The Advantages of the Ussing Chamber in Drug Absorption Studies

Abstract

By adding high concentrations of test drugs to an Ussing chamber with rat jejunum, we established a system that yields very high correlations between the rat absorption percentage and the membrane permeability, and that can accurately predict the absorption percentage for rats. An advantage of this technique is that, unlike the results obtained using Caco-2, the slope of the absorption/membrane-permeability curve is gentle, which facilitates a more exact prediction of the absorption percentage. In addition, the results obtained with this technique demonstrated that it could be used to evaluate the absorption percentage of drugs with an affinity for P-glycoprotein (P-gp), which cannot be assessed using Caco-2. This method also allows for cassette screening, which would facilitate evaluation of the contribution of P-gp to absorption in the small intestine. Cassette screening showed that absorption of fexofenadine was unaffected by combination with the P-gp substrate ketoconazole. Consistent with this finding, in vivo studies showed that ketoconazole did not affect the Fa Fg for fexofenadine, a pharmacokinetic parameter that reflects absorption and bioavailability in the small intestine. This confirms the usefulness of the Ussing chamber for cassette screening and also suggests that intestinal P-gp has a minimal contribution to drug absorption.

In Vitro Methods to Study Intestinal Drug Metabolism

“…The equipment is commercially available but custom made equipment is also used. The amount of tissue necessary for one set-up ranges from 3.8 mm 2 [125] -5 mm 2 [126] in the smaller version, to 0.65-1.78 cm 2 in the larger version [104,123,[127][128][129]. The smallest chambers (mm 2 -range) have, up to now, only been used for absorption studies [125,126] and are very promising in the light of the scarce availability of human tissue.…”

“…The chambers have been successfully used up to 90 min [130], 120 min [123,129], 180 min [19,84,104] and even to 8 h as reported by Lampen et al [131] who showed that the conductivity remains constant up to 8 h [131]. Polentarutti et al have validated their Ussing chamber preparations thoroughly and based on the potential difference (PD) (> 4mV small intestine; > 6mV colon), short circuit current (SCC), resistance, permeability for propranolol and mannitol as well as morphological evaluation they have concluded that tissue integrity is maintained up to 180 min [104].…”

“…Ussing chamber preparations are generally incubated under carbogen [123,131,132] with KRB buffer solutions at pH 7.4 [68,104,131] as incubation medium [19,68,104,123,129,131,132], Ussing chamber preparations have also been used at pH 5.5 (luminal side) and pH 7.4 (serosal side) [133] or pH 6.0 both sides [129]. The bidirectional supply of glutamine to the incubation medium has been shown beneficial for the viability of Ussing chamber preparations, as it helps to maintain rat enterocyte ATP content in this system [128].…”

A Novel Nanocapsule Delivery System to Overcome Intestinal Degradation and Drug Transport Limited Absorption of P-glycoprotein Substrate Drugs

“…The tacrolimus across the rat intestinal membrane was studied with the Ussing diffusion chamber (24). Sprague Dawley rats, weighing 280-350 g, were fasted overnight and then anesthetized with sodium pentobarbital (30 mg/kg).…”

<i>In Vitro</i> Study on the Transport of Zinc across Intestinal Epithelial Cells Using Caco-2 Monolayers and Isolated Rat Intestinal Membranes

“…31,32) Compared to other in vivo and in situ methods, this technique is relatively simple and enables quantifying the intestinal membrane , respectively. These three parameters are comparable to those of Caco-2, suggesting that Caco-2 is suitable for an in vitro system to examine the permeation of zinc.…”