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At least 523 records · Page 29Linked to original sources
PubMed2004

Polymer blends used for the aqueous coating of solid dosage forms: importance of the type of plasticizer.

The aim of this study was to investigate the importance of the type of plasticizer in polymer blends used for the coating of solid dosage forms, comparing a lipophilic and a hydrophilic plasticizer (dibutyl sebacate (DBS) and triethyl citrate (TEC)). In vitro drug release from propranolol hydrochloride (propranolol HCl)-loaded pellets coated with blends of ethyl cellulose (EC) and Eudragit L (100:0, 75:25, 50:50, 25:75 and 0:100 w/w) was investigated at low as well as at high pH. To better understand the underlying mass transport mechanisms, the physicochemical properties of the film coatings (e.g. mechanical resistance, water uptake and dry weight loss behavior) were determined. Interestingly, drug release strongly depended on the type of plasticizer. Importantly, not only the slope but also the shape of the release curves was affected, indicating that the chemical nature of the plasticizer plays a major role for the underlying drug release mechanisms. Diffusion through the intact polymer coatings and/or through water-filled cracks was found to be dominating for the control of drug release. The relative importance of these pathways strongly depended on the polymer blend ratio and type of plasticizer. In contrast to DBS, TEC rapidly leached out of the coatings, resulting in decreasing mechanical resistances of the films and, thus, facilitated crack formation. In addition, the hydrophilicity of the plasticizer significantly affected the water uptake behavior of the film coatings and, hence, changes in the coatings' toughness and drug permeability. Also the relative affinity of the plasticizer to the different polymers was found to be of significance. In contrast to TEC, DBS has a higher affinity to EC than to Eudragit L, resulting in potential redistributions of this plasticizer within the polymeric systems and changes in the release profiles during storage. Importantly, these effects could be avoided with appropriate curing conditions and preparation techniques for the coating dispersions.

Delayed-Action Preparations↗
PubMed1997

Determination of glafenine in dosage forms and serum by thin layer densitometry and high performance liquid chromatography.

New thin layer densitometry and high performance liquid chromatography (HPLC) methods are described for quantitative determination of glafenine in dosage forms in the presence of its photo-degradation products and in serum in the presence of its metabolites. Mobile phases consisting of toluene-isopropyl alcohol-dimethylformamide-water (18:3:1:0.5) and methanol-water-phosphoric acid (80:120:0.5) are found to be efficient for reasonable separation and adequate resolution of glafenine from associated substances by thin layer chromatography (TLC) and HPLC techniques, respectively. The methods are used for the study of glafenine purity, stability, bioavailability, bioequivalence and tablet dissolution rate. The results obtained by TLC and HPLC techniques are in good agreement and offer the advantages of reproducibility and accuracy.

Analgesics, Non-Narcotic↗
PubMed1985

Some properties of the USP content-uniformity test as related to control charts and validation of solid dosage forms.

The statistical properties of the USP content-uniformity test have been investigated in detail in other reports. This note shows that control charts for the mean potency of a solid dosage form which are constructed using typical individual content-uniformity assays in conjunction with composite assay(s), show tight limits when the product has a high probability of passing the content-uniformity test. From a practical point of view, this is a strong argument in favor of the test and recommends the test as a quality control tool.

Pharmacopoeias as Topic↗
PubMedDate not supplied

Assessment of antibiotic levels in lung tissue with erosion-controlled dosage forms.

The concentration-time curve of ciprofloxacin has been assessed in the blood compartment and in the lung tissue following oral administration of the drug. Immediate release and erosion-controlled dosage forms have been examined. A numerical model based on finite differences and taking into account all relevant data has been built: the kinetics of drug release in the gastrointestinal tract, drug absorption in the blood compartment and elimination, and the transient diffusion of the drug through the lung tissue. A partition coefficient for the drug at the tissue-blood interface has been considered to express the drug concentration at the tissue surface. The effect of dose frequency and erosion rate on the antibiotic versus time curves in the plasma and the lung tissue has been studied in detail.

Anti-Infective Agents↗
PubMed2000

A validated LC method for the quantitative determination of celecoxib in pharmaceutical dosage forms and purity evaluation in bulk drugs.

A new reversed-phase, isocratic LC method was developed for the quantitative determination of COX-2 inhibitor celecoxib in bulk drugs and in pharmaceutical dosages. The proposed method is also applicable for the purity evaluation of celecoxib in bulk drugs. 5-Methyl 2-Nitro phenol has been used as internal standard for the quantitative determination of celecoxib. The method has been completely validated and proven to be rugged. The limit of detection (LOD) and limit of quantitation (LOQ) for celecoxib impurities namely, 4-hydrazino benzene sulfonamide (Intermediate I) and 1-(4-methyl phenyl)-4,4.4-trifluro butan-1,3-dione (Intermediate II) were found to be 32.0 and 97 ng. respectively. The active pharmaceutical ingredient was extracted from its finished dosage form (capsule) using methanol. The percentage recoveries ranged from 90.7 to 93.8. The stability studies were performed for celecoxib solution placed on laboratory bench and in refrigerator for hundred days. The samples were found to be stable for the study period.

Capsules↗
PubMed2003

HPLC determination of aminophylline, methoxyphenamine hydrochloride, noscapine and chlorphenamine maleate in compound dosage forms with an aqueous-organic mobile phase.

A high-performance liquid chromatography procedure for the simultaneous determination of aminophylline, methoxyphenamine hydrochloride, noscapine and chlorphenamine maleate in commercially available compound capsule dosage forms has been developed and validated. The separation and quantification were achieved on an Ultrasphere C18 column using a mobile phase of dichloromethane-methanol-0.25% (v/v) diethylamine aqueous solution (20:60:20, v/v/v) at a flow rate of 1 ml min(-1) with detection of all analytes at 264 nm. The separation was achieved within 6 min for each drug mixture. The method showed good linearity for the aminophylline, noscapine, chlorphenamine maleate and methoxyphenamine hydrochloride mixture in the 125-750, 35-210, 10-60 and 62.5-375 microg ml(-1) ranges, respectively. The intra- and inter-day R.S.D.s ranged from 0.4 to 0.5%, 0.4-0.6%, 0.5-0.7% and 0.4-0.6% for aminophylline, noscapine, chlorphenamine maleate and methoxyphenamine hydrochloride, respectively. The recoveries (mean+/-S.D.) of low, middle and high concentrations were 99.9+/-0.9, 100.4+/-1.3 and 99.7+/-0.7% for aminophylline; 99.9+/-1.1, 100.4+/-0.7 and 100.1+/-0.8% for noscapine; 99.8+/-1.1, 99.7+/-1.0 and 100.7+/-0.8% for chlorphenamine maleate; and 99.8+/-0.9, 100.4+/-1.6 and 99.9+/-0.9% for methoxyphenamine hydrochloride, respectively.

Adrenergic beta-Agonists↗
PubMed1988

Gastric acid antisecretory effect of two different dosage forms of omeprazole during prolonged oral treatment in the gastric fistula dog.

Two series of experiments have been performed in gastric fistula dogs to test the antisecretory effect of two different oral dosage forms of omeprazole: 2 mumol x kg-1 x day-1 as a methylcellulose suspension for 8 weeks and 0.5 mumol x kg-1 x day-1 in enteric-coated granules (ECG) for 3 weeks. There was an increasing inhibitory effect during the first days of repeated administration of omeprazole, which is in accordance with its long duration of action. The steady-state inhibitory level was reached after five doses. During the 8-week treatment with the omeprazole suspension (2 mumol x kg-1) the mean maximal inhibitory level (3 h after dose) was 82%, and the mean minimal inhibitory level (24 h after dose) was 35%. With omeprazole in ECG (0.5 mumol x kg-1) the steady-state maximal inhibition (4th h) was 60%, whereas 40% inhibition remained after 24 h. Thus, a more even inhibitory level over day and night seems to be obtained with the ECG formulation than with the suspension. Basal and food-stimulated plasma gastrin levels were not significantly affected by the treatment with 0.5 mumol x kg-1, whereas food-stimulated gastrin levels were slightly increased during treatment with 2 mumol x kg-1. Control levels of acid secretion were reached within 4 days of stopping treatment. In the present studies, in which the inhibition of acid secretion varied over 24 h between approximately 80% and 35% (maximum and minimum), no rebound effects could be detected as measured up to 1 month after cessation of treatment.

Animals↗
PubMed1998

Comparison of the ocular distribution of a model oligonucleotide after topical instillation in rabbits of conventional and new dosage forms.

The distribution of a model 16-mer oligothymidylate (pdT16) in several ocular tissues (cornea, conjunctiva, sclera, iris, lens, aqueous and vitreous humors) was determined after instillation in the eye of various dosage forms in a rabbit model. Radiolabelled pdT16 was applied as a simple solution, a 27% poloxamer 407 gel, a suspension of liposomes or liposomes dispersed within a 27% poloxamer 407 gel. pdT16 concentrations were measured in the tissues and fluids by radioactivity counting at time intervals of 10 min, 2 h and 24 h. When the pdT 16 solution was used, the highest concentrations were observed in the conjunctiva and the cornea, while a substantial amount of drug was also present in the sclera. Low concentrations were measured in the iris. Using the same treatment protocol, the two liposomal formulations (liposomes suspension or liposomes dispersed within the poloxamer gel) delivered low amounts of pdT16 to all ocular tissues, and particularly to the conjunctiva and the cornea. The poloxamer gel provided higher tissue concentrations of pdT16 than liposomes but lower than those observed with the solution except 10 min after administration in the iris where the amounts of pdT16 were higher when administered under the gel form. These findings indicate that liposomal forms may not be considered useful delivery systems for topical administration of oligonucleotides in superficial ocular diseases.

Absorption↗
PubMed2002

Development of theophylline sustained release dosage form based on Kollidon SR.

Sustained release theophylline matrix tablets constituting Kollidon SR (Polyvinyl acetate and povidone based matrix retarding polymer) were developed in this study in an attempt to design a dosage form that manifests desirable release profile and thorough adherence to official monographs. Four matrix tablet formulations were prepared by dry blending and direct compression of Kollidon SR and HPMC-15cps (hydroxypropylmethylcellulose) in varying proportion with fixed percentage of theophylline. Tablets containing only Kollidon SR with the active ingredient demonstrated a rapid rate of drug release with an initial burst effect. Incorporation of HPMC-15cps in the matrix tablet prolonged the release of drug with subsequent minimization of burst effect as confirmed by mean dissolution time, T50 and Higuchi release rate data. Among the batches containing HPMC-15 cps, a direct relationship was obtained between release rate and the percentage of HPMC used. A suitable controlled release profile was obtained with the matrix tablets containing 20% Kollidon SR and 30% HPMC-15cps. The formulation showed close resemblance to commercial products and compliance with USP specification. The results were explored and explained by the difference of physico-chemical property and hydration characteristics of the polymers. In addition to this result, the exponential model was applied to characterize the drug release behaviour from polymeric systems. It was found that, Fickian release is predominant in tablets containing Kollidon SR alone and non-Fickian mechanism plays an important role in the release of drug from HPMC containing tablets with a trend towards zero-order or case II release. In vitro release profile of two commercial brands were also undertaken for comparison and modulation of the experimental batches.

Journal Article↗
PubMed1994

Analysis of Trimethoprim--sulfonamide drug combinations in dosage forms by UV spectroscopy and liquid chromatography (HPLC).

Derivative and difference spectrophotometric methods are described for the direct simultaneous analysis of combinations of Trimethoprim with sulfonamide drugs (sulfadiazine, sulfamethoxazole, sulfamethoxypyridazine) in commercial dosage forms. The more advantageous approach (derivative and difference mode) is suggested for each binary mixture. The assay results are compared with those obtained by a new chromatographic (HPLC) method, involving a C-18 column and a mobile phase (pH 6.5) containing 1.8 diaminooctane as amine modifier and sodium heptansulfonate as ion pairing agent.

Capsules↗
PubMed1998

Piroxicam fast-dissolving dosage form vs diclofenac sodium in the treatment of acute renal colic: a double-blind controlled trial.

OBJECTIVE: To assess the possible therapeutic effect of 40 mg sublingual piroxicam (fast-dissolving dosage form, FDDF) compared with intramuscular 75 mg diclofenac, as a reference drug, on acute renal colic in a randomized, double-blind controlled clinical trial. PATIENTS AND METHODS: Eighty patients were assigned to one of two treatment groups; one received an intramuscular injection with 0.2 mL distilled water and two sublingual tablets of 20 mg piroxicam FDDF, and the other received an intramuscular injection with 75 mg diclofenac sodium and two sublingual tablets of placebo. Pain intensity was evaluated by the patient using a visual analogue scale and by the observers. Vital signs at baseline and 30 min after the administration of the study drugs were also recorded. RESULTS: The overall efficacy of the treatment was 81%; nine patients in the piroxicam and six in the diclofenac group (no significant difference) required rescue treatment. Compared with baseline levels, the pain relief was significant (P < 0.001) at 30 min in both groups. Twenty-two patients in the piroxicam and 25 in the diclofenac group attained complete pain relief at 30 min, as evaluated by the observer (no significant difference). Both treatments were similarly effective in decreasing vital signs, mainly systolic blood pressure, heart and respiratory rates. However, when the percentage change was compared between the groups, piroxicam significantly decreased the respiratory rate (P < 0.03). CONCLUSION: Piroxicam FDDF is as effective as parenteral diclofenac in emergency renal colic treatment. Furthermore, its ease of self-administration increases patient compliance and potential use in general practice.

Acute Disease↗
PubMed1983

Pharmaceutical approach to subcutaneous dosage forms of insulin.

The present studies were undertaken to describe the dynamic nature of the degradation and absorption of insulin in the subcutaneous injection site and to develop agents which would stabilize this dosage form. [125I]Insulin with 0.2-U/kg of unlabeled insulin in 10 microliters of aqueous solution was injected subcutaneously in rats under the depilated skin of the back. At various times, radioactive skin tissue was extracted and assayed for insulin and/or its metabolites by gel filtration. Using these data, absorption and degradation rate constants of these substances were estimated according to a one-compartment model. Absorption rate constants of insulin and its metabolite of low molecular weight (monoiodotyrosine) were 0.021 min-1 and 0.107 min-1, respectively, while the degradation rate constant for insulin to monoiodotyrosine was 0.013 min-1. Thus, the bioavailability of insulin injected subcutaneously was lower than expected, suggesting the necessity of stabilizing methods. The protection of insulin from degradation at the site of injection was examined by the addition of various peptides. It was found that benzyloxycarbonyl-Gly-Pro-Leu-Gly was a good stabilizing agent, and remarkably inhibited insulin degradation. This inhibition was confirmed by the increase of immunoreactive insulin level and the decrease of the blood glucose level. We postulated that this peptide protects the injected insulin from degradation by inhibiting the peptidase present in subcutaneous tissue.

Animals↗
PubMed1997

Analysis of ACE inhibitors in pharmaceutical dosage forms by derivative UV spectroscopy and liquid chromatography (HPLC).

Derivative UV spectroscopy and high performance liquid chromatography (HPLC) were applied to the determination of angiotensin-converting enzyme (ACE) inhibitors in their pharmaceutical dosage forms. For spectrophotometric determinations, the more appropriate derivative order was selected for each drug: ramipril (third-order), benazepril (second-order), enalapril maleate (second-order), lisinopril (first- and second-order) and quinapril (first-order). Reverse phase HPLC procedures (ODS column) were developed able to provide a single, symmetric peak for each drug; mixtures A-B, where A is 20 mM sodium heptansulphonate (pH 2.5) and B is acetonitrile-THF (95:5 v/v), proved to be suitable mobile phases to obtain selective separations of the cited ACE inhibitors. At ambient temperature, a low pH value (2.5) was found to be critical to avoid peak splitting and band broadening.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1987

Influence of vehicle on antimicrobial efficiency of topical dosage forms of chloramphenicol.

Antimicrobial efficiency of chloramphenicol incorporated into ambiphilic emulsion bases was investigated, and it was shown that the efficiency was several times greater than the efficiency of a comercially available lipophilic dosage form. The efficiency was especially pronounced when the samples with a higher aqueous-phase content and of a lower viscosity were used. All ambiphilic preparations were stable when stored at 4 degrees C for 6 months, and when storage time was prolonged up to 1 year the most stable formulations were those which were prepared with a mixture of Tagat S and Tegin M.

Bacteria↗
PubMed2005

Determination of inorganic nitrate impurity from nicorandil and its tablet dosage form by simple reversed phase liquid chromatographic method.

A simple, fast, precise, specific and economical reverse phase liquid chromatographic method was developed for determination of nitrate (NIT) impurity from nicorandil (NIC) and its tablet dosage form. NIT is process impurity as well as a degradation product of NIC. This article is based on application of amino propyl silane (APS) column for determination of NIT in presence of NIC and various excipients using potassium nitrate as a standard. The developed method was validated for its intended use by evaluating various important parameters like linearity, accuracy, recovery and specificity. The developed method was applied to evaluate the compatibility study of NIC with various excipients by monitoring the NIT content.

Chromatography, Liquid↗
PubMed2005

Modified conventional hard gelatin capsules as fast disintegrating dosage form in the oral cavity.

Fast disintegrating capsules for administration in the oral cavity were prepared either by perforation or by vacuum-drying of conventional hard capsules. When compared to other fast disintegrating dosage forms (e.g. lyophilized sponges or tablets), these capsules have various advantages, in particular, a high drug loading capacity and no compression steps. The disintegration time of conventional hard gelatin capsules (HGC) was reduced from 91 to 39 s by introducing 6-10 small holes (diameter =25-50 microm) into the capsule shell. Vacuum-drying of conventional hard gelatin capsules resulted in brittle capsules, which broke rapidly in the oral cavity. The brittleness of the hard gelatin capsules correlated well with their moisture content. The critical moisture value for sufficient brittleness of hard gelatin capsules was <4% w/w. In contrast, HPMC capsules remained flexible, even at low moisture content. The moisture uptake of various capsule fillers was in the order of Avicel PH101 > lactose > Avicel PH112 > or = mannitol. Hard gelatin capsules filled with mannitol and packaged in bottles with silica gel kept their desired brittleness during 6 months storage at various relative humidities.

Administration, Oral↗
PubMed2003

Stability indicating HPTLC determination of linezolid as bulk drug and in pharmaceutical dosage form.

A simple, selective, precise, and stability-indicating high-performance thin layer chromatographic method of analysis of Linezolid both as a bulk drug and in formulations was developed and validated in pharmaceutical dosage form. The method employed TLC aluminium plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of toluene-acetone (5:5, v/v). This system was found to give compact spots for Linezolid (Rf value of 0.29 +/- 0.01). Linezolid was subjected to acidic, alkali hydrolysis, oxidation, and photodegradation. The degraded products also were well separated from the pure drug. Densitometric analysis of Linezolid was conducted in the absorbance mode at 254 nm. The linear regression data for the calibration plots showed good linear relationship with r2 = 0.997 +/- 0.001 in the concentration range of 300-800 ng/spot. The mean value of correlation coefficient, slope, and intercept were 0.998 +/- 0.003, 0.15 +/- 0.009, and 19.52 +/- 1.66 respectively. The method was validated for precision, accuracy, ruggedness, and recovery. The limits of detection and quantification were 20 ng/spot and 50 ng/spot, respectively. The drug undergoes degradation under acidic and basic conditions, oxidation and photo degradation. All the peaks of degraded product were resolved from the standard drug with significantly different Rf values. This indicates that the drug is susceptible to acid-base hydrolysis, oxidation, and photo degradation. Statistical analysis proves that the method is reproducible and selective for the estimation of the said drug. Because the method could effectively separate the drug from its degradation products, it can be used as a stability indicating one.

Acetamides↗
PubMed1993

Conductometric determination of some pharmaceutically important thiol compounds in dosage forms.

A direct semimicro conductometric method is described for the determination of five pharmaceutically-important thiol compounds, namely: N-acetylcysteine, captopril, D-penicillamine, 6-mercaptopurine and thioguanine, in bulk and in dosage forms. The method involves the use of lead nitrate as a titrant in aqueous medium with conductometric detection of the end point. The proposed method was successfully applied to the determination of the studied compounds and the results obtained were found to agree with those given using the official methods. The proposed method is simple, accurate and precise.

Acetylcysteine↗