Spectral properties and ionization behavior of retinoids, II.

Kinetic Study of a 2‐Hydroxypropyl‐β‐Cyclodextrin‐Based Formulation of all‐trans‐Retinoic Acid in Sprague‐Dawley Rats After Oral or Intravenous Administration

“…3 It has been suggested that oral absorption of ATRA depends on the pH, the fatty acid composition, and the inherent bile salt solubilization capacity of the intestine. 6,7,28,29 In this study, the delayed absorption of ATRA observed in Group 1 could be explained by the slow solublization of ATRA in the weakly alkaline intestinal fluid. When ATRA was formulated as a HP␤CD complex for oral administration, the rate and extent of its absorption were improved substantially (Figure 2).…”

“…ATRA has almost nil aqueous solubility, 1 the problems of low water solubility and strong tendency to self-associate will pose great difficulties in formulating it into suitable oral and parenteral dosage forms. 28,29 As the oral absorption of most retinoids is increased with food, differing dietary regimens may contribute to the wide intra-and inter-patient variation in peak plasma ATRA concentrations reported in some studies. 3 It has been suggested that oral absorption of ATRA depends on the pH, the fatty acid composition, and the inherent bile salt solubilization capacity of the intestine.…”

Development of Smart Semisolid Formulations to Enhance Retinoic Acid Topical Application

“…Initially, the detection of RET released from the hybrids was performed by UV spectrophotometry; however, this method did not result suitable because of some limitation associated both to the chemical nature and low solubility of the molecule. As clearly reported in literature, when RET is in a water solution, it tends to form aggregates (such as tail‐to‐tail dimers) or micelles that present a different spectrum in comparison to that deriving from free molecules in solution . Thus, an alternative method was adopted to confirm the effective RET deintercalation from hybrids.…”

“…As clearly reported in literature, when RET is in a water solution, it tends to form aggregates (such as tail-to-tail dimers) or micelles that present a different spectrum in comparison to that deriving from free molecules in solution. 23,24 Thus, an alternative method was adopted to confirm the effective RET deintercalation from hybrids. Namely, it was decided to recover the hybrid from the dissolution medium by centrifugation and to collect its X-ray pattern.…”

Superoxidation of Retinoic Acid†

“…The peaks located at 16 Da and 32 Da are consistent with reports of formation of the 5,6-epoxide and the 5,8-endoperoxide, respectively (7,8) . In both the CHzCl2 and ethanol solutions there is little communication between neighboring polyene systems (13,14). Figure 3 shows the APCI-MS of the aqueous ethanolic solution of retinoic acid after irradiation (Eq.…”