Hyoscyamine Sulfate - Indications, Contraindications, Side Effects, Clinical Pharmacology, and Drug Interactions

Overview

Hyoscyamine sulfate is an anticholinergic agent used to treat gastrointestinal problems. It is one of the principal antispasmodic or anticholinergic components of belladonna alkaloids. The drug has antimuscarinic properties and thus can be used for various treatments. The drug is mainly marketed in the United States of America and various other countries but is not approved by the FDA (Foods and Drug Administration) for use. However, the drug is readily absorbed by the gastrointestinal tract and gets excreted in the urine in an unchanged form with 12 hours of intake.

What Are the Uses of Hyoscyamine Sulfate?

• Intestinal and stomach problems, including irritable bowel syndrome and cramps.

• Hyoscyamine sulfate is also used to treat cramps caused by gallstones and kidney stones, Parkinson’s disease, and various bowel and bladder control problems.

• The drug is also used to reduce the side effects of insecticides and certain medications used for myasthenia gravis.

• Hyoscyamine is also used to decrease the amount of saliva and sweat released from the body.

• The drug also decreases acid released in the stomach by relaxing organ muscles such as the stomach, bladder, intestine, gallbladder, and kidney, and also slows down the movement of the gut.

Dose and Administration

One or two tablets of Hyoscyamine sulfate are usually prescribed three to four times a day to be taken approximately one hour before a meal or at bedtime. The dosage is recommended for adults and adolescents of 12 years and above. The dose can be readjusted every four hours according to the patient’s need. However, the dose of Hyoscyamine sulfate should not be given more than 12 tablets in 24 hours.

Warning and Precautions

• Diarrhea: It occurs as a result of incomplete intestinal obstruction, usually in patients having colostomy or ileostomy. Therefore, the drug should be discontinued in such cases.

• Psychosis: Patients who are hypersensitive to anticholinergic drugs develop psychosis after using the drug, and these symptoms usually get resolved within 12 to 24 hours after discontinuing Hyoscyamine sulfate.

• Central Nervous System Effects: The drug causes impairment of physical and mental health, leading to blurred vision and drowsiness. Therefore, a person is warned to use heavy machinery and drive as it requires mental alertness.

• Heat Prostration: Increased environmental temperature causes heat prostration in patients. Therefore, the drug should be cautiously used in hot weather conditions and while exercising.

• Hyperthyroidism: The drug should be cautiously prescribed to hyperthyroidism patients.

• Cardiovascular Disease: Hyoscyamine sulfate should be carefully given to patients suffering from heart failure, coronary artery disease, hypertension, and tachyarrhythmias. Therefore, tachycardia should be cautiously evaluated before taking this medication.

• Neuropathy: The drug is to be cautiously given to patients with autonomic neuropathy.

• Hiatal Hernia: Hyoscyamine sulfate should be cautiously prescribed to patients suffering from hiatal hernia along with reflux esophagitis.

• Prostatic Hyperplasia: Necessary precautions should be taken while prescribing the drug to prostatic hyperplasia patients.

Use In Specific Populations

• Pregnancy: There is no specific data on humans, but animal studies have shown the adverse effects of Hyoscyamine sulfate on fetuses. Therefore the doctor should analyze the potential benefits and risks and prescribe the drug only when needed.

• Nursing Mothers: The drug should be cautiously given to breastfeeding mothers as Hyoscyamine sulfate gets excreted in human milk.

• Pediatric Use: The safety and effectiveness of Hyoscyamine sulfate in children below the age of two years is not yet established.

• Geriatric Use: Hyoscyamine sulfate should be carefully prescribed to geriatric patients, with doses usually starting from low concentration. The drug can cause decreased renal, hepatic, and cardiac function, and the risk of developing toxic reactions may be higher in patients with impaired renal function.

For Patients

What Is Irritable Bowel Syndrome?

Irritable bowel syndrome is a gastrointestinal tract disorder affecting the stomach and intestines. The condition causes bloating, cramping, abdominal pain, constipation, and diarrhea and therefore requires long-term medical management.

Why Is Hyoscyamine Prescribed by the Doctor?

Hyoscyamine sulfate is used to control or treat gastrointestinal tract-related symptoms. The drug helps to decrease the movement of the stomach and intestines and also the secretion of stomach fluids and acids.

What Special Precautions Should Be Taken While Using Hyoscyamine Sulfate?

• A person should inform the doctor if they are allergic to Hyoscyamine sulfate or any other medication and ingredients of a Hyoscyamine capsule, tablet, or liquid.

• Also, a person should inform the doctor about all the prescription and non-prescription medications, nutritional supplements, herbal products, and vitamins that a person is taking. This helps the doctor to monitor the side effects and also change the medication dose according to the need of the patient’s condition.

• A person should also inform the doctor about their past and present medical condition including, glaucoma, liver, heart, lung, and kidney disease, intestinal obstruction, and urinary tract.

• A person should cautiously take antacids along with Hyoscyamine as it can make the drug less effective. Therefore, it should be taken at least one hour prior or two hours after taking antacid.

• Women planning to conceive or breastfeed or are pregnant while taking Hyoscyamine sulfate should inform the doctor immediately.

• People older than 65 years should not take this medication and ask the doctor about the risks and benefits of this medication as it is not more effective than other medicines that can treat similar conditions.

• The drug can make a person drowsy; therefore, people should not drive or operate heavy machinery while taking this medication.

• Avoid taking alcohol along with this medication, as it can worsen the side effects of Hyoscyamine sulfate.

What Are the Side Effects of Hyoscyamine Sulfate?

Common Side Effects of Hyoscyamine Sulfate:

• Dizziness.

• Drowsiness.

• Dry mouth.

• Headache.

• Constipation.

• Flushing.

• Blurred vision.

• Increased sensitivity to light.

• Difficulty in urinating.

Serious Side Effects of Hyoscyamine Sulfate:

• Eye pain.

• Skin rash.

• Diarrhea.

• An irregular or fast heartbeat.

Drug Overdose and Missed Dose: Contact the poison control department in case of a drug overdose, and if the person collapses, has trouble breathing, and has seizures, contact the emergency service at 911.

• Acute Overdose: The symptoms of acute drug overdose from Hyoscyamine sulfate include nausea, vomiting, dizziness, headaches, dilated pupils, dry mouth, urinary retention, fever, hypertension, hypotension, etc. Acute overdose can be managed with gastric lavage or emesis, or activated charcoal therapy along with supportive treatment. In addition, an injection of Physostigmine can be given intravenously to reverse the anticholinergic symptoms.

In case of a missed dose, a person should immediately take the dose as soon as they remember. If it is time for the next dose already, take the scheduled dose and skip the missed dose to avoid a double dose or make up for the missed dose.

• Drug Storage and Disposal: Hyoscyamine sulfate should be stored in its airtight container at room temperature, away from moisture and heat, and also away from children. The drug should not be flushed in toilets once not in use or after expiry. They should be properly discarded as per FDA guidelines for the safe disposal of drugs.

For Doctors

Clinical Pharmacology

Mechanism of Action

Hyoscyamine sulfate belongs to a class of antispasmodics and anticholinergics drugs. The drug is non-selectively and competitively antagonizes muscarinic receptors in the cardiac muscles, smooth muscles, atrioventricular node, sino-atrial node, respiratory tract, gastrointestinal tract, and exocrine nodes. The antagonism of muscarinic receptors (M1, M4, and M5) causes cognitive impairment, antagonism of M2 in the atrioventricular and sino-atrial nodes causes an increase in atrial contractility and heart rate, M3 antagonism in the smooth muscles causes bladder contraction, gastric secretion, reduced peristalsis, salivary secretion, sweating, mydriasis, increased bronchodilation, and cycloplegia.

Pharmacodynamics

Hyoscyamine sulfate is not approved by FDA (Foods and Drugs Administration) and therefore has no official indications specified. However, the drug is commonly used as an antimuscarinic agent in various therapies and treatments. The drug is usually prescribed multiple times a day due to its short duration of action. Therefore, a doctor should counsel the patient about various side effects, risks, and signs of anticholinergic toxicity.

Pharmacokinetics

Absorption

Hyoscyamine sulfate can be easily absorbed by oral and sublingual routes. However, there is no specific data available regarding T(max), C(max), and AUC.

Distribution

The drug gets completely distributed in the body, and the small amount can also cross the blood-brain barrier and placenta and thus enters breast milk. The drug has approximately 50 percent of plasma protein binding.

Elimination

Hyoscyamine sulfate gets eliminated in the urine in the form of an unmetabolized parent compound.

Half-life

The half-life of Hyoscyamine sulfate is 3.5 to four hours.

Ingredients

• Active Ingredients: Hyoscyamine sulfate.

• Inactive Ingredients: Colloidal silicon dioxide, lactose monohydrate, magnesium stearate, peppermint flavor, stearic acid, starch, and microcrystalline cellulose.

Dosage Forms and Strength

• Dosage Form: Hyoscyamine sulfate is available in the form of oral tablets, oral capsules, oral solutions, and injectable solutions.

• Dosage Strength: The drug is available in various strengths - 0.5 mg/L, 0.125 mg, 0.125 mg/5L, 0.375 mg, 0.15 mg, 0.125 mg/mL, 0.375 dual release, sulfate, and hydrobromide.

Methods of Administration of the Drug

Oral Dosage:

• 0.125 to 0.25 mg (maximum 1.5 mg per day) of Hyoscyamine sulfate to be given every four to eight hours - For immediate release.

• 0.375 to 0.75 mg of the drug every 12 hours or 0.375 mg every eight hours - extended-release.

• Intramuscular (IM), intravenous (IV), and subcutaneous: 0.25 to 0.5 mg is given four times daily after every four hours.

Contraindications

Hyoscyamine sulfate is contraindicated in the following conditions:

• Obstructive uropathy.

• Glaucoma.

• Paralytic ileus.

• Obstructive gastrointestinal tract disease.

• Unstable cardiovascular status.

• Severe ulcerative colitis.

• Myasthenia gravis.

• Toxic megacolon.

• Myocardial ischemia.

Adverse Effects

Common adverse effects of Hyoscyamine include:

• Dizziness.

• Drowsiness.

• Tachycardia.

• Flushing.

• Palpitations.

• Confusion.

• Fatigue.

• Psychosis.

• Nervousness.

• Headache.

• Hallucinations.

• Insomnia.

• Constipation.

• Bloating.

• Impotence.

• Xerostomia.

• Urinary retention.

• Decreased lactation.

• Nausea.

• Vomiting.

• Heartburn.

• Blurred vision.

• Hypersensitivity reaction.

• Fever.

• Weakness.

• Speech disturbance.

• Dysphagia.

• Increased intraocular pressure.

• Cycloplegia.

• Ataxia.

• Amnesia.

Drug Interactions

Drug interactions usually occur when Hyoscyamine sulfate is concomitantly administered with drugs such as Haloperidol, antimuscarinics, Phenothiazines, Amantadine, tricyclic antidepressants, antihistamines, monoamine oxidase inhibitors. In addition, antacids may also interfere with the absorption of drugs. Therefore, Hyoscyamine sulfate should be administered before meals, and antacids should be taken after meals.