Digoxin Antimuscarinics

Digoxin (cardiac glycoside) and trihexyphenidyl (antimuscarinic drug) must be used with caution in elderly patients. Low doses are recommended in elderly patients to avoid toxicity. Lactulose may be safely administered to elderly patients with constipation. 

DIGOXIN ANTIMUSCARINICS PROPANTHELINE t digoxin levels (30-40%) but only with slow-release formulations Slowed gut transit time allows more digoxin to be absorbed Use alternative formulation of digoxin... 

Antiemetics that act on the vomiting centre have antimuscarinic (their principal mode) and anti-histaminic action (hyoscine, promethazine) they alleviate vomiting from any cause. In contrast, drugs that act on the CTZ (haloperidol, ondansetron) are effective only for vomiting mediated by stimulation of the chemoreceptors (by morphine, digoxin, cytotoxics, uraemia). The most efficacious drugs act at more than one site (Table 31.1). 

Smulders RA, Kuipers ME, Krauwinkel WJJ. Multiple doses of the antimuscarinic agent solifenacin do not affect the pharmacodynamics or pharmacokinetics of warfarin or the steady-state pharmacokinetics of digoxin in healthy subjects. BrJ Clin Pharmacol (2006) 62,210-17. 

Propantheline is an antimuscarinic, which reduces gut motility. This allows the slow-dissolving formulations of digoxin more time to pass into solution so that more is available for absorption. 

Sand e B, Sabounjian L, Shipley J, Profy A, Lasseter K, Fox L, Harnett M Predictive power of an in vitro system to assess dn interactions of an antimuscarinic medication a cemparison of in vitro and in vivo drug-dn interaction studies of trospium chloride with digoxin J Clin Pharmacol (2006) 46,776-84. 

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