, the drug should be administered every 4 to 6 hours. The patient should be examined regularly by the physician and the dose of HALYCIL adjusted until the patient is euthyroid (usually after 6-8 weeks).
At this stage, the dose should be reduced by 1/3 every 4-6 weeks to a maintenance dosage of one tablet of HALYCIL 2 or 3 times daily, administered at regular intervals.
Geriatric (>65 years of age):
Evidence from clinical studies and experience suggests that use in the geriatric population is associated with no differences in safety or effectiveness. Dose selection for an elderly patient should be cautious reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
HALYCIL is contraindicated in patients who are hypersensitive to this drug, related thioamide derivatives or to any ingredient in the formulation, including any non-medicinal ingredient, or component of the container. For a complete listing, see 6 DOSAGE FORMS, STRENGTHS, COMPOSITION AND PACKAGING.
HALYCIL is contraindicated in breast-feeding women.
Not medical advice. Always read the patient information leaflet and follow your prescriber or pharmacist.
Other brands of Propylthiouracil in Canada.
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Renal impairment:
No clinical studies have been performed with HALYCIL in patients with renal impairment. M.
Bennett et al1:
Glomerular Filtration Rate (creatinine clearance) 10-50 mL/min <10 mL/min Reduce dose by 25% of the usual maintenance dose 50% of the usual maintenance dose 1. Bennett WM et al. Guidelines for drug therapy in renal failure. Ann Intern Med 1977; 86:754-83.
4 Administration HALYCIL can be taken with or without food. Patients should be instructed to swallow tablets whole and not to chew, split, or crush tablets. Patients should not ingest if tablets are broken, cracked, or otherwise not intact.
HALYCIL should be taken at the same time each day. 5 Missed Dose Advise patients to not double a dose to make up for a missed dose. When a dose is missed, HALYCIL should be taken as soon as the missed dose is noted. However, if the next scheduled dose is close, the patient should wait and take the next scheduled dose; the missed dose should not be taken.
HALYCIL should be administered during pregnancy at the lowest effective dose without additional administration of thyroid hormones. Close maternal, fetal and neonatal monitoring is recommended, with adjustment of HALYCIL as necessary.
HALYCIL, used judiciously, is an effective drug for the treatment of hyperthyroidism in pregnant women. However, the drug readily crosses the placental barrier where it can induce goiter and hypothyroidism in the developing fetus. Rare cases of congenital anomalies have been observed post-marketing.
5 Post-Market Adverse Reactions Product Monograph Master Template Template date: September 2020 HALYCIL™ (propylthiouracil) Page 10 of 22 Epidemiological studies provide conflicting results regarding the risk of congenital malformations.
2 Breast-feeding HALYCIL is excreted in breast milk and is contraindicated in nursing mothers. 3 Pediatrics Pediatrics (<18 years of age): No data are available to Health Canada; therefore, Health Canada has not authorized an indication for pediatric use.
4 Geriatrics Geriatrics (>65 years of age): Evidence from clinical studies and experience suggests that use in the geriatric population is associated with no differences in safety or effectiveness. 1 Adverse Reaction Overview The most serious adverse reactions associated with HALYCIL are agranulocytosis, hepatotoxicity and rarely, systemic vasculitis.
Recovery is often possible following immediate cessation of the drug. Inhibition of hemopoiesis (agranulocytosis, granulocytopenia, leucopenia, thrombocytopenia) is the most serious side effect. 5%. It usually develops in the first few months of therapy, is dose-related and is reversible on rapid withdrawal of the drug.
Severe adverse reactions include liver injury presenting as hepatitis, liver failure necessitating liver transplantation or resulting in death. See 7 WARNINGS AND PRECAUTIONS Hepatocellular necrosis and fulminant hepatic failure have been reported in patients treated with HALYCIL.
Typically, these reactions occur within the first two months of HALYCIL treatment. Injury is reversible upon discontinuation of HALYCIL although encephalopathy and/or substantial hepatic necrosis have been reported. 2% in patients treated with HALYCIL.
HALYCIL-induced hepatotoxicity is not dose-related and is thought to be idiosyncratic with an autoimmune component.
Blood and Lymphatic System:
Reversible leucopenia, agranulocytosis, thrombocytopenia, leucopenia aplastic anemia, pancytopenia; a rare complication of therapy is a tendency to hemorrhage associate with hypoprothrombinemia which may be controlled by the administration of vitamin K1.
Ear and Labyrinth Disorders:
Hearing impairment may occur with HALYCIL. The impairment usually becomes less marked after withdrawal of the drug.
Gastrointestinal Disorders:
Nausea, gastrointestinal disturbances, taste perversion, rarely vomiting.
General Disorders and Administration Site Conditions:
Fever.
Product Monograph Master Template Template date:
September 2020 HALYCIL™ (propylthiouracil) Page 11 of 22 Hepatic Function: Jaundice (usually cholestatic), hepatic necrosis (sometimes with fatal consequences), encephalopathy, asymptomatic liver function test abnormalities (increased serum bilirubin, alanine transaminase and/or alkaline phosphatase concentrations), which are reversible on dose reduction or […]
Pediatric (<18 years of age):
Health Canada has not authorized an indication for pediatric use.
Hepatic impairment:
No clinical studies have been performed with HALYCIL in patients with hepatic insufficiency. Since liver toxicity is associated with the use of propylthiouracil, caution is warranted in these patients. The dose should be kept as low as possible.
Renal impairment:
No clinical studies have been performed with HALYCIL in patients with renal impairment. M.
Bennett et al1:
Glomerular Filtration Rate (creatinine clearance) 10-50 mL/min <10 mL/min Reduce dose by 25% of the usual maintenance dose 50% of the usual maintenance dose 1. Bennett WM et al. Guidelines for drug therapy in renal failure. Ann Intern Med 1977; 86:754-83.
4 Administration HALYCIL can be taken with or without food. Patients should be instructed to swallow tablets whole and not to chew, split, or crush tablets. Patients should not ingest if tablets are broken, cracked, or otherwise not intact.
HALYCIL should be taken at the same time each day. 5 Missed Dose Advise patients to not double a dose to make up for a missed dose. When a dose is missed, HALYCIL should be taken as soon as the missed dose is noted. However, if the next scheduled dose is close, the patient should wait and take the next scheduled dose; the missed dose should not be taken.
5 OVERDOSAGE Agranulocytosis is the most serious adverse effect resulting from overdose and/or prolonged administration. Overdosage can result in enlargement of the thyroid gland, with signs and symptoms of hypothyroidism. This can be readily reversed by reducing or even temporarily withdrawing medication.
Thyroxine replacement therapy, until the patient becomes euthyroid, may be indicated. Overdose may manifest as vomiting, epigastric distress, headache, fever, arthralgia, pruritis and pancytopenia. Overdosage in pregnant women may result in congenital goiter and hypothyroidism in the fetus.
The newborn child should be examined carefully for signs of hypothyroidism and immediate thyroid therapy should be instituted if hypothyroidism is confirmed. The treatment of HALYCIL overdose should aim to minimise the amount of drug absorbed in the circulation.
A full blood analysis should be considered because of the risk of haematological complications and appropriate therapy given if bone marrow depression develops. Hemorrhage may be controlled by the administration of vitamin K1 and the dosage of HALYCIL should be reduced.
There is no specific antidote for propylthiouracil. For management of a suspected drug overdose, contact your regional poison control centre. 5 mm by 3 mm. HALYCIL is supplied in bottles of 100 tablets or blister packs of 56 tablets. 7 WARNINGS AND PRECAUTIONS Please see 3 SERIOUS WARNINGS AND PRECAUTIONS BOX General HALYCIL should be reserved for patients who cannot tolerate methimazole and in whom radioactive iodine therapy or surgery are not appropriate treatments for the management of hyperthyroidism.
The vascularity and size of the thyroid gland may increase during treatment with HALYCIL. This suggests over treatment and indicates the need for […]