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PubMed1985

Possibilities of liposomes as dynamic dosage form in dermatology.

Local application of substances in different vehicles for the care of the skin and the treatment of skin diseases have been used since antiquity. With the present state of technology a modern dosage form allowing chemical engineering can be devised. Liposomes which consist of lipid bilayers engulfing an aqueous solution fulfill the sophisticated requirements. With a lipid and an aqueous compartment these liposomes can contain lipophilic and hydrophilic medicaments. The lipid composition and the incorporation of charged carrier protein molecules can be varied, affecting the rate of drug release to the skin. In this way active substances are either retained on the skin (pertinent to sunscreening agents) or liberated from the liposome depot to the skin layers (corticosteroids). The highly organized membrane structures containing lysine or hydrolysine can be fixed to the skin enzymatically avoiding temporal removal from the skin and supporting depot function and protective film function. Studying the surface lipid and epidermal lipid composition, lipid membranes can be composed which do not cause hypersensitivity reactions and form a substitute in case of deficient barrier function of the skin.

Dermatologic Agents↗
PubMed1999

Determination of the gastric emptying of solid dosage forms using gamma-scintigraphy: a problem of image timing and mathematical analysis.

This work was designed to identify the maximum time interval of image acquisition by gamma-scintigraphy for monitoring the emptying of a dosage form such as a tablet. Appropriate statistical parameters to describe this process were sought, including a statistical procedure for group comparisons of such data. Gamma-scintigraphy was employed in seven healthy male volunteers, who swallowed a light and a dense tablet, each 12 mm in diameter, formulated to contain different isotopes to allow identification. Images were taken sequentially at 30-s intervals to provide images of each tablet in 1-min spacing until emptying of both tablets was reported. In selecting images, it was also possible to simulate image acquisition intervals of 2, 3, 5, 10, 15, 20 and 30 min. The values derived are discrete random variables. The maximum time interval between image acquisitions that permitted reliable results to be obtained was found to be 3 min for light and 2 min for dense tablets. Consideration of the emptying of a tablet as a Bernoulli random event provided a suitable statistical approach to the analysis of such data, giving a median and an interquartile range. While the commonly applied method, which is based on parametric procedures deriving arithmetic means and standard deviations, failed to detect a difference in the emptying times of the two types of tablets, the use of non-parametric statistics (Wilcoxon test) provided a clear distinction between them in this respect. The assessment of gastric emptying by gamma-scintigraphy studies can be improved by using short image intervals and application of appropriate statistical analysis.

Adult↗
PubMed1991

Dosage forms of cyclosporine.

Cyclosporine can be given intravenously or orally, as a solution or soft gelatin capsule. Because of the drug's poor water solubility, ethoxylated plant fats and ethanol are added to the commercially available dosage forms.

Administration, Oral↗
PubMed2001

Development of polymer film dosage forms of lidocaine for buccal administration. I. Penetration rate and release rate.

We examined the penetration rate of lidocaine (LC) through excised oral mucosa from hamster cheek pouch and the in vitro release rate of LC from film dosage forms with hydroxypropylcellulose (HPC) as a film base. Addition of glycyrrhizic acid (GL) to the HPC films increased the LC release rate almost GL-content-dependently, while an optimum GL content was observed for the LC penetration rate. No LC penetration was observed from an acidic aqueous solution (pH 3.4) of LC, suggesting only unionized LC can substantially penetrate through the mucosa. A significant relationship between the penetration rate of LC and the release rate of unionized LC was found, suggesting that the in vitro dissolution study is a useful tool to predict the penetration rate taking the unionized drug fraction into consideration.

Administration, Buccal↗
PubMed2001

[Evaluation of efficacy of ramosetron orally disintegrating tablets and patient preference as to the dosage form in gynecological cancer chemotherapy].

The efficacy of an oral 5-HT3 antagonist, ramosetron orally disintegrating tablet (ODT), in the treatment of chemotherapy-induced emesis was investigated in 21 female patients with cancer. Patient preference for the dosage form was also investigated. Eighteen (85.7%) of 21 patients answered that ODT is easy to take. Eleven (68.8%) of 16 patients who had previously taken granisetron tablets preferred ramosetron ODT to conventional tablets. The complete suppression rate of nausea or vomiting was more than 90% for 6 days. No adverse drug reactions associated with ramosetron were observed. As ambulatory or home chemotherapy becomes frequent, the use of oral 5-HT3 antagonists rather than intravenous agents will be increased. Chemotherapy for elderly cancer patients is becoming frequently used. Considering these circumstances, it is suggested that ramosetron ODT is a palatable and useful treatment of chemotherapy-induced emesis.

Administration, Oral↗
PubMed2005

A simple spectrophotometric method for the determination of beta-blockers in dosage forms.

A simple, extraction-free spectrophotometric method is proposed for the analysis of some beta-blockers, namely atenolol, timolol and nadolol. The method is based on the interaction of the drugs in chloroform with 0.1% chloroformic solutions of acidic sulphophthalein dyes to form stable, yellow-coloured, ion-pair complexes peaking at 415 nm. The dyes used were bromophenol blue (BPB), bromothymol blue (BTB) and bromocresol purple (BCP). Under the optimum conditions, the three drugs could be assayed in the concentration range 1-10 microg ml(-1) with correlation coefficient (n = 5) more than 0.999 in all cases. The stoichiometry of the reaction was found to be 1:1 in all cases and the conditional stability constant (K(F)) of the complexes have been calculated. The free energy changes (DeltaG) were determined for all complexes formed. The interference likely to be introduced from co-formulated drugs was studied and their tolerance limits were determined. The proposed method was then applied to dosage-forms the percentage recoveries ranges from 99.12-100.95, and the results obtained were compared favorably with those given with the official methods.

Adrenergic beta-Antagonists↗
PubMed2003

Rapid, noninvasive quantitative determination of acyclovir in pharmaceutical solid dosage forms through their poly(vinyl chloride) blister package by solid-state Fourier transform Raman spectroscopy.

Fourier transform (FT) Raman spectroscopy based on band intensity or band area measurements was used for the quantitative determination of acyclovir in pharmaceutical solid dosage forms through their poly(vinyl chloride) blister package. Univariate calibration using the bands observed at 1690, 1630, 1574, 1482, 1181, 578, and 508 cm(-1) was found to be sufficient for the analysis. Calibration curves were linear, the correlation coefficients being 0.997-0.9993 and 0.996-0.9991 for band intensity and band area measurements, respectively. Results obtained compare well, as indicated by the t-test, with those obtained by the current United States Pharmacopoeia (USP 24) and National Formulary (NF 19) method. Precision ranged from 0.7-4.5 and 0.4-4.0% RSD (n = 3) for band intensity and band area measurements, respectively. The developed nondestructive FT-Raman method is rapid, simple, and can be used for the on-line, real-time monitoring of acyclovir formulation production lines.

Acyclovir↗
PubMed1999

Development and evaluation of a multiple-unit oral sustained release dosage form for S(+)-ibuprofen: preparation and release kinetics.

Mini-matrix tablets containing S(+)-ibuprofen have been prepared by the wet granulation method. The hydrophilic matrix was formed with either xanthan gum, karaya gum or hydroxymethylcellulose (HPMC) together with a choice of additives from lactose, Encompress(R), Avicel(R) PH101, talc and Lubritab(R). Multiple unit dosage forms (MUDFs) were subsequently obtained by encapsulating the mini-matrix tablets into hard gelatin capsules. Preparation, in vitro release profiles and release kinetics are presented.

Capsules↗
PubMed2005

Development and validation of a reversed-phase HPLC method for the determination of ezetimibe in pharmaceutical dosage forms.

Ezetimibe belongs to a group of selective and very effective 2-azetidione cholesterol absorption inhibitors that act on the level of cholesterol entry into enterocytes. A rapid, specific reversed-phase HPLC method has been developed for assaying ezetimibe in pharmaceutical dosage forms. The assay involved an isocratic elution of ezetimibe in a Kromasil 100 C18 column using a mobile phase composition of water (pH 6.8, 0.05%, w/v 1-heptane sulfonic acid) and acetonitrile (30:70, v/v). The flow rate was 0.5 ml/min and the analyte monitored at 232 nm. The assay method was found to be linear from 0.5 to 50 microg/ml. All the validation parameters were within the acceptance range. The developed method was successfully applied to estimate the amount of ezetimibe in tablets.

Acetonitriles↗
PubMed1990

Application of radiotelemetric technique in evaluating diclofenac sodium absorption after oral administration of various dosage forms in healthy volunteers.

A radiotelemetric technique with the Heidelberg capsule (HC) was used to improve the quality of data generated in a bioavailability study involving an enteric-coated (EC) formulation. Further, changes in plasma levels of the drug from other dosage forms were related to changes in pH environment as determined by the HC. Eight healthy male subjects received the following treatments, 15 min after a light breakfast, according to a randomized, four-way crossover design: (A) HC and 75 mg of a diclofenac sodium aqueous buffered solution: (B) HC and one 75-mg Voltaren EC tablet; (C) HC and one 100-mg Voltaren slow-release (SR) tablet; and (D) HC alone. Each treatment was separated by a 1-week washout period. Two additional subjects subsequently received Treatment B only. Multiple peaks were observed in the drug plasma level-time profiles for the buffered aqueous solution which, in all cases, occurred before gastric emptying of the HC. The multiple peaks were not observed for the Voltaren SR tablet, but a variable absorption lag time occurred which coincided with the gastric residence time of the SR tablet. For the EC tablet the variability of individual plasma level-time profiles was drastically reduced when the time after dosing was adjusted to coincide with gastric emptying of the HC. Finally, the lag time between gastric emptying of the EC tablet and the onset of drug absorption was consistently at 1 hr for all subjects. This lag time was longer than the in vitro disintegration or dissolution times measured under USP conditions.

Administration, Oral↗
PubMed1990

Gastro-intestinal absorption of ethyl 2-chloro-3-[4-(2-methyl-2-phenylpropyloxy)phenyl]propionate from different dosage forms in rats and dogs.

To obtain information as to a suitable formulation of ethyl 2-chloro-3-[4-(2-methyl-2-phenylpropyloxy)-phenyl]propionate (AL-294), an antihyperlipidemic drug of low water solubility, the bioavailability after its oral administration in various dosage forms was evaluated in rats and dogs. After AL-294 was administered orally, AL-294 acid (2-chloro-3-[4-(2-methyl-2-phenylpropyloxy)phenyl]propionic acid), which is a metabolite of AL-294, was detected in the plasma. Therefore, absorbability of AL-294 was evaluated using plasma AL-294 acid levels. AL-294 in an oil solution or in a gelatin capsule showed poor absorption, whereas it's absorption was greatly enhanced in the form of an emulsion. The postprandial administration also showed better absorption. The elimination rate of AL-294 acid from the plasma after oral administration of the emulsion was similar to that after intravenous administration of a sodium salt of AL-294 acid.

Animals↗
PubMed2003

Novel levodopa gastroretentive dosage form: in-vivo evaluation in dogs.

Due to its narrow absorption window, levodopa has to be administered continuously to the upper parts of the intestine in order to maintain sustained therapeutic levels. This may be achieved by a controlled release (CR) gastroretentive dosage form (GRDF). The aim of this work was to develop a novel GRDF, based on unfolding polymeric membranes, that combines extended dimensions with high rigidity, and to examine the pharmacokinetics of levodopa compounded in the GRDF. Levodopa CR-GRDFs were administered to beagle dogs pretreated with carbidopa. The CR-GRDF location in the gastrointestinal tract was determined by X-ray, and serial blood samples were collected and assayed for levodopa. Optimization of the pharmacokinetic profile of levodopa from the CR-GRDFs was carried out based on the in-vitro in-vivo correlation following modifications of the release rates (adjusted by various membrane thicknesses) and drug loads. The successful CR-GRDF maintained therapeutic levodopa concentrations (>500 ng ml(-1)) over 9 h. In comparison to non-gastroretentive CR-particles and oral solution, mean absorption time was significantly extended. These outcomes demonstrate that the CR-GRDF may be used to improve levodopa therapy and can be applied to extend the absorption of other narrow absorption window drugs that require continuous input.

Administration, Oral↗