Inhaled antimuscarinics
Blocking airway muscarinic receptors so vagal acetylcholine cannot narrow them.
Also called inhaled anticholinergics.
Class card
- Drugs
- Ipratropium and Tiotropium
- Used for
- Maintenance treatment of COPD
- Fewer COPD flare-ups (tiotropium)
- Add-on maintenance treatment of asthma (tiotropium)
- Runny nose in perennial rhinitis (ipratropium spray)
- Known for
- Dry mouth
- Name stems
- -trop-
- Part of
- antimuscarinics
3 cards: the class, and each drug in it.
Mechanism of action
How do inhaled antimuscarinics work?
Inhaled antimuscarinics are quaternary relatives of atropine that compete with acetylcholine at muscarinic receptors, mainly M3, on airway smooth muscle and mucus glands. Acetylcholine released by the vagus nerve can then no longer tighten the airways or drive mucus secretion, so the airways widen. Their effect is mainly local in the lungs; ipratropium is short-acting and tiotropium lasts a full day.
The drugs
Inhaled antimuscarinics with a card
Uses
What are inhaled antimuscarinics used for?
- Maintenance treatment of COPD
- Fewer COPD flare-ups (tiotropium)
- Add-on maintenance treatment of asthma (tiotropium)
- Runny nose in perennial rhinitis (ipratropium spray)
Side effects
Side effects of inhaled antimuscarinics
- Dry mouthKnown for
- Constipation
- Difficulty passing urine (urinary retention)Serious
- Narrow-angle glaucoma, blurred vision, eye painSerious
- Palpitations and fast heartbeat
- Headache
- Paradoxical bronchospasmSerious
- Allergic reactions, including angioedemaSerious
What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.
Watch for
Cautions
- They are maintenance bronchodilators, not rescue treatment for acute bronchospasm.
- Narrow-angle glaucoma: they can raise eye pressure, especially if the spray or powder reaches the eyes.
- Prostate enlargement or bladder-neck obstruction raises the risk of urinary retention.
- Other anticholinergic drugs add to their side effects and are best avoided with them.
Remember them
A way to remember them
Block the vagus, open the airways.
The vagus nerve narrows the airways through acetylcholine at muscarinic receptors; these drugs block that signal, and like atropine they can dry the mouth and, rarely, raise eye pressure or hold back urine.
Written for biofideX
Name stems
-trop- means atropine-like antimuscarinic
Marks atropine relatives. Ipratropium and tiotropium add -ium: as quaternary ammonium compounds they are barely absorbed and act in the airways. Somatropin, a growth hormone, fits by chance.
- Every drug name stem
Don't mix them up
Classes easily confused with these
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Ipratropium bromide HFA inhalation aerosol: label (DailyMed)
- Tiotropium bromide inhalation powder: label (DailyMed)
- Ipratropium bromide nasal solution: label (DailyMed)
- Tiotropium bromide (NCI Thesaurus)
- Tiotropium inhalers (NHS)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Lungs and allergy
Practice inhaled antimuscarinics with the other classes in this group: what each drug is, how it works, what it treats and what it's known for.
Start Practicing