PHARMACOLOGY
Antimuscarinics/anticholinergics such as hyoscine hydrobromide, atropine, glycopyrronium/glycopyrrolate and hyoscine butylbromide are used primarily as smooth muscle antispasmodics and antisecretory agents. They are used in palliative care for intestinal colic, genitourinary colic, inoperable bowel obstruction with colic, and respiratory secretions at the end of life. Hyoscine hydrobromide and glycopyrronium/glycopyrrolate are less likely to cross the blood-brain barrier and cause central side-effects (e.g. delirium) because less lipid-soluble.
Effective in reducing respiratory secretions at end of life in about ½ to ⅓ of patients
Onset of action: 10 minutes SC/IM/IV
Time to peak plasma concentration: 1-2 h PO
Plasma ½ life: 5-6 h
DOSING
- 20 mg as a single dose SC. If effective, continue, using 20 mg q4h SC
- Less than 6 years: 0.3 mg/kg/dose tid PO/SC/IV
- 6-12 years: 5-10 mg up to tid PO/SC/IV
UNWANTED EFFECTS
- Blurred vision
- Cardiovascular effects
- Dry mouth
- Constipation
- Heartburn
- Urinary retention
- Delirium
PITFALLS/CONCERNS
- Avoid concurrent use with prokinetics as antimuscarinics will block the action of agents such as metoclopramide
- Glaucoma may be precipitated in patients at risK
NOTE
This information is drawn from a number of sources (see below). The reader is encouraged to access these and other relevant literature for more detail. As always, sound clinical judgment should be used in individual clinical cases. In particular, it should be remembered that there may be significant variation in the pharmokinetics of a drug resulting from a number of factors, including the individual patient’s metabolism/disease status and how the medication has been formulated.
SOURCES/REFERENCES
- Brunton LL, Lazo JS, Parker KL, editors. Goodman and Gilman’s: the pharmacological basis of therapeutics. 11th ed. McGraw-Hill Professional; 2006.
- Twycross R, Wilcock A. Palliative care formulary. 3rd ed. Radcliffe Medical Press Ltd; 2008.
- Repchinsky C, editor. Compendium of pharmaceuticals and specialties (CPS): the Canadian drug reference for health professionals. 44th ed. Canadian Pharmacists Association; 2009.
- Goldman A, Hain R, Liben S. Oxford textbook of palliative care for children. 1st ed. Oxford University Press; 2006.
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