Digoxin dosage forms

Doherty, J. E. et al., A multicenter evaluation of the absolute bioavaUability of digoxin dosage forms, Curr. Ther. Res., 35 301-306, 1984. 

Diarrheal conditions may decrease drug absorption as a result of reduced intestinal residence time. The absorption of several drugs was decreased in response to lactose- and saline-induced diarrhea [145]. Digoxin absorption from tablets was impaired in one subject who developed chronic diarrhea as a result of x-ray treatment [146]. Abdominal radiation or the underlying disease has been shown to reduce digoxin and clorazepate absorption [147]. A dosage form that provides rapid drug dissolution (e.g., solution) may partially resolve this problem. 

Dosage adjustment when changing preparations The differenee in bioavailability between digoxin injeotion or oapsules and pediatrie elixir or tablets must be oonsidered when ohanging patients from 1 dosage form to another. 

Because P-gp expression was reported to increase from the proximal to the distal regions of the small intestine (Yumoto et al. 1999), Lacombe et al. suggested gastroretentive or immediate release dosage forms for the delivery of P-gp substrates (Lacombe et al. 2004). It has been shown, for example, in everted gut sacs of rats that the transport of digoxin is about 2.5-fold higher in the proximal jejunum in comparison to the terminal ileum. 

Drugs that meet one or more of the criteria given above and have been shown to exhibit significant differences in the bioavailability of marketed dosage forms include digoxin, quinidine, furosemide, nitrofurantoin, prednisone, chloramphenicol, theophylline, chlorpromazine, phenytoin, amitriptyline, and phenylbutazone. 

Yacobi A (1981). The assessment of intersubject variability in digoxin absorption in man from two oral dosage forms. / Clin Pharmacol 21 301-310. 

It has also been suggested that the interaction between digoxin and talinolol may be dosage form dependent. More study is needed. 

Broadhead J, Ruan SK, Rhodes CT. The effect of process and formulation properties on the properties of spray dried 3-galactosidase. J Pharm Pharmacol 1994 46 458-467. Kim CK, Soon YS. Development of digoxin dry elixir as a novel dosage form using a spray-drying technique. J Microencap 1995 12(5) 547-566. 

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