Investigation of the distributional homogeneity on chlorpheniramine maleate tablets using NIR-CI.

Homogeneity is the basic element of pharmaceutical analysis. Distributional Homogeneity Index (DHI) was proposed to assess the distributional homogeneity of commercial chlorpheniramine maleate (CPM) tablets. Furthermore, the divergence value of DHI value from expectation DHI (value = 1) was calculated to obtain the CPM distributional homogeneity. The distribution of commercial CPM tablets from six brands was successfully visualized using near infrared chemical imaging (NIR-CI) coupled with characteristic wavenumber method and binary image. Besides, content homogeneity of CPM was obtained through calculating the proportion of white region in the binary image. The result demonstrated that the distributional homogeneity of brand 4 was to be the best among all the brands, following by brand 2, brand 3, brand 5, brand 6 and brand 1. Furthermore, the sequence of the content uniformity was different from the distributional homogeneity, which demonstrated that content uniformity could not represent the distributional homogeneity. This work was a significant method guideline to assess the distributional homogeneity in pharmaceutical field.

Stereospecific versus nonstereospecific assessments for the bioequivalence of two formulations of racemic chlorpheniramine.

Chlorpheniramine (chlorphenamine, CPAM) is a racemic antihistaminic H1 drug containing two enantiomers. The aim of this study was to assess the bioequivalence of two formulations (reference and Vietnamese-tested formulation) of racemic chlorpheniramine combined with phenylpropanolamine in an open-labeled, randomized, crossover two-period study, after administration of 8 mg of racemic chlorpheniramine in 12 healthy Vietnamese subjects. First, dissolution of both formulations was tested in vitro according to USP requirements. Then the 12 subjects received both formulations after an overnight fast and a 7-day wash-out period. Plasma samples were collected up to 168 h. Plasma concentrations of total chlorpheniramine and its individual enantiomers were determined with a validated chiral HPLC method and pharmacokinetic parameters were estimated using model-independent analysis. For the reference formulation, Cmax and AUC values were higher for (+)S-chlorpheniramine ((+)S-CPAM) compared to (-)R-chlorpheniramine ((-)R-CPAM) (13.3 vs. 6.8 ng/ml and 409 vs. 222 ng/ml/h, respectively) while Clt/F and Vd/F were lower (9.8 vs. 17.6 l/h and 321 vs. 627 l, respectively). No difference was observed for Tmax, t(1/2), and MRT. Pharmacokinetic parameters were similar for the reference and the Vietnamese-tested formulation. Bioequivalence was assessed by Schuirmann test, as recommended by the current FDA and European Community criteria. Dissolution tests showed that both formulations were equivalent. A nonstereospecific, but not a stereospecific, approach indicated bioequivalence between the formulations.

Additive benefits of EFAs in dogs with atopic dermatitis after partial response to antihistamine therapy.

It has been reported that 20 to 70 per cent of atopic cases in the dog can be controlled with antihistamines, though the effective antihistamine cannot be predetermined. Combination therapy with essential fatty acids (EFAs) and antihistamines has been shown to be useful in dogs. All of the work published to date has been performed in open studies, without the use of placebo, and in dogs where the aim has been to control pruritus as a symptom rather than that caused specifically by atopy. The aim of this study was to assess the combined effects of four antihistamines; hydroxyzine, chlorpheniramine, cyproheptadine and clemastine; with both an EFA supplement and a placebo of olive oil, in 25 dogs to control pruritus in clinically proven cses of atopy.