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At least 343 records · Page 19Linked to original sources

PubMed1994

Release profiles of phenytoin from new oral dosage form for the elderly.

Utilization of the solid mass containing phenytoin, sodium caseinate and microcrystalline cellulose (MCC) as a new dosage form for the elderly was studied. The solid mass was prepared by treatment of the powder mixture with high pressure steam at 115 degrees C for 10 min. The stability of phenytoin in the solid mass was confirmed by infrared spectroscopy and high performance liquid chromatography. The extent of swelling of the solid mass containing phenytoin was investigated by water absorption test and gel strength test, and the swelling property was almost independent of the presence of phenytoin. The release profile of phenytoin from the solid mass was determined under various conditions, and was found to be influenced by the extent of swelling and the swollen state. It was observed that the protein adsorption to the phenytoin crystal surface and the addition of digestive enzyme also affected the release profile. In water, the solid mass prepared from a ground mixture of phenytoin and MCC showed remarkable improvement of release profile of phenytoin.

Absorption↗

PubMed2000

Peroral administration of enzymes: strategies to improve the galenic of dosage forms for trypsin and bromelain.

In this study, we investigated the presystemic metabolism of trypsin and bromelain and the influence of these proteolytic enzymes on the mucus layer covering the gastrointestinal (GI) epithelia. In vitro studies demonstrated that 77.3% +/- 4.0% (mean +/- SD, n = 3) of trypsin is autodegraded within 2 hr, whereas autodegradation of bromelain was negligible. In contrast to the metabolization of bromelain by all pancreatic serine proteases, trypsin is only degraded to some extent by elastase. Both therapeutically used enzymes remained stable after incubation with an excised porcine mucosa, demonstrating that proteolysis caused by brush border membrane-bound enzymes is negligible. Trypsin and bromelain were highly mucolytic active, thereby reducing the diffusion barrier based on the mucus gel layer. Strategies to improve the galenic of dosage forms for trypsin and bromelain include the use of bioadhesive polymers such as hydroxyethylcellulose or slightly modified chitosan-EDTA, providing strongly improved stability of these enzymes toward proteolytic degradation in vitro. The given information represents a good starting point to improve the galenic of dosage forms for orally administered proteolytic enzymes.

Administration, Oral↗

PubMedDate not supplied

Determination of chlorpheniramine maleate and tincture ipecac in dosage form by liquid chromatography with ultraviolet detection.

A procedure was developed and validated for measuring chlorpheniramine maleate and tincture ipecac (as emetine hydrochloride) by reversed-phase liquid chromatography with methanol-10 mM sodium heptanesulfonate (20 + 30) as the mobile phase; the pH was adjusted to 4 with acetic acid, and the flow rate was at 1.5 mL/min, with ultraviolet detection at 254 nm. Propyl paraben was used as the internal standard. The standard curves were linear (r = 0.998 and 0.9998) for both chlorpheniramine maleate and emetine hydrochloride over the ranges of 5-100 and 0.1-40 microg/mL, respectively. The mean recoveries +/- standard deviation were 101.37 +/- 2.77% for chlorpheniramine maleate and 98.8 +/- 1.47% for emetine hydrochloride. The proposed method was applied to the determination of chlorpheniramine maleate alone in tablet and syrup dosage forms. The method also was applied to the determination of the emetine content of ipecac liquid extract and tincture ipecac; the results were compared with those of the method of the British Pharmacopoeia. The proposed method was applied successfully to the simultaneous determination of chlorpheniramine maleate and tincture ipecac, as emetine hydrochloride, in syrup dosage form. Both drugs and the internal standard were separated from all interfering components in < 5 min. The proposed method is simple, specific, and economical, when compared with other published methods that determine each component alone.

Chlorpheniramine↗

PubMed1993

Regulatory aspects of modified release dosage forms: special cases of dissolution testing using the flow-through system.

More than 30 years have been devoted to characterizing the biopharmaceutical properties of drug products. The numerous tests developed are generally based on two distinct methodologies--a closed system (beaker method) and an open system (flow-through method). Selected methods were finally standardized and described in such pharmacopoeias as Ph. Eur. 2, USP XXII and Ph. Jap. XII. The most common procedures are the paddle and basket methods. An alternative method--the flow--through method--was also introduced into the pharmacopoeias Ph. Eur. 2 and USP XXII. The advantages of the flow-through method are evident with regard to testing and assessing different types of dosage forms and active ingredients of very slight solubility. Changes of testing fluids (e.g. change to the pH) can be easily performed during the test. Another advantage is seen in the positioning of the specimen. Capsules, even when floating initially, or pellets can be tested using the same equipment and require no additional devices such as sinkers. With slight changes to the cell design, the same apparatus can be used for the testing of powders, or even non-solid dosage forms such as suppositories or soft-gelatine capsules. For long-term testing necessary for extended release products, flow-through apparatus offers a considerable number of advantages for routine work. Irrespective of the methodologies used, dissolution tests should be validated with regard to analytical methods, testing conditions and specifications. The validation of the analytical method should follow EC guidelines. Testing conditions should take into account the choice of the correct apparatus, dissolution media and agitation. The results of in vitro dissolution should be validated by in vivo data in an analogous sense. The practical application of flow-through apparatus is presented on the basis of various examples regarding development and batch control. The assessment of in vitro dissolution of biopharmaceutical characterization of drug substances, enteric-coated tablets, controlled release products, suppositories and implants will be discussed.

Biopharmaceutics↗

PubMed1984

Quantitation of phenobarbital and phenobarbital sodium in pharmaceutical dosage forms.

A reverse-phase high-performance liquid chromatographic method for the quantitation of phenobarbital and phenobarbital sodium in pharmaceutical dosage forms (elixir, injection, and tablets) was developed. The method is precise and accurate with percent relative standard deviations of 0.9 (without an internal standard) and 0.7 (with an internal standard) based on six injections. The method is stability indicating and is more sensitive than the revised USP-NF method. The products of decomposition showed two new peaks in the chromatogram.

Chromatography, High Pressure Liquid↗

PubMed2001

A stability-indicating LC method for the simultaneous determination of ramipril and hydrochlorothiazide in dosage forms.

A simple, rapid and sensitive HPLC method has been developed for the simultaneous determination of ramipril and hydrochlorothiazide in their dosage forms. Acetonitrile: sodium perchlorate solution (0.1 M) adjusted to pH 2.5+/-0.2 with phosphoric acid (46:54 v/v), was used as the mobile phase, at a flow rate of 1.5 ml/min. A supelcosil LC-8 column (5 microm), 15 cm x 4.6 mm i.d. was utilized as stationary phase. Detection was affected spectrophotometrically at 210 nm. Clobazam was used as an internal standard. The method was also applied for the determination of ramipril in the presence of its degradation products. Linearity ranges for ramipril and hydrochlorothiazide were 4.5-45 and 0.6-14 microg/ml, respectively. Minimum detection limits (S/N = 2) obtained were 180 and 23 ng/ml for ramipril and hydrochlorothiazide, respectively. The proposed method was further applied to the analysis of tablets containing the two drugs, the percentage recoveries +/- S.D. (n = 5) were 100.45%+/-0.63 and 99.55%+/-0.78 for ramipril and hydrochlorothiazide, respectively.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Optimization of two flow-injection spectrophotometric methods for the determination of indapamide in pharmaceutical dosage forms.

Multivariate experimental design has been used to optimize 2 flow-injection spectrophotometric methods for the determination of indapamide in pharmaceutical dosage forms, both pure and commercial tablets. The methods are based on the oxidation of this drug with iron (III) in acidic medium and the subsequent formation of an intensive orange-red complex between the liberated iron (II) and 2,2'-bipyridyl or 1,10-phenanthroline reagents. Plackett-Burman designs were applied as a screening method to evaluate the most significant factors with few experiments. Central composite 2(3)+ star designs were performed to evaluate the response surfaces. The methods have been fully validated and were applied successfully to the determination of indapamide in pure and pharmaceutical forms with good accuracy and precision. Therefore, the 2 proposed procedures are simple, inexpensive, and rapid flow methods for the routine determination of indapamide in pharmaceutical preparations.

Antihypertensive Agents↗

PubMed2004

The rationale of scored tablets as dosage form.

The aim of the study was to get insight into the rationale of scored tablets. This was pursued by studying patient's reasons for subdividing ("breaking") scored and unscored tablets. Patients who picked up their prescriptions in 5 community pharmacies in The Netherlands were questioned. Two-hundred and seventy-five prescriptions were studied. Of all dispensed tablets, 31% were subdivided, mostly because a dose that needed subdivision was prescribed. However, 30% were subdivided upon the initiative of the patient himself: 13% for ease of swallowing and 17% because the patient chose to take a lower dose. Even unscored tablets were subdivided: because the dose prescribed was half the tablet dose (6%), for ease of swallowing (1%) and the wish of the patient to take a lower dose (3%). It was also inquired about the patient's perception of the ease of subdivision of scored tablets. Problematic subdivision of scored tablets was reported in 55% of the cases, 42% of which was attributed to a disfunctioning score line. We also studied the possibility to prescribe and dispense other medicinal products as alternatives for tablets that needed to be subdivided. For 46% a dosage form with a lower dose was on the market, for 54% it was not. We conclude that scored tablets still fulfil an important role. Even when lower dosed tablets would become available, there remains a substantial wish of patients to subdivide tablets for ease of swallowing and adapting the dose. Improving the functioning of score lines may be a more practical approach than banning this dosage form.

Administration, Oral↗

PubMedDate not supplied

Relative bioavailability of three commercial quinidine dosage forms.

Bioavailabilities of three quinidine formulations were compared. Two tablets of each dosage form were administered to 12 healthy volunteers according to a repeated Latin square design; plasma levels of unchanged and total drug were determined. Quinidine was absorbed significantly more rapidly from one of the formulations than the other two; the bioavailability of this formulation, calculated from intact drug data, normalized for subject differences, was also significantly greater than that of the other two, 68 and 76 per cent respectively. Individual comparisons of area under the curve (AUC) indicated that estimated relative bioavailability depends on the specificity of the assay, the adjustment of the AUC for the area beyond the last measurable plasma concentration and the normalization of the AUC. The data suggest there is a correlation between dissolution rate and peak plasma concentration.

Adult↗

PubMed1984

Stabilized normal-phase high-performance liquid chromatographic analysis of aspirin and salicylic acid in solid pharmaceutical dosage forms.

A simultaneous analysis of aspirin and nonaspirin salicylates in solid pharmaceutical dosage forms is described. Two separate extraction procedures are employed, one for plain aspirin tablets and one for tablets containing aspirin plus buffers or antacids. The analyses of the extracted samples are accomplished by a stabilized normal-phase high-performance liquid chromatographic (HPLC) procedure. Prepared samples and standards are stable for up to 24 h, and the methodology is suitable for an automated HPLC system.

Antacids↗

PubMed2005

Citric acid prolongs the gastro-retention of a floating dosage form and increases bioavailability of riboflavin in the fasted state.

A floating dosage form based on calcium alginate beads has been developed. Riboflavin, was selected as the model drug and successfully incorporated into calcium alginate beads. The aims of the current study were to: (a) assess the influence of prolonged gastro-retention on the bioavailability of riboflavin from freeze dried calcium alginate beads administered under varying conditions of food intake and (b) to investigate the potential of citric acid to delay the gastric emptying of the calcium alginate beads. Gamma scintigraphy was selected as the method to monitor the movement of the calcium alginate beads in vivo. Riboflavin concentrations in the urine were analysed by HPLC. Prolonged gastro-retention can be achieved, in the fasted state, when citric acid solution is used as an administering vehicle. However, prolonged gastro-retention is not achieved to the same extent when the gastric emptying times are compared to those obtained in the fed state. The bioavailability of riboflavin improved when calcium alginate beads were administered in the fasted state with citric acid solution, compared to the bioavailability obtained when the calcium alginate beads were administered in the absence of citric acid.

Adult↗

PubMedDate not supplied

Formulation development of frozen parenteral dosage forms.

Many of the intravenously administered drug compounds are formulated as frozen dosage forms due to lack of sufficient chemical stability at room or refrigerated temperatures. The product is stored in a freezer in the hospital pharmacy and thawed prior to its use. These products therefore, require a long-term frozen shelf-life plus a short-term room temperature and/or refrigerated temperature shelf-life. The formulation is optimized for overall stability in the frozen state as well as in the thawed state. In this paper, the significance of phase changes in the frozen state and the influence of various formulation factors such as drug concentration, diluent, buffer concentration, pH, and raw material purity on the drug stability in the frozen state is reviewed. An overview of analytical and manufacturing considerations unique to frozen products is also presented.

Buffers↗

PubMedDate not supplied

Preclinical development and characterization of an intravenous dosage form for the ACE inhibitor RS-10029.

Preclinical development of an intravenous dosage form for the ACE inhibitor RS-10029 involved the formulation and characterization of the drug's chemical/physical stability in two prototype formulations (injectable solution and lyophilized powder). Included in these studies were quantitative evaluations of various processing and administration parameters (membrane qualification, terminal sterilization, compatibility/delivery of the drug with typical infusion fluids and administration sets) on finished product integrity and quality. Analytical methodology used in these studies consisted primarily of a stability specific HPLC assay and a light obscuration based sensor (HIAC) for particulate matter analysis. Results of these studies indicate that the drug is relatively stable at ambient temperature and under accelerated storage conditions (predicted T90 at 25 degrees C greater than 2 yr, and T90 at 50 degrees C greater than 2 mo). However, the ability of the product to withstand a full terminal sterilization cycle is limited, and therefore other approaches toward sterile processing were examined. With regard to the stability and compatibility of the drug in a variety of fluids and devices there appears to be no overt limitations in its use for either bolus or infusion delivery.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2002

Determination of lovastatin and simvastatin in pharmaceutical dosage forms by MEKC.

A micellar electrokinetic chromatographic (MEKC) method was developed for the quantification of lovastatin and simvastatin, cholesterol lowering agents in pharmaceutical dosage forms. Lovastatin and simvastatin were separated using an electrolyte system consisting of 12% acetonitrile (v/v) in 25 mM sodium borate buffer pH 9.3 containing 25 mM sodium dodecyl sulphate (SDS) with an extended light path capillary (48.5 cm x 50 microm i.d, 40 cm to detector). The method has been validated and proven to be rugged. Calibration curves were linear over the studied ranges with correlation coefficients greater than 0.996. A limit of detection of 3.2 microg/ml and a limit of quantitation of 10.6 microg/ml were estimated for both the drugs. The proposed method was found to be suitable and accurate for the determination of these drugs in commercial formulations.

Acetonitriles↗

PubMed1966

Pangamic acid (vitamin B 15, pangametin, sopangamine): Its composition and determination in pharmaceutical dosage forms.

Pangamic acid is shown to be a mixture of variable composition. Criteria of identity and methods of analysis are described for five pharmaceutical dosage forms. Experimental results indicate that the products are not uniform in composition and that composition does not conform to label claims. No satisfactory preclinical drug application for any such preparation has so far been submitted to the Food and Drug Directorate.

Dosage Forms↗

PubMed2004

Simultaneous high-performance liquid chromatographic determination of pioglitazone and metformin in pharmaceutical-dosage form.

A simple, rapid, and precise method is developed for the quantitative simultaneous determination of metformin and pioglitazone in a combined pharmaceutical-dosage form. Separation is achieved with a Zorbax XDB C(18), 15-cm analytical column using buffer-acetonitrile (66:34, v/v) of pH 7.1, adjusted with orthophosphoric acid as the mobile phase. The buffer used in the mobile phase contains 10mM disodium hydrogen phosphate and 5mM sodium dodecyl sulphate in double-distilled water. The instrumental settings are flow rate of 1 mL/min, column temperature at 40 degrees C, and detector wavelength of 226 nm. The internal standard method is used for the quantitation of the ingredients of this combination. Methylparaben is used as an internal standard. The method is validated and shown to be linear for metformin and pioglitazone. The correlation coefficients for metformin and pioglitazone are 0.9991 and 0.9999, respectively. The relative standard deviations for six replicate measurements in two sets of each drug in the tablets are always less than 2%.

Chromatography, High Pressure Liquid↗

PubMed2001

Voltametric determination of vancomycin in dosage forms through treatment with nitrous acid.

Two methods are described for the determination of vancomycin (vancomycin hydrochloride, CAS 1404-93-9) in its dosage forms. The two methods involve a prior treatment with nitrous acid then measuring the formed nitroso derivative, either spectrophotometrically or polarographically. In the spectrophotometric method, the absorbance-concentration plot is rectilinear over the range of 4-32 micrograms/ml with minimum detectability of 2.7 micrograms/ml (1.8 x 10(-6) mol/l). The apparent molar absorptivity is 4.084 x 10(-4)l.mol-1.cm-1 and A (1%, 1 cm) is 275. The reaction product was also found to be polarographically reducible at the Dropping Mercury Electrode (DME) with E1/2 of-0.9 V vs. Ag/AgCl electrode and a diffusion current constant (Id) of 0.85 +/- 0.02. The cathodic current produced was found to be diffusion controlled with some adsorption contribution. The calibration plot was linear over the range of 0.015-0.06 mmol l-1 for direct current (DCt) mode and from 0.005-0.05 mmol l-1 for differential pulse polarography (DPP) mode with minimum detectability of 2.4 x 10(-7) mol l-1 using the latter technique. The results obtained were statistically compared with those given with the official B.P. method and were in good agreement.

Anti-Bacterial Agents↗

PubMed1984

[Relation between pharmacokinetics of an antibiotic in ocular fluids and the method of administration and dosage form of gentamycin].

The experiments on rabbits with intraocular infection provided determination of the optimal route and regimen of gentamicin administration in various dosage forms. Gentamicin sulfate made in the USSR was used. It was shown that during instillations of 0.3 per cent eye drops, gentamicin did not penetrate into the intraocular fluid. The ophthalmic drug films (ODF) containing 0.5 mg gentamicin per film provided better penetration of the antibiotic into the eye cavity in the concentrations in the ocular fluid active only against the most gentamicin sensitive microbial strains. Therefore, the use of the ODF containing gentamicin may be recommended for the treatment of intraocular infections caused by gentamicin sensitive organisms. When the antibiotic was administered subconjunctively in a dose of 20 mg, its therapeutic concentrations were mainly detectable in the anterior chamber fluid. Therefore, the use of this administration route was first of all rational in intraocular infections of the anterior part of the eye. The antibiotic should be used in such cases at least twice a day. The therapeutic concentrations of gentamicin active against the majority of the microbial strains were attained in the vitreous body only on intravitreal administration. The high therapeutic levels of gentamicin in the vitreous body after its injection in a dose of 0.4 mg were recorded for at least 4 days. Therefore, for the treatment of endophthalmitis the intravitreal route of gentamicin administration is of the greatest practical importance.

Animals↗