HYOSCINE BUTYLBROMIDE INJECTION BP

Indications

• Nausea and vomiting due to motion sickness
• Palliative care for excessive respiratory secretions
• Premedication prior to surgery
• Management of bowel colic

Dosage

Children: Refer to the BNF for Children for specific dosing information; dosage

Adults: For motion sickness, the recommended dosage is 150–300 micrograms taken 30 minutes before travel, followed by 150–300 micrograms every 6 hours as needed, with a maximum of 900 micrograms per day. For palliative care and other indications, doses may vary; refer to BNF for specific guidance.

Mechanism of action

Hyoscine hydrobromide exerts its effects by antagonizing muscarinic receptors, particularly M1 receptors located in the vestibular system and the vomiting center of the brain. This action reduces the excitatory input from the vestibular system, which is responsible for motion sickness. Additionally, it diminishes gastrointestinal motility and secretions, effectively alleviating symptoms of nausea and vomiting.

Pharmacodynamics

As an anticholinergic agent, hyoscine hydrobromide decreases the activity of the parasympathetic nervous system. Its sedative effects can also lead to drowsiness and sedation, which may be beneficial in some patients but could impair the ability to perform skilled tasks. Its antimuscarinic properties can result in side effects like dry mouth, urinary retention, and blurred vision due to reduced secretions and muscle relaxation.

Pharmacokinetics

Hyoscine hydrobromide is well absorbed after oral administration, with peak plasma concentrations typically reached within 1 hour. It has a half-life of approximately 3 to 6 hours. The drug is extensively metabolized in the liver, and its metabolites are excreted primarily through the kidneys. Its effects can vary based on the route of administration, with transdermal patches providing prolonged action.

Contra-indications

• Asthma
• Bronchiectasis
• Bronchitis
• Epilepsy
• Severe coronary artery disease
• Pyloroduodenal obstruction
• Susceptibility to angle-closure glaucoma
• Urinary retention

Adverse effects

• Anticholinergic syndrome
• Anxiety
• Decreased appetite
• Arrhythmia
• Blood disorders
• Increased bronchial secretion viscosity
• Confusion
• Dizziness
• Drowsiness
• Dry mouth
• Epigastric discomfort
• Fatigue
• Haemolytic anaemia
• Headache
• Hypotension
• Jaundice
• Movement disorders
• Muscle spasms
• Nightmares
• Palpitations
• Photosensitivity reaction
• Urinary retention
• Blurred vision

Interactions

• Antihistamines
• Sedatives
• Clozapine therapy

Precautions

• Caution in elderly patients due to increased susceptibility to anticholinergic side effects
• Use with caution in hepatic impairment
• Use with caution in renal impairment
• May impair performance of skilled tasks (e.g. driving or cycling) due to drowsiness

Pregnancy

Most manufacturers advise avoiding use during pregnancy; however, there is no evidence of teratogenicity. Use in the latter part of the third trimester may cause adverse effects in neonates such as irritability, paradoxical excitability, and tremor.

Breast-feeding

Most antihistamines are present in breast milk in varying amounts; although not known to be harmful, most manufacturers advise avoiding their use in breastfeeding mothers.

Storage

Store at room temperature, away from moisture and heat.

Formulations

• Tablets
• Sublingual tablets
• Transdermal patches
• Subcutaneous injection
• Intramuscular injection
• Continuous subcutaneous infusion

Mechanism of action

Butyl compounds act by interacting with various biological pathways depending on their specific structure. For example, in the context of pharmaceutical use, they may function as solvents for drugs, enhancing solubility and bioavailability, or may have specific receptor interactions based on their functional groups. The precise mechanism of action would vary with the specific butyl derivative.

Pharmacodynamics

The pharmacodynamics of butyl compounds can vary widely. Generally, they may affect various physiological processes depending on their chemical nature. For example, butyl derivatives may exhibit anti-inflammatory, analgesic, or even anesthetic properties in certain contexts. The pharmacodynamic profile is largely dependent on the specific butyl compound and its interactions with cellular receptors and enzymes.

Pharmacokinetics

The pharmacokinetics of butyl compounds vary significantly among different derivatives. Commonly, these compounds are absorbed through various routes, depending on their formulation. They may undergo metabolic processes in the liver before being excreted primarily via urine. The exact absorption rates, half-lives, and clearance rates would depend on the specific butyl derivative and its formulation.

Pregnancy

There are no specific studies regarding the use of butyl compounds in pregnancy. Caution should be exercised.

Breast-feeding

There is limited information on the excretion of butyl compounds in human breast milk. Caution is advised.

Storage

Store in a well-closed container, protected from light and moisture.

Indications

• Irritable bowel syndrome
• Other gastrointestinal disorders associated with smooth muscle spasms

Dosage

Children: Refer to the BNF for Children for specific dosing information.

Adults: Refer to the BNF for specific dosing information.

Mechanism of action

Butylbromide acts as a competitive antagonist of muscarinic acetylcholine receptors. This inhibition decreases the contractility of smooth muscle in the gastrointestinal tract, leading to reduced spasms and discomfort. It predominantly affects the parasympathetic nervous system, which regulates involuntary bodily functions.

Pharmacodynamics

The pharmacodynamic effects of butylbromide include relaxation of smooth muscle and reduction of secretions in the gastrointestinal tract. This results in decreased gastrointestinal motility and relief from cramping and pain associated with smooth muscle contractions. The onset of action is typically rapid, making it effective for acute symptoms.

Pharmacokinetics

Butylbromide is absorbed from the gastrointestinal tract following oral administration. It is distributed throughout the body, with a preference for tissues with high cholinergic activity. The drug undergoes hepatic metabolism, and its metabolites are excreted primarily through the urine. The half-life and exact pharmacokinetic parameters can vary depending on individual patient factors.

Pregnancy

Butylbromide should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether butylbromide is excreted in human milk. Caution should be exercised when administering to breastfeeding mothers.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Indications

• Motion sickness
• Nausea and vomiting
• Pre-operative sedation
• Spasmodic disorders of the gastrointestinal tract

Dosage

Children: Refer to the BNF for Children for specific dosing guidelines.

Adults: Refer to the BNF for specific dosing guidelines.

Mechanism of action

Hyoscine exerts its effects primarily by antagonizing muscarinic acetylcholine receptors, which inhibits cholinergic transmission in the central nervous system and peripheral tissues. This results in decreased gastrointestinal motility, reduced salivation, and diminished vestibular sensitivity, which are beneficial in preventing nausea and vomiting associated with motion sickness.

Pharmacodynamics

The pharmacodynamic effects of hyoscine include sedation, amnesia, reduction of motion sickness symptoms, and relaxation of smooth muscles in the gastrointestinal tract. These actions are dose-dependent, and the drug may also exhibit peripheral anticholinergic effects such as decreased secretions in the respiratory tract.

Pharmacokinetics

Hyoscine is well absorbed from the gastrointestinal tract and can also be administered transdermally or via injection. It has a bioavailability of approximately 90% when taken orally. The drug undergoes extensive hepatic metabolism, and its elimination half-life is about 3 to 6 hours. It is primarily excreted in the urine as metabolites, and the onset of action varies based on the route of administration.

Contra-indications

• Hypersensitivity to hyoscine or any of its excipients
• Myasthenia gravis
• Severe glaucoma
• Prostatic hypertrophy
• Obstructive gastrointestinal disease

Adverse effects

• Drowsiness
• Confusion
• Dry mouth
• Blurred vision
• Constipation
• Urinary retention
• Tachycardia

Interactions

• clozapine+hyoscine: Unknown (additive effect)
• antipsychotics, second generation+hyoscine: Unknown (additive effect)

Precautions

• Use with caution in patients with cardiovascular disease
• May impair the ability to drive or operate machinery
• Caution in patients with a history of seizures

Pregnancy

Hyoscine should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult relevant guidelines.

Breast-feeding

Hyoscine is excreted in breast milk. Caution should be exercised when administering to breastfeeding mothers.

Storage

Store in a cool, dry place, away from light. Keep out of reach of children.

Formulations

• Tablets
• Injectable solution
• Transdermal patch