“Acetylcholine is a neurotransmitter that can innervate both muscarinic and nicotinic receptors. Drugs typically referred to as anticholinergic can block any one of the five muscarinic (G protein) receptors (M1–M5) found in smooth muscle, motor neurons, the heart, and the central nervous system (CNS). Despite this knowledge, there is no ‘gold standard’ by which medications can be classified as anticholinergic. Some rely on serum anticholinergic activity (SAA) as measured by radioreceptor assay, in-vitro muscarinic receptor affinity (pKi), clinical consensus, or a combination of these three approaches.” Ther Adv Drug Saf. 2016 Oct; 7(5): 217–224.
Classes of drugs with Anticholinergic Activity (JAMA iMed 2015)
Antihistamines
Antivertigo/antiemetics
Antidepressants
Antipsychotics
Gastrointestinal antispasmodics
Bladder antimuscarinics
Skeletal muscle relaxants
Antiarrhythmic
Antiparkinson agents
Meds that could cause acute anticholinergic poisoning
Antihistamines: H1 receptor antagonists (1st generation, eg, brompheniramine, carbinoxamine, chlorpheniramine, clemastine, cyproheptadine, dimenhydrinate, diphenhydramine, doxepin, doxylamine, hydroxyzine, meclizine, triprolidine, others)
Gastrointestinal: Antiemetics (eg, hydroxyzine, meclizine, promethazine, scopolamine); 1st generation antihistamines
Psychotropic:
High relative anticholinergic potency:
-Antipsychotics 1st generation: Chlorpromazine, fluphenazine, loxapine, methotrimeprazine (levomepromazine), thioridazine, trifluoperazine
-Antipsychotics 2nd generation: Clozapine
-Tricyclic antidepressants (eg, amitriptyline, clomipramine, desipramine, doxepin, imipramine, nortriptyline)
Low relative anticholinergic potency:
-Antipsychotics 1st generation: Haloperidol, perphenazine*, others
-Antipsychotics 2nd generation (eg, olanzapine*, quetiapine*, iloperidone, risperidone, others)
Antiparkinson agents: Benztropine, trihexyphenidyl
Antimuscarinic, overactive bladder: Darifenacin, fesoterodine, flavoxate, oxybutynin, solifenacin, tolterodine, trospium
Antimuscarinic, spasmolytic: Atropine, belladonna-containing medications, clidinium-chlordiazepoxide, dicyclomine, hyoscyamine, glycopyrrolate, homatropine, methscopolamine, propantheline, scopolamine (hyoscine)
Muscle relaxant: Cyclobenzaprine, orphenadrine, tizanidine
Antimuscarinic, inhaled bronchodilator: Ipratropium, tiotropium
Antimuscarinic, ophthalmic drops (mydriatic/cycloplegic): Atropine, cyclopentolate, homatropine, scopolamine
Related Article: Antiemetic drugs.
Drugs with high or moderate Anticholinergic (AC) Activity
- Amitriptyline
- Nortriptyline
- Atropine
- Benztropine
- Chlorpheniramine
- Diphenhydramine
- Hydroxyzine
- Meclizine
- Chlorpromazine
- Clomipramine
- Clozapine [high AC activity]
- Cyclobenzaprine
- Cyproheptadine
- Desipramine
- Dexchlorpheniramine
- Dicyclomine
- Doxepin
- Fesoterodine
- Hyoscyamine
- Imipramine
- Mepenzolate
- Olanzapine
- Orphenadrine
- Oxybutynin
- Paroxetine
- Perphenazine
- Prochlorperazine
- Promethazine
- Protriptyline
- Pseudoephedrine HCl/Triprolidine HCl
- Scopolamine
- Thioridazine
- Tolterodine
- Trifluoperazine
- Trimipramine
Other drugs with AC activity
- Alprazolam
- Amantadine
- Baclofen
- Brompheniramine
- Carbamazepine
- Carbinoxamine
- Carisoprodol
- Cetirizine
- Cimetidine
- Clemastine
- Clidinium & chlordiazepoxide
- Clorazepate
- Codeine
- Colchicine
- Darifenacin
- Digoxin
- Dimenhydrinate
- Diphenoxylate plus atropine
- Disopyramide
- Flavoxate
- Fluphenazine
- Furosemide
- Hydrochlorothiazide
- Loperamide
- Loratadine
- Loxapine
- Maprotiline
- Meperidine
- Methocarbamol
- Methotrimeprazine
- Nifedipine
- Olanzapine
- Orphenadrine
- Quetiapine
- Procyclidine
- Propantheline
- Ranitidine
- Solifenacin
- Thiothixene
- Tizanidine
- Tramadol
- Trihexyphenidyl
- Trospium
Further Reading
Ther Adv Drug Saf. 2016 Oct; 7(5): 217–224. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5014048/
JAMA internal medicine. 2015;175(3):401-407. Cumulative Use of Strong Anticholinergic Medications and Incident Dementia. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4358759/
uptodate.com/contents/anticholinergic-poisoning