Antimuscarinics (inc. ipratropium bromide + tiotropium) Flashcards
What are the indications for ipratropium bromide?
-Reversible airways obstruction (i.e., Asthma)
-Nebulised ipratropium bromide can be combined with a nebulised beta2 agonist for children with a poor initial response to just a beta agonist alone in a severe/life threatening asthma attack
-Acute bronchospasm
-Rhinorrhoea associated allergic with non-allergic rhinitis
- COPD
What is the pharmacodynamic of antimuscarinics?
Short acting antagonist of the muscarinic acetylcholine receptors (part of the parasympathetic system)
REMEMBER: the parasympathetic system causes bronchoconstriction
What is the pharmacokinetic of ipratropium bromide?
Oral/inhaled bioavailability = 1-2% (very low)
Protein binding = 0-9%
Half-life = 1.6 hours
Metabolism = CYP enzymes (liver)
Excretion = 80-100% urine (kidneys)
What are the contraindications and cautions for ipratropium bromide?
DO NOT use if there is Hx of allergy
CAUTIONS
Bladder outflow obstruction
Paradoxical bronchospasm
Prostatic hyperplasia
Susceptibility to angle-closure glaucoma
Cystic fibrosis
What is the typical dose of ipratropium bromide in adults and children aged 12 years and older?
20-40 micrograms daily
TDS/QDS
What is the typical dose of ipratropium bromide in children aged 6-11 years?
20-40 micrograms daily
TDS
What is the typical dose of ipratropium bromide in children aged 1 month to 5 years?
20 micrograms daily
TDS
What is the typical dose of tiotropium in adults?
5 micrograms
OD
N.B. not currently used in children
What are the adverse effects of antimuscarinics (i.e., ipratropium and tiotropium)?
Constipation
Cough
Diarrhoea
Nausea
Dry mouth
GI motility disorder
Headache
Sinusitis
Stomatitis
Narrow angle glaucoma
What should you do if a patient develops eye symptoms (e.g., eye pain or discomfort, blurred vision, visual halos, or coloured images in association with red eyes from conjunctival congestion and corneal oedema) whilst on antimuscarinics?
Give miotic drops
Seek urgent specialist advice
Name other adverse effects of ipratropium specifically
Laryngospasm
Pharyngeal oedema
Vomiting
Ocular accommodation disorder (rare)
Name other adverse effects of tiotropium specifically
Gingivitis
Glossitis
Insomnia
What are the drug interactions for the anticholinergics?
Ipratropium + beta-2 agonists/xanthines = additive bronchodilatory effect
Also avoid using with other drugs that have anti-muscarinic effects unless absolutely necessary
Sources
https://bnf.nice.org.uk/drugs/ipratropium-bromide/
https://go.drugbank.com/drugs/DB00332
https://go.drugbank.com/drugs/DB01409
https://cks.nice.org.uk/topics/asthma/prescribing-information/muscarinic-agents/#dose
