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At least 199 records · Page 11Linked to original sources

PubMed1987

Dissolution of theophylline from sustained-release dosage forms and correlation with saliva bioavailability parameters.

Correlation between in vitro dissolution characteristics and in vivo salivary bioavailability parameters of four commercial sustained-release and one immediate-release theophylline (TP) or aminophylline dosage forms were examined. Area under the saliva concentration-time curve up to 6 h (AUC0----6), peak saliva concentration (Cmax), and fraction absorbed in 1 h (F1), based on saliva concentration following oral administration of TP or aminophylline dosage forms to five volunteers, were closely correlated with percents dissolved in pH 6.8 buffer in 30 min, D30 (6.8), or 60 min, D60 (6.8). Dissolution study in pH 6.8 buffer seemed to be a useful tool for development, evaluation, and quality control of sustained-release dosage forms of TP, since the saliva concentration was reported to represent the blood concentration of TP indirectly.

Adult↗

PubMed1991

Redispersible dry emulsion system as novel oral dosage form of oily drugs: in vivo studies in beagle dogs.

The absorption characteristics of vitamin E acetate (VEA) formulated into a dry emulsion system after its oral administration to beagle dogs were determined and compared to those of two different dosage forms (an oily mixture of the drug with cottonseed oil and an oil (drug)-in-water emulsion). The three dosage forms were administered in a crossover fashion to six nonfasting subjects, and the drug absorption was assessed from the plasma concentration of the major metabolite (free vitamin E). VEA formulated in the dry emulsion was rapidly absorbed, which suggested that a considerable amount was released as reformed emulsion droplets in the gastrointestinal tract as well as in water in vitro. Based on the analysis of variance, no significant differences in bioavailability parameters (AUC, Cmax or Tmax) were observed among the three dosage forms.

Administration, Oral↗

PubMed2006

Isocratic RP-HPLC method for rutin determination in solid oral dosage forms.

A rapid and sensitive assay for quantitative determination of rutin in oral dosage forms based on isocratic reversed phase high performance liquid chromatography (RP-HPLC) was developed and validated. Using a C(18) reverse-phase analytical column, the following conditions were chosen as optimal: mobile phase methanol-water 1:1 (v/v), pH 2.8 (adjusted with phosphoric acid), flow rate=1 mL min(-1) and temperature T=40.0 degrees C. Linearity was observed in the concentration range 8-120 microg mL(-1) with a correlation coefficient of 0.99982 and the limit of detection (LOD)=2.6 microg mL(-1), and limit of quantification (LOQ)=8.0 microg mL(-1). Intra- and inter-day precision were within acceptable limits. Robustness test indicated that the mobile phase composition and pH influence mainly the separation. The proposed method allowed direct determination of rutin in pharmaceutical dosage forms in the presence of excipients, but is not suitable for preparations where compounds structurally/chemically related to rutin may be present.

Capsules↗

PubMed2006

Current perspectives in dissolution testing of conventional and novel dosage forms.

The purpose of this article is to review USP and non-pharmacopeial dissolution testing methods for conventional and novel pharmaceutical dosage forms and give an insight to possible alternatives in drug dissolution study design and appropriate choices for dissolution media. For each dosage form first the USP method(s) for dissolution testing are reviewed followed by alternative methods used in research and development.

Administration, Cutaneous↗

PubMed2004

The ophthalmic lyophilisate carrier system (OLCS): development of a novel dosage form, freeze-drying technique, and in vitro quality control tests.

The ophthalmic lyophilisate carrier system (OLCS) is a novel dosage form for delivery of pharmacologically active ingredients or other substances improving the structure of the tear film to the eye. A drop of lyophilisate containing the drug and bulk forming water-soluble or swelling excipients is attached to a flexible hydrophobic carrier. Placebo OLCS and OLCS containing several drugs commonly used in ophthalmology were compared to conventional eye drops containing the same ingredients. A novel lyophilization procedure for the production of this dosage form is described, which allows stricter control of the freezing and drying conditions and shortens the production cycle by at least an order of magnitude. In clinical studies it was found that OLCS are easy to administer and well tolerated if the force of adhesion between lyophilisates and carrier strips and the structural firmness of the lyophilisates themselves are well controlled. These parameters are critical for convenient administration and complete delivery of the dose of active ingredients incorporated, therefore suitable in vitro tests were developed with which their values can be determined for the purpose of process validation. A study of fluorescein OLCS in humans indicated that concentration profiles in the cornea and anterior chamber are significantly higher than after administration of equal doses of the diagnostic in conventional eye drops.

Dosage Forms↗

PubMedDate not supplied

Evaluation of online drug references for identifying over-the-counter solid oral dosage forms.

OBJECTIVE: To evaluate six drug references for their usefulness in identifying over-the-counter (OTC) solid oral dosage forms (SODFs). DESIGN: Retrospective evaluation of a convenience sample of requests for product identification. SETTING: Drug information center that accepts information requests from health care providers and law enforcement officials throughout the state in which it is located. PARTICIPANTS: Researchers. INTERVENTIONS: Using a convenience sample of 68 nonprescription drugs and 41 dietary supplements obtained from the drug information center's question and answer database, researchers sought to identify the SODFs using six drug-identification online databases. MAIN OUTCOME MEASURE: Likelihood of identifying a SODF with a given reference, reported as the percentage identified and the corresponding 95% confidence interval. RESULTS: Overall, 88.2% of nonprescription drugs could be identified using all six references. The highest percentage of nonprescription drugs (77.9%) were identified using Identidex, followed by Ident-A-Drug (67.6%), Drug Identifier (45.6%), RxList (39.7%), Lexi-Drug ID (33.8%), and Clinical Pharmacology (17.6%). Using Ident-A-Drug and RxList together led to the identification of two fewer nonprescription drugs than did Identidex at approximately 5% of the cost. Only 15 (37.5%) of the dietary supplements had an identifying imprint on the dosage form, and 7 (46.6%) of the imprinted products were identified. But overall, only 17.1% (7 of 41) of dietary supplements could be identified, as none of the products without imprints could be positively identified. CONCLUSION: Using these six online references, nonprescription drugs could be identified more frequently than could dietary supplements. The lack of imprints on many dietary supplements is an impediment to identification of these products.

Administration, Oral↗

PubMedDate not supplied

Performance characteristics of methods of analysis used for regulatory purposes. I. Drug dosage forms. E. miscellaneous methods.

Precision parameters of miscellaneous methods for the analysis of drug dosage forms approved by AOAC since 1972, and not previously reviewed in this series, were recalculated on a consistent statistical basis by using the computer program FDACHEMIST. Seventeen published collaborative studies were reviewed; the studies encompassed 19 analytes in 80 different materials (dosage forms), 102 collaborative assays, approximately 10 laboratories per study, and principally direct spectrophotometric, polarographic, and spectroscopic methods, for a total of 1451 determinations. The average repeatability relative standard deviation (within-laboratories, RSDo) for the instrumental methods was 1.5%; the reproducibility relative standard deviation (among-laboratories, including within-, RSDx) was 2.6%; the ratio RSDo/RSDx of the averages was 0.57, with an average outlier rate of 2.7% of the reported determinations. The line of best fit of RSDx for the instrumental methods plotted against the negative logarithm of the concentration increases slightly with decreasing concentration, extending from an RSDx of approximately 2.0% at 100% concentration to an RSDx of 3.4% at 0.001% (10 ppm) concentration; this represents an RSDx change of approximately 0.3% (absolute) for each 10-fold decrease in concentration, independent of analyte, matrix, and method. A method for determining precipitated allergenic protein by the micro-Kjeldahl technique appeared to be outside this general relation, showing an RSDx of about 13% at a concentration of 0.015% (150 ppm) nitrogen.

Allergens↗

PubMed1975

Bioavailability of micronized griseofulvin from corn oil-in-water emulsion, aqueous suspension, and commercial tablet dosage forms in humans.

The purposes of this investigation were to determine and to compare the oral absorption characteristics of micronized griseofulvin (500 mg) after its administration to humans in the form of a corn oil-in-water emulsion containing dispersed drug, an aqueous suspension, and two different commercial tablets (A and B). The four dosage forms were administered in a random crossover fashion to five fasting subjects, and drug absorption was assessed from urinary excretion data for the major metabolite of the antibiotic (6-desmethylgriseofulvin). The drug was most rapidly, uniformly, and completely absorbed from the corn oil-in-water emulsion. As compared to either the aqueous suspension, Tablet A, or Tablet B, three- to fourfold increases in the maximum body levels and a twofold enhancement in the bioavailability of the antibiotic were observed after administration of the emulsion dosage form. A mechanism based on the ability of the linoleic and oleic acids liberated during the digestion of corn oil to inhibit GI motility and stimulate gallbladder evacuation may explain the marked enhancing effect of emulsified corn oil on griseofulvin absorption in humans. This new lipid-in-water emulsion dosage form of micronized griseofulvin appears to offer several clinical advantages in the treatment of fungal infections.

Adult↗

PubMed1995

Evaluation of polysaccharides intended for ophthalmic use in ocular dosage forms.

Different water-soluble polysaccharides were evaluated for their intended use in ocular dosage forms. The physicochemical characteristics and the viscosity of the solutions prepared with several iso-osmotic vehicles were measured. The influence of ions present in lacrimal fluid, mucin and cyclodextrin on the rheological behaviour was examined. Scleroglucan and xanthan gum exhibit viscoelastic and mucoadhesive properties useful for ocular dosage form formulations.

Cyclodextrins↗

PubMed1983

High-performance liquid chromatographic determination of nitroglycerin in sublingual, sustained-release, and ointment dosage forms.

A rapid, precise, sensitive, and specific assay for nitroglycerin in sublingual, sustained-release, and ointment dosage forms using high-performance liquid chromatography is described. The nitroglycerin dosage forms were dissolved in methanol, filtered, and injected directly into the liquid chromatograph. A variable-wavelength UV detector operated at 220 nm and a C18 microporous silica column were employed. The mobile phase was methanol-water (40:60).

Capsules↗

PubMedDate not supplied

[Present and future choices of vaginal drug dosage forms. I. Classical forms].

The anatomy and physiology of vagina play a major role in the formulation of vaginal products. In this review, many classical dosage forms (tablets, suppositories, creams, gels, foams...), used either for local or systemic treatment are described and discussed. Formulation and essay are briefly reviewed. But emphasis is layed on the problems associated with the administration of these dosage forms, their advantages with regard to other vaginal products and the use of these products as contraceptive devices.

Administration, Intravaginal↗

PubMedDate not supplied

Stability of dapsone in two oral liquid dosage forms.

OBJECTIVE: Dapsone use in pediatric patients is increasing; however, the currently available tablet dosage form cannot be used in young children. The objective of our study was to determine the stability of dapsone in two oral suspensions stored at two temperatures. METHODS: Commercially available dapsone tablets (25 mg) were used to prepare the suspensions: the first in simple syrup and water with citric acid, the second in 1:1 Ora Sweet:Ora Plus to yield a concentration of 2.0 mg/mL. The dosage forms were stored in 10 amber plastic prescription bottles. Five were stored at 25 degrees C and five at 4 degrees C. Three samples were taken from each of five bottles at 0, 7, 14, 28, 42, 56, 70, and 91 days (n = 15). Dapsone concentrations in each sample were measured in duplicate by a validated and stability-indicating HPLC method; the pH of each sample was also determined. The drug was considered stable if the mean concentration > or =90% of the original concentration. RESULTS: The mean concentrations of dapsone were >95% of the initial concentrations for 91 days at both 4 degrees C and 25 degrees C in each suspension. There was a slight darkening of the samples stored at 25 degrees C. CONCLUSIONS: Dapsone was stable in two suspensions prepared from commercially available tablets for at least three months at 4 degrees C and 25 degrees C.

Administration, Oral↗

PubMed1994

Determination of chloroquine and its decomposition products in various brands of different dosage forms by liquid chromatography.

Various commercial preparations of chloroquine dosage forms have been examined both by thin-layer chromatography (TLC) and liquid chromatography (LC). TLC showed that all these preparations yielded more than one spot, indicating possible degradation. An LC method has been adapted for the determination of chloroquine in these drug formulations. The standard calibration curve was linear over the concentration range 1-6 micrograms ml-1. Chloroquine was assayed in various brands of different forms (ampoules, tablets and syrups). However, it was observed, for some samples, that the bands obtained were rather broad, showing shoulders or peak splitting, indicating the presence of other compounds coeluting with chloroquine. The utility of this method for the quality control of this major drug is assessed in the context of the need to carefully monitor drug purity in a tropical climate, particularly in situations where there may be doubt about the quality of the primary manufacturer.

Chloroquine↗

PubMed1977

Use of microcapsules as timed-release parenteral dosage form: application as radiopharmaceutical imaging agent.

The development of a new type of parenteral dosage form is described. A system of microencapsulation was formulated which produced microcapsules containing a water-soluble core material. The basic microencapsulation system could be altered to produce microcapsules with varied timed-release characteristics. Tracer methodology was employed as a sensitive and versatile analytical tool for the development and evaluation of the microencapsulation system. The core material was labeled by neutron activation after microcapsule formulation, which eliminated the radiation hazard and contamination problems that could occur during formulation with a labeled core material. Both in vitro and in vivo testing showed that the release patterns of labeled core material could be altered and detected. The microcapsules developed have potential as a timed-release parenteral dosage form and as an organ-imaging radiopharmaceutical.

Animals↗

PubMed2000

Leakage of enteric (Eudragit L)-coated dosage forms in simulated gastric juice in the presence of poly(ethylene glycol).

Poly(methacrylic acid) (PMAA) and related copolymers strongly interact with poly(ethylene glycol) (PEG) in acidic fluids. Due to the in vitro experiments presented in this paper, there is a clear indication for a drug-drug interaction in vivo between PEG solutions, e.g., commercially available laxatives, and dosage forms with PMAA-based enteric-coatings (Eudragit L). In these studies, enteric-coated tablets did not fulfil the pharmacopoeias' criteria of the disintegration test if PEGs were present in the simulated gastric juice. Drug substances which are known to be unstable in acidic media or which can cause gastric irritation were released from their enteric-coated dosage forms in acidic PEG media (pH 1). Various drug dosage forms, single and multiple unit systems, were tested. They show higher and faster drug release in the presence of PEG. To get insight into the mechanism of the interaction, experiments and theoretical calculations were performed which reveal that PEGs with high molecular weight show stronger interactions with PMAA coatings indicating a contribution of hydrophobic interactions to the occurring intermolecular forces. Hydrogen bonds can be build between each monomeric unit of PEG and the acidic sequences of the copolymer.

Calorimetry, Differential Scanning↗

PubMed2003

A multimechanistic drug release approach in a bead dosage form and in vitro predictions.

The objective of this study was to prepare a combination of immediate release, enteric coated, and controlled release (CR) beads and to mathematically model in vitro drug release characteristics of the combination based on the release profiles of individual beads. Uncoated beads were manufactured by using extrusion/spheronization technology. Fluid-bed bottom spraying was used for coating: Eudragit-L-30D for enteric coating and Eudragit-NE-30D for CR coating. In vitro drug release profiles for uncoated and coated beads were each fitted to appropriate mathematical equations. The drug release from the bead combination dosage form was predicted from the individual mathematical models and verified experimentally in vitro. The in vitro dissolution was conducted in 0.1 N HCl for 2 hr and then in buffer (pH 6.5 phosphate, 0.05 M) to mimic in vivo conditions using USP dissolution apparatus I. The results showed that uncoated beads gave similar release profiles in water, acid, and buffer with complete release within 2 hr. The release from CR beads was about 50% at 10 hr and was independent of the dissolution medium. As expected, enteric coated beads showed drug release < 5% at 2 hr in water and acid, whereas the release in buffer was comparable to that of uncoated beads. Exposure of enteric coated beads to acid for 2 hr produced a slower release rate in buffer compared with the release from beads added directly in the buffer. The release characteristics of the three beads can be described by square root and zero-order kinetics. The release characteristics from the combination dosage form were 39%, 69%, and 81% at 1, 4, and 8 hr, respectively. The experimental and predicted profiles agreed to within +/- 6% (residuals at individual data points). Our results suggest that release from the combined multimechanism oral dosage form can be predicted from the performance of individual beads.

Algorithms↗

PubMed2002

Use of oxygen scavengers to stabilize solid pharmaceutical dosage forms: a case study.

A case study is described where degradation of a solid pharmaceutical dosage form susceptible to oxidation is minimized by incorporation of an oxygen scavenger as part of the packaging. Extremely low oxygen levels are attainable within 24 hr of packaging, even with permeable high-density polyethylene bottles commonly used in the pharmaceutical industry. This packaging methodology allows for a practical formulation-independent pathway for reducing or eliminating oxidative instability. In addition, this technology provides a convenient mechanistic probe for the degradation mechanism of solid dosage forms.

Drug Packaging↗

PubMed1991

Steady-state hydroxyflutamide plasma levels after the administration of two dosage forms of flutamide.

A bioavailability study of randomized cross-over design was carried out in eight volunteers who were given a 48-h flutamide treatment consisting of 250-mg tablets three times daily or 400-mg sustained-release tablets twice daily, followed 3 weeks later by the alternative dosage form. Just before the last dose and 15 times during the subsequent 24 h, blood samples were obtained for the determination of plasma hydroxyflutamide (the active metabolite of flutamide) levels by high-performance liquid chromatography. No statistically significant differences between the two dosage forms were found for the lag time, rate of initial increase in concentration, peak plasma concentration, mean hydroxyflutamide concentration within one dosing interval or 24-h AUC value. One subject presented mild and transient nausea during both treatment periods. After the first treatment period (250-mg tablets), an increase in serum bilirubin was observed in another volunteer, who was withdrawn from the study. It may be concluded that both dosage forms were bioequivalent.

Adult↗