Application of reverse-flow micellar electrokinetic chromatography for the simultaneous determination of flavonols and terpene trilactones in Ginkgo biloba dosage forms

A reverse-flow micellar electrokinetic chromatographic (RF-MEKC) method was developed for the simultaneous qualitative determination of 10 components consisting of the flavonol glycosides, rutin and quercitrin, the flavonol aglycones, isorhamnetin, kaempferol and quercetin, the terpene trilactones, ginkgolides A, B, C and J and the sesquiterpene, bilobalide. This method was used to fingerprint Ginkgo biloba solid oral dosage forms and validated for the quantitation of the marker compounds, rutin and quercetin in some commercial products. In addition to the usual variables, the influence of some essential background electrolyte (BGE) components such as sodium dodecyl sulphate (SDS) and -cyclodextrin concentrations were investigated. A polyimide fused-silica square capillary column (75 μm I.D. × 360 μm O.D.) with a total length of 60.0 cm and effective length of 45.0 cm was used for the separation. The final BGE consisted of 20 mM phosphoric acid, 40 mM SDS and 12 mM -cyclodextrin (pH 2.2) using reverse polarity with a voltage of −17.5 kV. Samples were injected electrokinetically at −5 kV for 3 s for the qualitative analysis and hydrodynamically at 20 mbar for 0.6 s for the quantitative assay. The total run time was 22 min and the limits of detection were 3.13 μg/ml and 1.88 μg/ml for rutin and quercetin, respectively. Fingerprint profiles of the solid oral dosage forms and the results of the quantitative analysis indicated that there were major discrepancies in the marker content between products and illustrates the value of this method for use as a procedure to assess product quality of commercially available Ginkgo biloba products

Assessment of topical corticosteroid preparations: the human skin-blanching assay

(From the introduction) Since the introduction of topical corticosteroid formulations, their use has become widespread, being prescribed for a large variety of dermatological conditions. This widespread use has created a need for a reliable method of assessing the various dosage forms of these compounds. Clinical trials are laborious, costly and difficult to mount as well as being impractical for the screening of large numbers of drugs. Patients suffering from dermatological complaints are not ideal subjects for the testing of topical corticosteroid preparations as it is difficult to obtain standardized lesions which are necessary for the comparison of results between patients (Baker and Sattar, 1968). For these reasons a number of methods have been developed for the screening of novel corticosteroids and testing of topical corticosteroid formulations

Comparative bioavailability of some locally manufactured betamethasone valerate containing preparations

The bioavailabilities of three locally manufactured proprietary betamethasone- 17-valerate containing creams and ointments were compared by measuring their abilities to cause blanching of human skin after topical application. The preparations studied were Betnovate Cream and Ointment, Celestoderm-V Cream and Ointment and Persivate Cream and Ointment. Celestoderm-V cream displayed a significantly superior blanching activity over both Betnovate and Persivate creams in' the occluded mode, whereas Persivate cream displayed a significantly superior blanching activity over both Betnovate and Celestoderm-V creams in the unoccluded mode. Persivate ointment was found to produce a significantly superior blanching activity over Betnovate and Celestoderm-V ointments in both the occluded and unoccluded modes of application

Phenylpropanolamine hydrochloride

Phenylpropanolamine hydrochloride belongs to the sympathomimetic amine class of drugs and is structurally related to ephedrine hydrochloride. Its synthesis was first reported in 1910 and the first American patent was registered in 1939. The effects of phenylpropanolamine hydrochloride are largely the result of alpha-adrenergic agonist activity resulting from both direct stimulation of adrenergic receptors and release of neuronal norepinephrine. The principal adverse effect of phenylpropanolamine hydrochloride is dose-related hypertension and ventricular arrhythmia has been described. Phenylpropanolamine hydrochloride is widely used as a decongestant and it has been used as an anorectic agent for over 40 years. A report in 1939 described its effect as an hypertensive agent when administered parenterally

Pharmacokinetics of phenylpropanolamine in humans after a single dose study

The pharmacokinetics of phenylpropanolamine have been studied in healthy human volunteers following the oral administration of an aqueous solution of the drug (50 mg/200 ml). Blood and urine samples collected throughout the trial were assayed using HPLC with UV detection. The drug was shown to be rapidly absorbed with a mean tmax of 1.47 ± 0.49 h and a mean elimination half-life of 4.0 ± 0.5 h. Phenylpropanolamine is predominantly excreted via the kidney with a mean renal clearance of 0.646 ± 0.089 liter/kg/h and 90.2 ± 1.7% excreted unchanged in the urine. The data were not well described using conventional one or two body compartment models. However, the incorporation of a discontinuous absorption phase into the models resulted in an improved overall fit with better characterisation of the absorption phase

Comparative blanching activities of some topical corticosteroid containing lotions

The blanching activities of Betnovate and Celestoderm-V lotions (betamethasone-17-valerate, 0,1%) and Diprosone lotion (betamethasone dipropionate, 0,55%) were determined by measuring their ability to cause blanching of human skin after topical application. Betnovate and Celestoderm-V lotions produced almost identical blanching profiles. Diprosone lotion displayed a statistically significant superior blanching acitivity over both Betnovate and Celestoderm-V lotions over the whole timespan of the trial

In vitro-in vivo evaluation of a sustained release phenylpropanolamine oral dosage form

There is increasing interest in measuring pharmacokinetic parameters of phenylpropanolamine (PPA), a sympathomimetic amine used in over-the-counter nasal decongestants and anorectic formulations. A high pressure liquid chromatographic (HPLC) procedure was developed to enable direct ultraviolet detection of PPA, after extraction from serum and urine, without prior derivatization of the drug. This method was used to assay samples obtained from a bioavailability study of BUBtained-releasePPA tablets. The mean serum and urine profiles obtained are presented. The sustained-release tablets were subjected to dissolution testing utilizing the United States Pharmacopoeia (USP XIX) rotating basket method. An internal standard was incorporated into the dissolution fluid to enable direct analysis of the samples by HPLC. A comparison of three different dissolution fluid regimens was carried out to determine if release of the drug was affected by the change in pH of the medium and to select the most convenient method for the final dissolution studies. Some preliminary observations relating to correlations between rate of drug release from the sustained-release dosage form and percent drug absorbed are presented

Determination of phenylpropanolamine in serum and urine by high performance liquid chromatography

A high-performance liquid chromatographic analysis of phenylpropanolamine in human serum and urine without prior derivatization is presented. Using direct UV detection the method is sufficiently sensitive to detect 25 ng of drug/ml of serum or urine; the coefficients of variation at 25 ng/ml and 500 ng/ml were 5.16 and 2.12, respectively, in serum. The method involves serum and urine extraction at a basic pH with chloroform, a single back-extraction, and chromatography on a reverse-phase column. Serum and urine data following administration of a single 150-mg sustained-release tablet of phenylpropanolamine hydrochloride in 6 healthy volunteers demonstrates the suitability of the analytical method

Determination of erythromycin in serum and urine by high performance liquid chromatography with ultraviolet detection

A high-performance liquid chromatographic analysis of erythromycin in human serum and urine with UV detection at 200 nm is presented. The method involves a solid-phase extraction procedure followed by a simple phase separation step and chromatography on a reversed-phase column. The method has sensitivity limits of 0.25 and 1.0 g/mL in serum and urine, respectively, and is sufficiently sensitive to monitor concentrations of erythromycin in human serum and urine after the administration of a single 500-mg erythromycin stearate tablet

Assessment of some variables affecting the blanching activity of betamethasone 17-valerate cream

The effect of concentration and occlusion time on the ability of Betnovate ® cream (betamethasone 17-valerate 0.1%) to produce skin blanching was assessed. Generally, increased concentration or occlusion time produce and increase in the degree of blanching observed, however, a plateau stage is eventually reached where no further increase of blanching occurs