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PubMed2004

Role of blooming in determining the storage stability of lipid-based dosage forms.

Gelucire 50/13 alone and solid dispersions in this material containing two model drugs (10% w/w caffeine and paracetamol) have been studied with a view to establishing the mechanism underpinning changes in drug-release characteristics as a function of storage time and temperature. The lipid systems were fabricated into tablets and stored for up to 180 days at temperatures of 20 and 37 degrees C. The dispersions were studied using differential scanning calorimetry (DSC), scanning electron microscopy, and dissolution testing. DSC studies indicated that the Gelucire 50/13 exists in two principal melting forms (melting points 38 and 43 degrees C) that undergo transformation to the higher melting form on storage at 37 degrees C. Scanning electron microscopy studies indicated that the systems exhibit "blooming," with crystal formation on the surface being apparent on storage at both temperatures. The dissolution rate increased on storage, with the effect being particularly marked at higher storage temperatures and for the paracetamol systems. However, whereas these changes corresponded well to those seen for the morphology, the correlation between the changes in dissolution and those of the DSC profiles was poor. The study has suggested a novel explanation for the storage instability of Gelucire 50/13 whereby the change in dissolution is associated not with molecular rearrangement as such but with the gross distribution of the constituent components, this in turn altering the physical integrity of the lipid bases.

Dosage Forms↗
PubMedDate not supplied

UV spectrophotometry and nonaqueous determination of terbinafine hydrochloride in dosage forms.

An ultraviolet spectrophotometric and a nonaqueous volumetric method for determining terbinafine hydrochloride (TH) in pharmaceutical formulations are presented. The UV spectrophotometric procedure was developed for assay of TH in raw materials, tablets, and creams. The method was tested for linearity (0.8-2.8 micrograms/mL, r = 0.9997), recovery (102.00% for creams and 99.90% for tablets) and precision (101.3%, CV = 0.96%, n = 9, for creams; 100.25%, CV = 1.08%, n = 9, for tablets). The volumetric method involves titration of TH with 0.05M perchloric acid with crystal violet as indicator. This method was used for quantitative determination of TH in raw materials and tablets. Mean recovery and precision were, respectively, 100.41 and 101.18% (CV = 1.64%, n = 9) for TH tablets. There were no significant differences between the proposed methods and a previously described high-performance liquid chromatographic method. The UV spectrophotometric and titrimetric methods are potentially useful for a routine laboratory because of their simplicity, rapidity, and accuracy.

Antifungal Agents↗
PubMedDate not supplied

[Problems posed by the adjusting of a dosage form of a drug for children].

The safe use of drugs for pediatric patients is based upon good conditions of administration, in order to ensure accuracy and reproducibility of the dose received. But dosage adjustment often needs also a transformation of the galenic form, and that involves many risks or error. Some solutions are proposed in order to standardize the methods of drug adjustment for pediatric use.

Child↗
PubMed2004

Solid state NMR and DSC methods for quantifying the amorphous content in solid dosage forms: an application to ball-milling of trehalose.

The purpose of this study was to determine quantitatively the amorphous fraction in crystalline-amorphous powder mixtures of trehalose, in order to assess the ability of the (13)C NMR technique for quantitative amorphous characterization. The NMR method is described in detail and its accuracy is compared to that of the DSC technique. Amorphous trehalose was prepared by mechanical milling. Samples with different amorphous fractions were prepared by physical mixing of purely amorphous and purely crystalline powders. The results reveal a close correlation between the imposed compositions of the physical mixtures and those determined by NMR and DSC, indicating that both are useful and accurate methods for compositional characterization of powders. The NMR method is then used to determine the evolution of the amorphous fraction in a trehalose powder, during a milling procedure which ultimately leads to a fully amorphous state.

Calorimetry, Differential Scanning↗
PubMed1998

Pitfalls of artificial neural networks (ANN) modelling technique for data sets containing outlier measurements using a study on mixture properties of a direct compressed dosage form.

An application of the Artificial Neural Networks (ANN) methodology was investigated using experimental data from a mixture properties study and compared to classical modelling technique (i.e. Response Surface Methodology, RSM) both graphically and numerically. The aim of this investigation was to quantitatively describe the achieved degree of data fitting and robustness of the developed models. For comparing the goodness of fit, the R2 coefficient was used, whereas for the robustness of the models an outlier measurement was integrated in the data set. Comparable results were achieved for both ANN- and RSM methodologies for data fitting. The robustness of the models towards outliers was clearly better for the RSM methodology. All determined mixture properties were mainly influenced by the concentration of silica aerogel, whereas the other factors showed very much lower effects. For that reason the physical properties of this excipient (e.g. its specific surface area) are of importance for the behaviour of the mixtures.

Chemistry, Pharmaceutical↗
PubMed2003

Determination of binary mixtures of analgesic and spasmolytic drugs in pure and dosage forms by derivative spectrophotometry.

Binary mixtures of dipyrone and pitophenone hydrochloride are assayed by zero-crossing second- and third-derivative spectrophotometry and by ratio-spectra first- and second-derivative spectrophotometry. In the first method, calibration plots are linear at 266.5 and 302.5 nm (dipyrone, second derivative), and 257 and 286 nm (pitophenone second derivative) and 242 and 278.3 nm (dipyrone third derivative), and 228.5 and 300 nm (pitophenone, third-derivative). By the second method, lines of regression are linear at 235 and 262 nm (dipyrone, first derivative), and 229.5 and 288.5 nm (pitophenone, first-derivative), and 249.7 and 268 nm (dipyrone, second derivative), and 280.5 and 300 nm (pitophenone, second-derivative). In all methods calibration curves follow the Beer's law up to 40 microg/ml of each drug. LOD and LOQ values were calculated. The developed derivative spectrophotometric methods were applied to laboratory mixtures and to vials for these drugs. The procedures are simple, rapid, and did not require any preliminary separation or treatment of the samples.

Analgesics↗
PubMed2002

Spectrophotometric determination of enoxacin as ion-pairs with bromophenol blue and bromocresol purple in bulk and pharmaceutical dosage form.

Three simple, accurate and sensitive spectrophotometric methods were developed for determination of enoxacin. The methods based on extraction of this drug into chloroform as ion pairs with sulphonphthalein dyes as bromophenol blue and bromocresol purple. The optimum conditions of the reactions were studied and optimized. The absorbance of yellow products was measured at 412 nm for enoxacin-bromophenol blue and 410 nm for enoxacin-bromocresol purple. Linearity ranges were found to be 2.0-20.0 microg ml(-1) for enoxacin-bromophenol blue and 0.77-17.62 microg ml(-1) for enoxacin-bromocresol purple. The detection limits were found to be 0.084 microg ml(-1) and 0.193 microg ml(-1) for enoxacin-bromophenol blue and enoxacin-bromocresol purple, respectively. The composition of the ion pairs was found 1:1 by Job's method. The developed methods were applied successfully for the determination of this drug in pharmaceutical preparation. The data obtained by developed methods were compared with the spectrophotometric method in literature. No differences were found statistically.

Bromcresol Purple↗
PubMed1977

Column chromatographic analysis of barbiturates in their dosage forms. IV. Combinations with parabens.

The nature of the alkaline hydrolysis of some barbiturates in combinations with parabens (p-hydroxybenzoates) was studied with controlled variables, including temperature, viscosity, and concentrations of sodium hydroxide, barbiturate, and parabens. The kinetic studies showed that parabens could be completely hydrolyzed in strong base at 40 degrees C in 1 hr, while the barbiturate remained intact and was readily isolated by partition chromatography, Based on the theoretical results, a partition chromatographic procedure for butabarbital with parabens was devised. Standard recoveries averaged 100.7% with a standard deviation of 0.89. Kinetic data indicate that the hydrolysis of parabens could also be applied to analyze combinations with amo-, seco-, and pentobarbitals. Phenobarbital and parabens are readily separated by partition chromatographic methods without prior hydrolysis of the parabens. The low extraction constant for phenobarbital allowed its retention on a column against relatively strong solvents while the intact parabens are eluted. A slightly modified method was applied to the separation of phenobarbital from parabens. Standard recoveries average 99.9% with a standard deviation of 0.69.

Barbiturates↗
PubMed1999

Simultaneous determination of some multicomponent dosage forms by quantitative thin layer chromatography densitometric method.

In this study, simultaneous determination of naproxen with diflunisal (mixture I), paracetamol with chlorzoxazone (mixture II) and chlorphenoxamine hydrochloride with 8-chlorotheophylline and caffeine (mixture III) in multicomponent mixtures was conducted by a thin layer chromatography densitometric method. The mobile phase ethyl acetate: methanol: ammonia 25% (85:15:5 v/v) was used for the separation of the components of mixtures (I) and (II) with Rf values of 0.16 for naproxen, 0.4 for diflunisal, 0.77 for paracetamol and 0.32 for chlorzoxazone. Efficient separation of the components of mixture (III) was attained using ethyl acetate as mobile phase with Rf values of 0.12, 0.62 and 0.42 for chlorphenoxamine hydrochloride, 8-chlorotheophylline and caffeine, respectively. Linearity ranges, mean recoveries and relative standard deviations in calibration graphs of the proposed method were calculated. The method has been successfully applied to pharmaceutical formulations, sugar-coated tablets, capsules and suppositories. The results obtained were statistically compared with those obtained by applying the reported alternate methods.

Acetaminophen↗
PubMed1995

Release of lidocaine from polymer film dosage forms.

We investigated the in vitro drug release from mixed polymer films using lidocaine (LC), which is poorly water-soluble. The mixed polymer films consisted of various ratios of hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose phthalate (HPMCP). The effects of the presence glycyrrhizic acid (GL) or polyethylene glycol (PEG) in the films upon LC release were also studied. LC crystallinity decreased in the polymer film and this decrease was remarkable in the presence of GL, resulting in an amorphous state. During the initial stage, drug release was regarded as a zero-order dissolution. The apparent release rate constant, ka, varied with the ratios of the two polymers and the amount of additives as well as with the pH of the test solution. The results indicated that GL enhanced the dissolution rate of LC from mixed polymer films, which may be due to the formation of an amorphous state. On the other hand, since PEG is a surfactant, the enhanced wettability of the polymer by the buffered solutions may have caused the increased dissolution rate.

Calorimetry, Differential Scanning↗
PubMed2005

Spectrofluorometric determination of montelukast in dosage forms and spiked human plasma.

The native fluorescence of montelukast has been studied under different experimental conditions. The highest fluorescence intensity was obtained in methanol at 390 nm using 340 nm for excitation. Surfactants and sensitizers had either a negative or a slightly positive effect on its fluorescence intensity. The fluorescence intensity-concentration plot was rectilinear over the range 0.125 to 5 microg/ml with a lower detection limit of 0.02 microg/ml (3.4 x 10(-8) M). Interference likely to be introduced from co-formulated drugs (such as loratadine) or co-administered drugs (such as verapamil, carbazepam, propranolol) or other common drugs, was studied. The method was successfully applied to the determination of the drug in tablets (pediatric tablets, chewable tablets and adult tablets). The mean % recoveries were in agreement with those provided by the manufacturer. The method was further applied to the in vitro determination of montelukast in spiked human plasma, the mean % recovery (n = 5) was 100.08 +/- 1.40.

Acetates↗
PubMed2003

Understanding the physical stability of freeze dried dosage forms from the glass transition temperature of the amorphous components.

Modulated differential scanning calorimetry has been applied to understanding the long-term physical stability of freeze-dried units. It is known that these units are liable to contract on exposure to elevated temperature or humidity. The contraction occurs when the storage temperature is above the glass transition temperature of the amorphous components in the system. The effect of moisture content on the glass transition temperature of the amorphous components in the system has been studied. By combining this information with the moisture sorption isotherm it has been demonstrated that it is possible to predict the temperature and humidity conditions that will induce contraction of the unit. The magnitude of the glass transition temperature is composed of the contribution of each of the amorphous components in the system. It is proposed that it should be possible to develop a more robust system by the rational selection of excipients that increase the glass transition temperature or by modification of the processing conditions to promote crystallization of components that would otherwise depress the glass transition temperature.

Dosage Forms↗
PubMed2003

Liquid chromatographic determination of pyronaridine in human plasma and oral dosage form.

A new procedure for the determination of pyronaridine in plasma by reversed-phase high performance liquid chromatography (HPLC) with UV detection at 278 nm is described. The method involves liquid-liquid extraction of the drug with diethyl ether following basification of the deproteinized plasma with alkaline phosphate buffer. Chromatographic separation was achieved using a microbore C-18 column and a mobile phase consisting of 0.1% aqueous trifluoroacetic acid (TFA)-acetonitrile (75:25% (v/v)), pH 2.2, at a flow rate of 0.07 ml/min. Papaverine was used as internal standard. The response was linear between 50 and 1500 ng/ml. The limit of quantitation (LOQ) after plasma extraction was 50 ng/ml, the intra- and inter-day precision ranged from 2.5 to 13.8% (CV). The recovery of the drug from plasma and accuracy were >90%. Preliminary application of the method for monitoring pyronaridine in humans upon oral administration of the tablet demonstrated the principal usefulness of the assay for clinical trial studies. The method can also be used to analyze the compound in pharmaceutical formulations.

Administration, Oral↗
PubMed2003

Determination of cisapride, its oxidation product, propyl and butyl parabens in pharmaceutical dosage form by reversed-phase liquid chromatography.

A simple, rapid and reproducible high-performance liquid chromatography (HPLC) assay for cisapride, its oxidation product (OP), propyl and butyl parabens in a pharmaceutical formulation is described. Chromatography was performed at room temperature by pumping acetonitrile-20 mM phosphate buffer pH 7 (50:50, v/v) at 1.5 ml min(-1) through C8 reversed-phase column. Cisapride, OP, propyl and butyl parabens were detected at 276 nm and were eluted at 9.7, 3.1, 5.1 and 7.1 min, respectively. Calibration plots were linear (r>0.999) for all compounds from 0.5 to 200 microg ml(-1) for cisapride and OP and 0.1-200 microg ml(-1) for propyl and butyl parabens. Detection limits for cisapride, OP, propyl and butyl parabens were 40, 46, 48 and 54 ng ml(-1), respectively. Forced degradation investigations showed that cisapride does not undergo degradation under heat, acidic and basic conditions but it was susceptible to oxidation. The proposed method was successfully applied to the assay of cisapride in the presence of preservatives and OP in a commercial suspension.

Chromatography, High Pressure Liquid↗
PubMed2001

Patients' evaluation of shape, size and colour of solid dosage forms.

AIM: The aim of the study was to investigate the swallow ability and the patient preferences of tablets and capsules with different sizes, shapes, surfaces and colours. METHOD: Patients were asked to swallow tablets with different surface and size, while tablets with different shape and colour were visually assessed. They were asked to indicate their preferences. RESULTS: Gelatine capsules were found easier to swallow than tablets and coated tablets were found easier than uncoated normal tablets. The preferred colour was white both for tables and capsules, and the most disliked colours were purple tablets and brown capsules. The preferred shape was strongly arched circular for small tablets, oval for medium sized and big tablets. The difficulty to swallow tablets increased with increasing size. CONCLUSION: According to the results of this study, the ideal tablet is small and white, strongly arched circular and coated. If the amount of drug requires a bigger tablet, the preferred fomat is oblong or oval with a coating. In general capsules were preferred over tablets.

Adult↗
PubMed2000

An approach to controlled-release dosage form of propranolol hydrochloride.

It is possible to release a drug with only limited diffusion from a membrane-coated system using osmotic pumping. In this study, a propranolol osmotic pump was produced by coating the core tablets with cellulose acetate. The effects of membrane thickness, pore size, and stirring rate on the release rate of propranolol hydrochloride were studied. It was found that the thickness of cellulose acetate membrane had a profound effect on the release rate of propranolol hydrochloride from the membrane-coated tablets. The results showed that, when the membrane thickness increased, the release rate of propranolol decreased. The drug release follows a zero-order release when the delivery orifice is between 200 and 800 microns, but when the delivery orifice size is increased to 1000 microns, the release kinetic is abnormal. Fluid dynamics have an important effect on the delivery rate of propranolol from this device; the delivery rate increases as a function of the fluid flow. The drug release is higher under a turbulent condition with high rate of stirring.

Adrenergic beta-Antagonists↗
PubMed1998

In-vivo monitoring of dosage forms.

The use of imaging techniques including gamma scintigraphy to follow the behaviour of drug formulations has revolutionized our knowledge of absorption and distribution in drug delivery. The development of gamma camera techniques as physiological tools to explore organ function became routine by the mid-seventies. Several research groups started to explore the applications of technique in drug delivery. Within 5 years, the utility of the technique became obvious and scintigraphy is now widely accepted as an important investigation tool in formulation research. Gamma scintigraphy is especially useful in exploring sources of inter-subject variation, especially in examining food effects in pharmacokinetic estimations and establishing windows of absorption for oral delivery. As a tool to examine drug delivery to the lung and to the eye, scintigraphy is the method of choice. Magnetic Resonance Imaging (MRI) became more generally employed in medicine two decades after the gamma camera. The superior soft-tissue contrast and resolution compared to computed X-ray tomography rapidly established MRI in clinical investigation. Recent applications in oral drug research has allowed the pharmaceutical scientist to explore new facets of delivery and ultimately combine MRI and scintigraphy in human clinical trials.

Dosage Forms↗
PubMed2006

Development and validation of liquid chromatographic and UV derivative spectrophotometric methods for the determination of famciclovir in pharmaceutical dosage forms.

A high-performance liquid chromatographic method and a UV derivative spectrophotometric method for the determination of famciclovir, a highly active antiviral agent, in tablets were developed in the present work. The various parameters, such as linearity, precision, accuracy, specificity, robustness, limit of detection and limit of quantitation were studied according to International Conference on Harmonization guidelines. HPLC was carried out by using the reversed-phase technique on an RP-18 column with a mobile phase composed of 50 mM monobasic phosphate buffer and methanol (50 : 50; v/v), adjusted to pH 3.05 with orthophosphoric acid. The mobile phase was pumped at a flow rate of 1 ml/min and detection was made at 242 nm with UV dual absorbance detector. The first derivative UV spectrophotometric method was performed at 226.5 nm. Statistical analysis was done by Student's t-test and F-test, which showed no significant difference between the results obtained by the two methods. The proposed methods are highly sensitive, precise and accurate and therefore can be used for its Intended purpose.

2-Aminopurine↗