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To evaluate the bioavailability of exemestane (EXM) from self-micro emulsifying drug delivery systems (SMEDDS) and suspension formulations, a sensitive, specific, and rapid liquid chromatography-mass spectrometric method was developed and validated. The analyte was extracted from plasma samples and detected by mass spectrometry (MS) with an atmospheric pressure positive-ion chemical ionization (APCI) mode using a heated nebulizer interface. Progesterone (PGS) was used as the internal standard. A Hychrome RPB-L428 column was used to perform the chromatographic separation, the mobile phase being methanol and 15 mM ammonium formate (80:20). The MS detection used a heated nebulizer interface, with multiple reaction monitoring (MRM) operated in positive-ion mode. Both, EXM and PGS were well-separated and identified by their relative retention times, that is, 1.13 and 1.84 min, respectively. After oral administration of EXM loaded SMEDDS and suspension formulation to rats, a significant difference was observed in the pharmacokinetic behavior of drug in both the formulations, and a 2.9-fold increase in the relative bioavailability of EXM was observed with the SMEDDS as compared with suspension formulation. The developed method was found to be suitable for bioanalysis of exemestane and, hence, successfully depicted the bioavailability enhancement of exemestane SMEDDS in Wistar rats. [ABSTRACT FROM AUTHOR]

A simple, sensitive, and selective ultra-performance liquid chromatographic (UPLC) method with quadrupole-time of flight-mass spectrometric (Q-TOF-MS/MS) detection was developed for the determination of moxifloxacin (moxi) in rabbit aqueous humor. After a simple protein-precipitation by acetonitrile, the post-treatment samples were separated on a UPLC Bridged Ethyl Hybrid (BEH) C-18 column with 0.1% formic acid in water as a mobile phase and analyzed in positive ion mode. The method developed was validated in rabbit aqueous humor with a daily working range of 0.1–200 ng/mL with correlation coefficient, r2 > 0.999 and a sensitivity of 0.12 ng/mL as limit of quantification. The method proved to be accurate (recovery, 96.0–99.3%), precise (%RSD, ≤0.71%), and specific and was applied to evaluate the moxifloxacin loaded nanoplexes (moxi-NPX) as vehicles for ocular drug delivery. Moxi-NPX (4037 ± 45.9 ng/mL hr) provided approximately five-fold increase in the relative ocular bioavailability compared with moxi solution (806.5 ± 32.5 ng/mL hr). In conclusion, moxi-NPX increases ocular bioavailability of moxi, prolongs its residence time in the eye, and are efficient ocular drug delivery vehicles. Supplemental Materials are available for this article. Go to the publisher's online edition of Journal of Liquid Chromatography & Related Technologies to view the free supplemental file. [ABSTRACT FROM AUTHOR]