Hyoscine hydrobromide

Generic Name

Hyoscine hydrobromide

Also Known As

Scopolamine hydrobromide

L-hyoscine hydrobromide

Brand Names

Kwells

Buscopan Hydrobromide

Scopoderm

Hyoscine Tabs

Travel Calm

Avalon Travel Sickness

Joy-Rides

Formulated as oral tablets, sublingual tablets, transdermal patches, injectable ampoules

Drug Class

Antimuscarinic agent

Belladonna alkaloid derivative

Parasympatholytic (cholinergic antagonist)

Mechanism of Action

Hyoscine hydrobromide competitively blocks muscarinic acetylcholine receptors, particularly M1 and M3 subtypes

It reduces the activity of the parasympathetic nervous system, leading to inhibition of smooth muscle contraction, glandular secretions, and vestibular input

In the central nervous system, it acts on the medullary vomiting center and vestibular nuclei to prevent motion-induced nausea and vomiting

It also reduces gastrointestinal spasms and secretions

Indications

Prevention and treatment of motion sickness (sea, air, or land)

Nausea and vomiting due to inner ear disturbances

Adjunct in anesthesia to reduce secretions and prevent bradycardia

Treatment of gastrointestinal, biliary, or genitourinary spasms

Palliative care for drooling (sialorrhea) and respiratory secretions

Control of extrapyramidal symptoms like drug-induced Parkinsonism (rare use)

Dosage and Administration

Adults – Oral Tablets

Typical dose: 300–600 micrograms 30 minutes before travel

May be repeated every 6–8 hours

Maximum: 1.2 mg/day

Used as a short-term treatment (≤48 hours) for motion sickness

Sublingual Tablets (e.g., Kwells)

Same dosing as above

Dissolve under the tongue for rapid effect

Transdermal Patch (Scopoderm)

Delivers 1.5 mg over 72 hours

Applied behind the ear at least 5–6 hours before travel

Replaced every 3 days as needed

Injectable Form

Used in palliative or perioperative care

Dose: 0.2–0.6 mg IM/IV/SC every 6–8 hours as required

Pediatric Use

Children ≥4 years (oral/sublingual): 150–300 micrograms before travel

Children <4 years: not recommended

Transdermal patches not approved for children

Geriatric Use

Start with lowest effective dose

Caution due to increased risk of confusion, hallucinations, anticholinergic burden

Pharmacokinetics

Onset:

– Oral: 30–60 minutes

– Sublingual: 20–30 minutes

– Patch: ~6 hours

Duration:

– Oral: ~6–8 hours

– Patch: up to 72 hours

Metabolized hepatically

Excreted renally

Crosses blood-brain barrier and placenta

Contraindications

Hypersensitivity to hyoscine or belladonna alkaloids

Angle-closure glaucoma

Prostatic hypertrophy with urinary retention

Pyloric stenosis

Myasthenia gravis

Tachyarrhythmia

Severe ulcerative colitis or intestinal obstruction

Children under 4 years (for oral/sublingual)

Warnings and Precautions

Use caution in elderly due to CNS effects and anticholinergic burden

May cause drowsiness, blurred vision, and impaired coordination – avoid driving or operating machinery

Worsening of narrow-angle glaucoma – monitor intraocular pressure

Exacerbation of urinary retention in patients with prostatic hypertrophy

Risk of heat stroke due to decreased sweating in hot environments

Cognitive impairment and confusion especially in older adults or those with underlying dementia

Abrupt withdrawal of transdermal patch can result in rebound symptoms

Transdermal formulation must be applied with clean hands and disposed of safely

Adverse Effects

Very Common

Drowsiness

Dry mouth

Blurred vision

Common

Dizziness

Nausea

Constipation

Mydriasis

Increased intraocular pressure

Urinary retention

Sedation

Uncommon

Disorientation

Confusion

Hallucinations

Agitation

Tachycardia

Skin reactions at patch site

Rare

Delirium (particularly in elderly or high doses)

Allergic reactions

Paralytic ileus

Pregnancy and Lactation

Pregnancy Category

Generally considered low risk when used intermittently for motion sickness

Avoid use near term due to potential neonatal CNS depression

Transdermal patch may be used under medical guidance

Lactation

Excreted in breast milk in small amounts

Potential for infant sedation and feeding difficulty

Caution advised during breastfeeding

Drug Interactions

Anticholinergic Burden

Additive effects with other anticholinergics (e.g., atropine, oxybutynin, tricyclic antidepressants)

Increased risk of dry mouth, urinary retention, cognitive effects

CNS Depressants

Additive sedation with alcohol, benzodiazepines, opioids, antihistamines

Avoid alcohol while using hyoscine

Glaucoma Medications

May antagonize cholinergic glaucoma therapies

Levodopa

May reduce absorption and therapeutic effect

Potassium Chloride

Risk of GI ulceration if delayed-release potassium tablets are used concomitantly due to delayed gastric emptying

Monoamine Oxidase Inhibitors (MAOIs)

Caution due to potential for additive anticholinergic and CNS effects

Monitoring Parameters

Evaluate for relief of nausea or spasm

Monitor for signs of CNS toxicity (confusion, hallucinations, restlessness) especially in elderly

Assess urinary output in patients with prostatic hypertrophy

Monitor intraocular pressure in glaucoma patients

Observe for local skin reactions in patch users

Counseling Points

Take 30 minutes before travel for best effect

Avoid driving, alcohol, or operating heavy machinery due to drowsiness

Do not cut or split transdermal patches

Dispose of used patches safely away from children and pets

Store away from heat and light

Use sugar-free gum or lozenges to relieve dry mouth

Report visual disturbances or confusion immediately

Comparative Notes

Hyoscine Hydrobromide vs Hyoscine Butylbromide

Hydrobromide crosses blood-brain barrier – used for CNS effects (nausea, motion sickness)

Butylbromide (e.g., Buscopan) is quaternary compound – does not cross BBB – used for GI spasms

Hyoscine vs Cinnarizine for Motion Sickness

Hyoscine is anticholinergic

Cinnarizine is antihistamine with calcium channel blocking effect

Both effective, but cinnarizine may be less sedating

Hyoscine vs Meclizine or Cyclizine

Meclizine and cyclizine are less anticholinergic

Better tolerated in elderly

Hyoscine more potent but more CNS adverse effects

Legal and Regulatory Status

OTC in many countries for motion sickness

Prescription-only for injection or in high-dose transdermal forms

Available under pharmacist supervision for pediatric use