Glycopyrronium: Effect as a peripheral anticholinergic

Glycopyrronium (also called glycopyrrolate, brand names Seebri Breezhaler in COPD therapy, Sialanar as an oral solution for hypersalivation, Robinul intravenously in anesthesia) is a quaternary anticholinergic with predominantly peripheral action. Unlike tertiary anticholinergics such as atropine or scopolamine, glycopyrronium poorly crosses the blood-brain barrier. This makes it particularly valuable because central adverse effects such as confusion, hallucinations, or sedation occur much less frequently.

In Germany, glycopyrronium has three clinically relevant applications: as a long-acting anticholinergic for inhalation in chronic obstructive pulmonary disease (COPD), as an oral solution for treating severe hypersalivation in children with neurological disorders, and as a parenteral adjunct in anesthesia to reduce secretory and vagal reflexes. Topical application as a solution for axillary hyperhidrosis is another relevant indication.

Mechanism of action

Glycopyrronium competitively blocks muscarinic acetylcholine receptors of subtypes M1 through M3 in smooth muscle, glands, and the heart. At the bronchial mucosa, M3 blockade leads to bronchodilation and reduces mucus secretion. At exocrine glands (salivary, sweat, bronchial glands), glycopyrronium significantly inhibits secretion. At the heart, it acts via M2 blockade to slightly increase heart rate.

The quaternary ammonium structure and high polarity prevent significant passage through the blood-brain barrier. This explains the clinical advantage over atropine or scopolamine: fewer central adverse effects, less confusion, less sedation. In elderly patients and in pediatrics, this property is particularly valuable.

Pharmacokinetics differ depending on the route of administration. When inhaled, glycopyrronium acts long-term (24 hours of bronchodilation) with minimal systemic absorption. Orally, it has low bioavailability (approximately 3 to 5 percent), which is why multiple daily doses are necessary. Intravenously, the effect occurs within 1 minute, the half-life is around 0.8 to 1.3 hours, and the duration of action is 2 to 3 hours.

Indications

• Chronic obstructive pulmonary disease (COPD), inhaled as a long-acting anticholinergic (LAMA), often in fixed combination with long-acting beta 2 agonists
• Severe hypersalivation in children with neurological disorders (for example, cerebral palsy), oral solution
• Reduction of secretory and vagal reflexes in anesthesia, parenteral administration together with opioids or neuromuscular antagonists
• Antagonism of non-depolarizing neuromuscular blocking agents, in combination with neostigmine as a peripheral anticholinergic to reduce bradycardic and bronchospastic effects
• Axillary hyperhidrosis, topical solution in specialized dermatological application
• Palliative secretion control for death rattle at end of life, parenteral or subcutaneous

Glycopyrronium is not first-line for acute allergic reactions, asthma as an initial medication, or for central nervous system applications. Self-medication is not available.

Dosage and administration

COPD inhalation: 50 µg once daily (Seebri Breezhaler), as a powder inhalation. For fixed combinations with beta 2 agonists or glucocorticoids, dosages are adjusted accordingly.

Hypersalivation in children (Sialanar): Start 12.8 µg per kg body weight three times daily (equivalent to glycopyrronium bromide 16 µg per kg three times daily), increase to clinical effect, maximum 64 µg per kg three times daily glycopyrronium bromide.

Anesthesia intravenous: 0.2 to 0.4 mg as a bolus, in combination with neostigmine 0.01 to 0.02 mg per kg glycopyrronium. For bradycardia, 0.1 to 0.2 mg intravenously.

Palliative secretion control: 0.2 to 0.4 mg subcutaneously every 4 to 6 hours or continuous infusion 0.6 to 2.4 mg per 24 hours.

Renal impairment: with eGFR below 30 ml per minute, caution and reduced dose, because glycopyrronium is eliminated primarily via the kidneys. Hepatic impairment: dose adjustment usually not required.

Inhalation technique: Prepare the powder inhaler correctly, take a deep rapid breath, hold breath for 5 to 10 seconds, then exhale. Rinse mouth after inhalation.

Wash hands after oral administration of Sialanar, because accidental eye contact can lead to pupil dilation and visual disturbances.

Adverse effects

Common: dry mouth, constipation, urinary retention, blurred vision with accommodation disorder, skin redness, increased skin warmth.

Occasional: tachycardia, palpitations, nausea, abdominal pain, allergic skin reactions, local irritation at the site of application (inhalation or topical).

Rare: acute angle-closure glaucoma in predisposed patients, paradoxical bronchospasm, AV block at higher doses, acute confusion (very rare due to poor CNS penetration, but still possible at very high doses or in elderly patients).

Heat intolerance: Anticholinergics reduce sweating, which increases the risk of hyperthermia during heat waves. Pay attention to this especially in elderly people and children, and ensure adequate hydration.

In children on Sialanar: behavioral changes, sleep disturbances, constipation, increased respiratory tract infections, and growth monitoring must be clinically monitored.

Drug interactions

• Other anticholinergics (tricyclic antidepressants, first-generation antihistamines, antispasmodics, other inhaled anticholinergics such as tiotropium): additive anticholinergic effects with confusion, tachycardia, and urinary retention.
• Cholinesterase inhibitors (donepezil, rivastigmine, pyridostigmine): pharmacological antagonism, mutual weakening of effects.
• Beta blockers: no specific interaction, both can be combined in COPD therapy.
• Sympathomimetics (beta 2 agonists such as salbutamol, formoterol, indacaterol): synergistic bronchodilatory effect desired, frequent fixed combination.
• Antiarrhythmics: caution regarding tachycardia risk, especially with class Ia and III substances.
• Gastrointestinal motility-promoting substances (metoclopramide, domperidone, prucaloprid): mutual weakening of effects.

Special notes

Pregnancy: Data limited. If necessary, use based on individual risk-benefit assessment. Breastfeeding: Passage into breast milk not sufficiently investigated, use only after individual consultation.

Children: Sialanar is approved from 3 years of age for severe hypersalivation in neurological indications. From childhood, caution regarding anticholinergic effects, regular follow-up examinations.

Elderly patients: despite poor CNS penetration, caution regarding fall risk, constipation, and urinary retention. Low starting dose, regular clinical assessment.

Before starting therapy: Take history of acute angle-closure glaucoma, severe gastrointestinal disease with atony, myasthenia gravis, prostatic hyperplasia with residual urine. These conditions are contraindications or conditions requiring particular caution.

In asthma: Glycopyrronium is not primarily approved for asthma. In COPD with asthma component, individual assessment.

With Sialanar: take the oral solution 30 minutes before or at least 2 hours after a meal, because food reduces bioavailability.

Ability to drive: blurred vision may impair driving ability, individual assessment. With stable therapy usually maintained.

You might also be interested in

• Scopolamine, anticholinergic agent with CNS effect
• Trospium, peripheral anticholinergic for overactive bladder
• Trospium chloride, salt form of trospium
• Neostigmine, peripheral cholinesterase inhibitor in anesthesia
• Acetylcholine, neurotransmitter and mechanism of action

Frequently asked questions

Sources

• Gelbe Liste, Glycopyrronium active substance profile
• BfArM, Federal Institute for Drugs and Medical Devices
• AWMF, Guidelines on COPD and hypersalivation
• GOLD Initiative, COPD recommendations