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This study introduces fluocinolone acetonide (FA) microemulsion in combination with ablative fractional lasering as a new effective treatment for scalp psoriasis. A pseudo-ternary phase diagram was constructed using the aqueous titration method. The suitable ratio of surfactant mixture (S

This work reports on the solubility of two weakly basic model compounds in media containing sodium lauryl sulfate (SLS). Results clearly show that the presence of SLS in the media (e.g. simulated gastric fluid or dissolution media) can result in an underestimation of solubility of some weak bases. We systematically study this phenomenon and provide evidence (chromatography and pXRD) for the first time that the decrease in solubility is likely due to formation of a less soluble salt/complex between the protonated form of the weak base and lauryl sulfate anion.

In an attempt to investigate how a nonionic polymer, hydroxypropyl methylcellulose (HPMC), interacts with a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), a dialysis method was employed for directly measuring the HPMC–CTAB interaction. The result showed that an interaction existed between CTAB and HPMC, and the higher the HPMC concentration the greater the fraction of CTAB bound. The shift in the UV spectra represents the change in the microenvironment. UV spectroscopy was employed to indicate the location of substrates, α‐NA, IBA, and oil red O, in the CTAB micelles. The study of solubility as a function of CTAB concentration was the method used for determining the binding constants of the substrates. The addition of HPMC decreased the binding constants of the substrates to the micelles. It implied that the HPMC‐CTAB interaction influenced the substrate binding regions. The IBA binding constant was also determined using a potentiometric titration method. The results agreed well between the two methods. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1440–1451, 2010

OBJECTIVES To compare the pharmacokinetic profile of ceftiofur hydrochloride (ceftiofur) administered intramuscularly at 3 mg/kg body weight (BW) in pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV) versus clinically healthy pigs. METHODS Sixteen 3- to 4-week-old PRRSV-negative pigs were randomly assigned to two groups (A and B), with eight pigs per group. Pigs in Group A were uninfected controls and pigs in Group B were intranasally challenged with a PRRSV isolate of Thai origin. Pigs in both groups were intramuscularly administered ceftiofur at 3 mg/kg BW at 7 days post-infection. Blood samples were serially collected up to 72 h post-injection. Plasma was analysed for ceftiofur and its related metabolites using HPLC. Pharmacokinetic parameters of ceftiofur were calculated based on non-compartmental analysis. RESULTS Pharmacokinetic parameters of ceftiofur revealed statistically significant differences (P < 0.01) in maximum concentration (C(max)), AUC, volume of distribution at the terminal phase over bioavailability (V(z)/F), clearance over bioavailability (CL/F) and the terminal half-life (t(1/2z)) between Groups A and B. PRRSV-infected pigs had a V(z)/F and CL/F of ceftiofur significantly higher than in the non-infected pigs (116% increase in V(z)/F, 234% increase in CL/F). The C(max) and AUC of the infected pigs decreased by 54% and 70%, respectively, compared with the non-infected pigs. The t(1/2z) of the infected pigs and the non-infected pigs was 13.1 and 21.0 h, respectively. CONCLUSIONS The pharmacokinetic profile of ceftiofur is altered in PRRSV-infected pigs due to the decreased plasma ceftiofur concentration compared with clinically healthy pigs.

The change in the hexadecyltrimethylammonium bromide (CTAB) critical aggregation concentration (CAC) was studied in the presence of various concentrations and grades of hydroxypropylmethyl cellulose (HPMC) using surface tension measurement (duNouy ring and Wilhelmy plate) and oil red O solubilization. According to the surface tension methods, the CAC was higher than the CTAB critical micelle concentration (CMC). CAC and CMC were not different when the solubilization method was used. Micellar solutions of CTAB have been found to accelerate the hydrolysis of α-naphthyl acetate (α-NA) by o-iodosobenzoic acid (IBA), a strong nucleophile. Pseudo-first-order kinetics were utilized for rate constant determination. The observed rate constants for the degradation of α-NA in the presence of varying CTAB concentrations with and without HPMC were analyzed according to the pseudophase model. The micellar rate constants and the micellar binding constants for the substrates were obtained. The presence of HPMC retarded the reaction rate, and the rate constant decreased as the polymer concentration increased. However, there was no obvious difference in the observed rate constants among the different grades of HPMC (Methocel E5®, Methocel E15®, Methocel E50®). The decrease in the rate constant was likely due to the polymer–micelle interaction interfering with substrate binding to the CTAB micelles. ©2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 96:448–458, 2007

Micelle formation is an important property of surfactants. Micellar solutions of cetyltrimethylamonium bromide (CTAB) have been found to accelerate the hydrolysis of alpha-naphthyl acetate (alpha-NA) by o-iodosobenzoic acid (IBA), a strong nucleophile. Critical micelle concentration (CMC) of CTAB was determined in the absence and presence of various concentrations and grades of hydroxypropylmethyl cellulose (HPMC) using surface tension measurement. Reaction under pseudo-first-order condition was utilized for rate constant determination. The aggregation of CTAB in the polymer solution started at higher concentration than in the absence of the polymer. The observed rate constants for the degradation of alpha-NA in the presence of various concentrations of CTAB with and without HPMC were calculated. The presence of HPMC retarded the reaction rate. However, there was no obvious difference in the observed rate constant among the different grades of HPMC (Methocel E50, Methocel E4M, Methocel E10M) while the higher the polymer concentration the lower the rate constant.