Hyoscyamine


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Visceral spasms As base: 0.15-0.3 mg up to 4 times/day. As sulfate: Initial: 125-250 mcg 4 hrly or as needed. Max: 1.5 mg/24 hr. IV Block adverse muscarinic effects of anticholinesterase agents As sulfate: 0.2 mg IV for each 1 mg of neostigmine methylsulfate or the equivalent dose of physostigmine salicylate or pyridostigmine bromide given. Administer w/or a few mins before the anticholinesterase agent.IV/IM Organophosphorus poisoning As sulfate: 1-2 mg IV. Additional 1-mg doses may be given IM/IV every 3-10 mins until muscarinic signs and symptoms subside. IV/IM/SC Visceral spasms As sulfate: 0.25-0.5 mg 4 hrly. Pre-op medication As sulfate: 5 mcg/kg 30-60 mins before induction of anesth or at the time other pre-anesth medications are given.
Dosage Details
Intravenous
Block adverse muscarinic effects of anticholinesterase agents
Adult: As sulfate: 0.2 mg for each 1 mg of neostigmine methylsulfate or the equivalent dose of physostigmine salicylate or pyridostigmine bromide given. Administer concurrently with (but in a separate syringe) or a few minutes before the anticholinesterase agent. If there is bradycardia, administer before the anticholinesterase agent to increase the pulse rate to about 80 beats/min.

Oral
Visceral spasms
Adult: As base: 0.15-0.3 mg up to 4 times daily. As sulfate: Initially, 125-250 mcg, given orally or sublingually every 4 hr or as needed. Max dose: 1.5 mg/24 hr.
Child: As sulfate: <2 yr: Weighs about 2.3 kg: Approx 12.5 mcg; 3.4 kg: 16.7 mcg; 5 kg: 20.8 mcg; 7 kg: 25 mcg; 10 kg: 31.3-33.3 mcg; 15 kg: 45.8 mcg. Max dose/24 hr: 75, 100, 125, 150, 200 and 275 mcg, respectively. 2 to <12 yr: Weighs about 10 kg: Approx 31.3-33.3 mcg; 20 kg: 62.5 mcg; 40 kg: 93.8 mcg; 50 kg: 125 mcg. Max dose: 750 mcg/24 hr. ≥12 yr: Initially, 125-250 mcg. Max dose: 1.5 mg/24 hr. Doses may be repeated every 4 hr as needed.

Parenteral
Organophosphorus poisoning
Adult: As sulfate: 1-2 mg IV. Additional 1-mg doses may be given IM or IV every 3-10 min until muscarinic signs and symptoms subside and repeated if they reappear.

Parenteral
Visceral spasms
Adult: As sulfate: 0.25-0.5 mg IM or IV or SC every 4 hr.

Parenteral
Preoperative medication
Adult: As sulfate: 5 mcg/kg given IV, IM or SC 30-60 minutes prior to induction of anaesthesia or at the time other preanaesthetic medications are given.
Child: As sulfate: >2 yr: 5 mcg/kg given IV, IM or SC 30-60 min prior to induction of anaesthesia or at the time other preanaesthetic medications are given.
Contraindications
Glaucoma; obstructive uropathy; myasthenia gravis; obstructive GIT disease, paralytic ileus, intestinal atony of elderly or debilitated patients, severe ulcerative colitis, toxic megacolon; unstable CV status in acute haemorrhage, myocardial ischaemia; lactation.
Special Precautions
Heat prostration may occur in hot weather. Diarrhoea; psychosis; autonomic neuropathy, coronary heart disease, CHF, cardiac arrhythmias, prostatic hyperplasia, hyperthyroidism, hypertension, renal disease and hiatal hernia associated with reflux oesophagitis; childn with spastic paralysis. May precipitate glaucoma and/or markedly impair memory function in elderly. Pregnancy.
Adverse Reactions
Palpitations, tachycardia; ataxia, dizziness; urticaria; lactation suppression; bloating, constipation, dry mouth; impotence, urinary hesitancy, urinary retention; weakness; blurred vision, cycloplegia, increased ocular tension, mydriasis; allergic reactions; decreased sweating.
Overdosage
Symptoms: Dilated and unreactive pupils, blurred vision, hot and dry flushed skin, CNS stimulation, dry mucous membranes, dysphagia, foul breath, reduced or absent bowel sounds, urinary retention, tachycardia, hyperthermia, hypertension, and increased respiratory rate. Management: For life-threatening symptoms, give physostigmine 0.5-2 mg SC or IV slowly; repeat as necessary, up to total of 5 mg. Sulfate salt is dialysable.
Drug Interactions
Additive toxicity with amantadine, antihistamines, antimuscarinics, haloperidol, phenothiazines, TCAs and MAOIs. Decreased absorption with antacids.
Lab Interference
May interfere with the gastric secretion test.
Action
Description: Hyoscyamine is a tertiary amine antimuscarinic. It blocks the action of acetylcholine at parasympathetic sites in smooth muscle, secretory glands and the CNS. It increases cardiac output, dries secretions and antagonises histamine and serotonin.
Onset: 2-3 min.
Duration: 4-6 hr.
Pharmacokinetics:
Absorption: Well absorbed.
Distribution: Protein-binding: 50%.
Metabolism: Hepatic.
Excretion: Via urine; 3-5 hr (elimination half-life).
Storage
Store at controlled room temperature.
Disclaimer: This information is independently developed by MIMS based on Hyoscyamine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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