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At least 973 records · Page 54Linked to original sources
PubMedDate not supplied

Dissolution assay of theophylline, diprophylline and proxyphylline from a sustained release dosage form by high performance thin layer chromatography.

The content and dissolution rate of theophylline, diprophylline and proxyphylline from a sustained release formulation were determined by UV in situ densitometry. After separation the chromatographic zones corresponding to the spots of theophylline, diprophylline and proxyphylline on the high performance thin layer chromatographic plates were scanned in reflectance/absorbance mode at 275 nm. Quantification was performed with a second degree polynomial function over the range 40-200 ng for theophylline and 60-300 ng for diprophylline and proxyphylline. Percentages of dissolved theophylline, diprophylline and proxyphylline were monitored over 1, 3 and 6 h. The method was found to be simple, accurate, reliable, time-saving (up to 18 samples can be determined simultaneously) and low-cost.

Aminophylline↗
PubMedDate not supplied

Determination of acetazolamide in dosage forms by high performance liquid chromatography.

A high performance liquid chromatographic assay for the quantitation of acetazolamide in both tablet and injection form is described. Acetazolamide is extracted with 0.005 M NaOH solution containing 0.3 mg/mL sulphadiazine (internal standard). A commercially available mu-Bondapak C18 cartridge column was used for the separation together with a mobile phase made of acetonitrile, methanol and sodium acetate buffer mixture (10:2:88) (pH 4) at a flow-rate of 4 mL/min. Retention times of about 2.50 and 3.36 min were obtained for the drug and the internal standard, respectively.

Acetazolamide↗
PubMed1976

Therapeutic efficacy of a new anhydrous theophylline dosage form.

A clinical study was performed on 41 asthmatic patients. After complete physical and spirometric examinations, they received capsules containing 200 mg anhydrous theophylline per capsule t.i.d. for three weeks. All other antiasthmatic medications were omitted during this study. The results showed that these capsules (Elixophyllin Capsules) produced statistically significant improvement in wheezing, dyspnea, global clinical assessment, vital capacity, and forced expiratory volume at 1 second. Side effects, which were generally mild and transient, were those usually reported for theophylline and were observed in 11 of the 41 patients. One patient dropped out of the study because of extreme nausea. It was concluded that theophylline as a single entity can provide significant improvement in asthmatic patients at a total daily dose of 600 mg.

Adolescent↗
PubMedDate not supplied

Steady-state lithium blood level fluctuations in man following administration of a lithium carbonate conventional and controlled-release dosage form.

A controlled-release lithium carbonate tablet was compared to an immediate release lithium carbonate capsule in normal volunteers. These crossover studies at steady state showed that the tablet produced a smoother serum curve than the capsule with no loss of total bioavailability. Quantitatively, the capsule produced about 1.4 times more fluctuation in serum lithium values than the tablet.

Adult↗
PubMed1988

Bioavailability of potassium from three dosage forms: suspension, capsule, and solution.

A crossover study was performed in 28, healthy, male volunteers to determine the bioavailability of potassium from a suspension containing microencapsulated potassium chloride compared with that from a marketed microencapsulated potassium chloride capsule and a marketed potassium chloride solution. The 20-day study consisted of four, five-day periods. In three of the periods, a single, 40-mEq dose of one of the potassium formulations was administered; no drug treatment was given in the remaining period so that the amount of potassium contributed by dietary sources could be determined. Meals were served that provided controlled amounts of potassium and sodium. Bioavailability was represented by cumulative amount of K+ excreted in urine 24 and 48 hours after drug administration. The rate of absorption was calculated from excretion rates during each of the intervals of urine collection on Days 4. The pattern of excretion exhibited by the solution indicated rapid absorption and elimination. The potassium from the suspension and the capsules was excreted more slowly and over a longer period, indicating that the potassium content from these formulations was not being dumped. No statistically significant differences between the suspension and the capsules were found. The extent of absorption of K+ was similar from all three products, and the potassium from the suspension was found to be fully bioavailable when compared with the liquid and the capsule.

Adult↗
PubMed2003

Once-a-day controlled-release dosage form of divalproex sodium II: development of a predictive in vitro drug release method.

During formulation design of a once-daily controlled release matrix system of divalproex sodium, the in vitro dissolution test (USP II, 100 rpm, pH 6.8 buffer) was found to result in release rates that were slower than in vivo absorption. The test method also did not sufficiently discriminate formulations with different in vivo absorption rates. To develop an in vitro method that is directly correlated with in vivo absorption, statistically designed studies were carried out to investigate the effects of various in vitro testing variables on drug release using USP dissolution apparatuses. The variables studied included agitation intensity, apparatus, pH, surfactant and ionic strength of the dissolution medium. Experimental data were analyzed using ANOVA. In vitro/in vivo correlation was tested based on the hypothesis that the same linear regression equation holds for three formulations with different release rates. A mixed effects model was used in which the dependence among observations from the same subject was taken into account. Factorial studies indicated that higher pH, addition of sodium lauryl sulphate (SLS) to the dissolution medium, and higher agitation intensity increased the release rate from the matrix tablet. Use of SLS not only lead to increased release rates that are more comparable to in vivo absorption rates, but also improved differentiation among formulations with varying release rates. Furthermore, drug release was also affected by interactions among the variables studied. Statistical analysis indicated that a combination of higher SLS concentration and lower pH provided enhanced differentiation between release profiles of the fast and slow releasing formulations. Based on the above findings, a new set of testing conditions was identified and demonstrated to be predictive of in vivo drug absorption for various controlled release formulations of divalproex sodium. The new method uses USP Apparatus II operating at 100 rpm in 500 mL of 0.1 N HCl for 45 min followed by 900 mL of 0.05 M phosphate buffer containing 75 mM SLS, pH 5.5, 37 +/- 0.5 degrees C. In conclusion, adjusting dissolution testing conditions to match the behavior of the formulations in vitro with that in vivo is a useful approach in identifying a predictive method in development of in vitro-in vivo correlation.

Anticonvulsants↗
PubMed2005

Biowaiver monographs for immediate release solid oral dosage forms based on biopharmaceutics classification system (BCS) literature data: chloroquine phosphate, chloroquine sulfate, and chloroquine hydrochloride.

Literature data on the properties of chloroquine phosphate, chloroquine sulfate, and chloroquine hydrochloride related to the Biopharmaceutics Classification System (BCS) are reviewed. The available information indicates that these chloroquine salts can be classified as highly soluble and highly permeable, i.e., BCS class I. The qualitative composition of immediate release (IR) tablets containing these Active Pharmaceutical Ingredients (APIs) with a Marketing Authorization (MA) in Belgium (BE), Germany (DE), Finland (FI), and The Netherlands (NL) is provided. In view of these MA's and the critical therapeutic indication of chloroquine, it is assumed that the registration authorities had evidence that these formulations are bioequivalent to the innovator. It is concluded that IR tablets formulated with these excipients are candidates for a biowaiver.

Antimalarials↗