Hyoscyamine

Hyoscyamine is a Gastrointestinal drug belonging to an Anticholinergic agent.

Hyoscyamine is an anticholinergic indicated to treat functional gastrointestinal disorders, biliary and renal colic and acute rhinitis.

Hyoscyamine is well and completely absorbed from the gastrointestinal tract. The Time taken to reach peak plasma concentrations is approximately 4 hours (extended-release tablet). Hyoscyamine is distributed throughout the body, crosses the placenta and blood-brain barrier; enters breastmilk (in small amounts). The plasma protein binding is approximately 50%. Hyoscyamine metabolized in the liver, partly hydrolyzed to tropic acid, tropine and hyoscyamine glucuronide. It is excreted mainly via urine (as an unchanged drug within the 1st 12 hours).

Hyoscyamine shows side effects like Drowsiness, dizziness or lightheadedness, headache, blurred vision, flushing (feeling of warmth), dry mouth, constipation, difficulty urinating, increased sensitivity to light.

Hyoscyamine is available in the form of Oral Tablet, Oral capsules, Injectable solutions and Oral solutions.

Hyoscyamine is available in India, the US, Germany, Canada, France, Russia, Malaysia, Japan, China, and Australia.

Hyoscyamine belongs to the Anticholinergic agent and acts as a Gastrointestinal drug.

Hyoscyamine competitively and non-selectively antagonizes muscarinic receptors in the smooth muscle, cardiac muscle, Sinoatrial node, atrioventricular node, exocrine nodes, gastrointestinal tract, and respiratory tract. Antagonism of muscarinic M1, M4, and M5 receptors in the central nervous system leads to cognitive impairment; antagonism of M2 in the sinoatrial and atrioventricular nodes leads to increases in heart rate and atrial contractility; and antagonism of M3 in smooth muscle results in reduced peristalsis, bladder contraction, salivary secretions, gastric secretions, bronchial secretions, sweating, increased bronchodilation, mydriasis, and cycloplegia.

The Onset of action of Hyoscyamine is about 2-3 minutes.

The Duration of action of Hyoscyamine is approximately 4-6 hours (regular release) and 8-12 hours (extended release).

The Data of Tmax of Hyoscyamine is not readily available.

Hyoscyamine is available in the form of Oral Tablet, Oral capsules, Injectable solutions and Oral solution.

Hyoscyamine Tablet, capsule and solution are taken orally, while an injectable solution is given via intravenous, intramuscular, and subcutaneous routes.

Hyoscyamine is an alkaloid derivative used to treat various gastrointestinal disorders, including spasms such as peptic ulcer, irritable bowel syndrome, etc. It is also used to relieve tremors in patients with parkinsonism.

Hyoscyamine is a Gastrointestinal drug belonging to an Anticholinergic agent.

Hyoscyamine blocks the action of acetylcholine at parasympathetic sites in the smooth muscle, secretory glands, and the CNS; it increases cardiac output, dries secretions, antagonizes histamine and serotonin.

Hyoscyamine is approved for use in the following clinical indications

Adult indication

• GI disorders

Pediatric indication

• Preanesthesia
• Reduce drug-induced bradycardia during surgery
• Reversal of neuromuscular blockage

Adult indication

• GI disorders

Oral

Immediate release: 0.125 to 0.25 mg every 4 to 8 hours or as needed; maximum: 1.5 mg/day.

Extended-release: 0.375 to 0.75 mg every 12 hours or 0.375 mg every 8 hours; maximum: 1.5 mg/day.

IM, IV, Subcutaneous: 0.25 to 0.5 mg; may repeat as needed up to 4 times daily, at 4-hour intervals.

Pediatric indication

• Preanesthesia

Children >2 years and Adolescents: IM, IV, Subcutaneous: 5 mcg/kg administered 30 to 60 minutes before induction of anesthesia or at the Time preoperative opioids or sedatives are administered.

• Reduce drug-induced bradycardia during surgery

Children >2 years and Adolescents: IV: 0.125 mg; repeat as needed.

• Reversal of neuromuscular blockage

Children >2 years and Adolescents: IV, IM, Subcutaneous: 0.2 mg for every 1 mg neostigmine (or physostigmine/pyridostigmine equivalent).

Hyoscyamine is available in various strengths as 0.5 mg/mL; 0.125 mg; 0.375 mg; 0.125 mg/5 mL; 0.125 mg/mL; 0.15 mg; 0.375 mg dual-release; sulfate; hydrobromide.

Hyoscyamine is available in the form of Oral Tablet, Oral capsule, Injectable solution and Oral solution.

Hyoscyamine is contraindicated in patients with

• Glaucoma
• Obstructive uropathy (for example, bladder neck obstruction due to prostatic hypertrophy)
• Obstructive disease of the gastrointestinal tract (as in achalasia, pyloro duodenal stenosis)
• Paralytic ileus, intestinal atony of elderly or debilitated patients; unstable cardiovascular status in acute hemorrhage
• Severe ulcerative colitis
• Toxic megacolon complicating ulcerative colitis
• Myasthenia gravis.

• CNS effects: May cause Drowsiness and/or blurred vision, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (e.g., operating machinery or driving).
• Diarrhea: This may be a sign of incomplete intestinal obstruction, especially in patients with ileostomy or colostomy; treatment should be discontinued if this occurs.
• Heat prostration: This may occur in the presence of increased environmental temperature; use caution in hot weather and/or exercise.
• Psychosis: Has been reported in patients with an extreme sensitivity to anticholinergic effects; usually resolves within 12-48 hours after discontinuation.
• Cardiovascular disease: Use with caution in patients with coronary artery disease, tachyarrhythmias, heart failure, or hypertension; evaluate tachycardia prior to administration. Use is contraindicated in patients with unstable cardiovascular status or myocardial ischemia.
• Hiatal hernia: Use with caution in patients with hiatal hernia with reflux esophagitis.
• Hyperthyroidism: Use with caution in patients with hyperthyroidism.
• Neuropathy: Use with caution in patients with autonomic neuropathy.
• Prostatic hyperplasia: Use with caution in patients with prostatic hyperplasia.

Consumption of alcohol is not recommended while receiving this medicine as it may increase the risk of dizziness.

Hyoscyamine is excreted in human milk. Caution should be exercised when it is administered to a nursing woman.

Pregnancy Category C

Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

Common Adverse effects

• Flushing, palpitations, tachycardia, Amnesia (short-term), ataxia, confusion (more common in elderly), dizziness, Drowsiness, excitement (more common in elderly), fatigue, hallucination, headache, insomnia, nervousness, psychosis, speech disturbance, Hypohidrosis, urticaria, Abdominal pain, ageusia, bloating, constipation, diarrhea, dysgeusia, dysphagia, heartburn, nausea, vomiting, xerostomia, Decreased lactation, impotence, urinary hesitancy, urinary retention, Hypersensitivity reaction, Weakness, Blurred vision, cycloplegia, increased intraocular pressure, mydriasis, Fever.

• Additive adverse effects resulting from cholinergic blockade may occur when Hyoscyamine is administered concomitantly with other antimuscarinics, amantadine, haloperidol, phenothiazines, monoamine oxidase (MAO) inhibitors, tricyclic antidepressants or some antihistamines.

• Antacids may interfere with the absorption of Hyoscyamine. Administer Hyoscyamine before meals, antacids after meals.

The common side effect of Hyoscyamine include the following

Common

• Drowsiness, Dizziness or lightheadedness, Headache, Blurred vision, Flushing (feeling of warmth), Dry mouth, Constipation, Difficulty urinating, Increased sensitivity to light.

Rare

• Diarrhea, skin rash, eye pain, fast or irregular heartbeat.

• Pregnancy

Pregnancy Category C

Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

• Nursing Mothers

Hyoscyamine is excreted in human milk. Caution should be taken when it is administered to a nursing woman.

• Pediatric Use

Information is not available.

• Geriatric Use

Reported clinical experience has not identified differences in safety between patients aged 65 and over and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

Symptoms: Headache, vomiting, nausea, dilated pupils, blurred vision, dizziness, dryness of the mouth, hot dry skin, difficulty swallowing, and CNS stimulation.

Management: Symptomatic treatment. Perform gastric lavage immediately. Administer physostigmine 0.5-2 mg IV and may repeat as necessary up to a total of 5 mg. May use tepid water sponge bath and hypothermic blanket to treat fever. In case of excitement to a degree which demands attention, administer Na thiopental 2% solution via slow IV injection or chloral hydrate 2% solution (100-200 mL) via rectal infusion. Initiate and maintain artificial respiration, in case of curare-like effect progressing to respiratory muscles paralysis, until effective respiratory action returns.

Pharmacodynamic

Hyoscyamine is used as an antimuscarinic agent in several treatments and therapies. Hyoscyamine has a short duration of action as it may need to be given multiple times per day. Patients should be counselled regarding the risks and signs of anticholinergic toxicity.

Pharmacokinetics

• Absorption

Hyoscyamine well and completely absorbed from the gastrointestinal tract. The Time take to reach peak plasma concentrations is approximately 4 hours (extended release tablet).

• Distribution

Hyoscyamine is distributed throughout the body and it crosses the placenta and blood brain barrier; enters breastmilk (small amounts). The plasma protein binding is approximately 50%.

• Metabolism and Excretion

Hyoscyamine metabolized in the liver, partly hydrolyzed to tropic acid, tropine and hyoscyamine glucuronide. It is excreted mainly via urine (as unchanged drug within the 1st 12 hours).

• https://www.practo.com/medicine-info/hyoscyamine-1426-api
• https://www.rxlist.com/levsin-drug.htm#precautions
• https://www.uptodate.com/contents/hyoscyamine-drug-information#F181178
• https://www.drugs.com/mtm/hyoscyamine.html