Search results for "dosage"
showing 10 items of 516 documents
Improving Dissolution Behavior and Oral Absorption of Drugs with pH-Dependent Solubility Using pH Modifiers: A Physiologically Realistic Mass Transpo…
2021
Orally dosed drugs must dissolve in the gastrointestinal (GI) tract before being absorbed through the epithelial cell membrane. In vivo drug dissolution depends on the GI tract's physiological conditions such as pH, residence time, luminal buffers, intestinal motility, and transit and drug properties under fed and fasting conditions (Paixao, P. et al. Mol. Pharm. 2018 and Bermejo, et al. M. Mol. Pharm. 2018). The dissolution of an ionizable drug may benefit from manipulating in vivo variables such as the environmental pH using pH-modifying agents incorporated into the dosage form. A successful example is the use of such agents for dissolution enhancement of BCS class IIb (high-permeability,…
Viscosity-mediated negative food effect on oral absorption of poorly-permeable drugs with an absorption window in the proximal intestine: In vitro ex…
2014
Concomitant food intake can diminish oral absorption of drugs with limited permeability and an absorption window in the proximal intestine, due to viscosity-mediated decrease in dosage form disintegration time and drug dissolution rate. Three poorly-permeable drugs (atenolol, metformin hydrochloride, and furosemide) exhibiting negative food effect, and one highly-soluble and highly-permeable (metoprolol tartrate), serving as a negative control, were selected for the study. In vitro and in silico tools were used to evaluate the influence of media viscosity on drug bioperformance under fasted and fed conditions. The obtained results demonstrated that increased medium viscosity in the presence…
Optimised procedures for the reversed-phase liquid chromatographic analysis of formulations containing tricyclic antidepressants.
2003
The chromatographic behaviour (retention, selectivity, peak shape and resolution) of seven tricyclic antidepressants (TCAs), amitryptiline, clomipramine, doxepin, imipramine, maprotiline, nortryptiline and trimipramine, was examined. Conventional unendcapped Cs and C18 columns and an endcapped XTerra MS C18 column recommended for the analysis of basic compounds were used together with acetonitrile-water and micellar sodium dodecylsulfate (SDS)-pentanol mobile phases. The two best combinations were XTerra C18/acetonitrile, which yielded the largest efficiencies and resolution, and C8/SDS-pentanol, which eliminated the peak tails that were still observed with the XTerra C18 column. Both the s…
Evaluation of Antimicrobial Activity of Triphala Constituents and Nanoformulation
2020
The prevalence of nosocomial infections due to multidrug resistant (MDR) bacterial strains is associated with high morbidity and mortality. Folk medicine and ethnopharmacological data can provide a broad range of plants with promising antimicrobial activity. Triphala, an Ayurvedic formula composed of three different plants: Terminalia chebula Retz., Terminalia bellirica (Gaertn.) Roxb. (Combretaceae), and Phyllanthus emblica L. (Phyllanthaceae), is used widely for various microbial infections. Various extraction techniques were applied in the extraction of the biologically active constituents of Triphala in order to compare their efficiency. Microwave-assisted extraction (MAE) was shown to …
Trehalose-hydroxyethylcellulose microspheres containing vancomycin for topical drug delivery.
2001
Abstract A new formulation, in which vancomycin is entrapped into trehalose and hydroxyethylcellulose (Natrosol ® ) spherical matrices, is described. Microspheres were produced by the solvent evaporation method. The entrapped drug was fully recovered following microspheres dissolution. Differential scanning calorimetry analyses proved that Natrosol maintains trehalose in its amorphous form. The stabilizing effects of trehalose on vancomycin were evaluated even after long storage and heating of microspheres. Calorimetric data indicated no decomposition of the entrapped drug. In vitro drug release, already performed by using a general two-compartment linear time-invariant open model, suggests…
Pefloxacine mesilate- and ofloxacin-loaded polyethylcyanoacrylate nanoparticles: characterization of the colloidal drug carrier formulation.
1995
The entrapment of fluoroquinolones, perfloxacine mesilate (PFX) and ofloxacin (OFX), in polyalkylcyanoacrylate (PECA) nanoparticles could offer some advantages for their biological application; for examples, increasing their bioavailability, controlling the drug time-release in blood, and reducing the formation of bacterial resistance. To load these two drugs in PECA polymeric bulk, the incorporation or adsorption method was performed. These two methods were capable of influencing nanoparticle size, molecular weight, release profile, and drug–polymer association. The incorporation method, particularly for the OFX system, achieved PECA nanoparticle suspensions with a mean size value three ti…
Dry adsorbed emulsion: 1. Characterization of an intricate physicochemical structure
2000
Abstract A recent solid pharmaceutical form called “Dry Adsorbed Emulsion” (DAE) was characterized in morphological and structural fields. A DAE is an intricate system initiated by a water‐in‐oil emulsion including the active drug (i.e., theophylline). Each emulsion phase is adsorbed on pulverulent adsorbents with a suitable polarity (silica) to obtain a free‐flowing powder with nonporous particles of size from 125 to 710 μm, with small specific surface area and a spherical shape. Different methods, such as scanning electron microscopy combined with chemical microanalysis, dying tests, and electron spin resonance studies, allow the formulator to follow the behavior of DAE aqueous and oily p…
Comparative genetic study of intratumoral heterogenous MYCN amplified neuroblastoma versus aggressive genetic profile neuroblastic tumors.
2016
Intratumoral heterogeneous MYCN amplification (hetMNA) is an unusual event in neuroblastoma with unascertained biological and clinical implications. Diagnosis is based on the detection of MYCN amplification surrounded by non-amplified tumor cells by fluorescence in situ hybridization (FISH). To better define the genetic features of hetMNA tumors, we studied the Spanish cohort of neuroblastic tumors by FISH and single nucleotide polymorphism arrays. We compared hetMNA tumors with homogeneous MNA (homMNA) and nonMNA tumors with 11q deletion (nonMNA w11q-). Of 1091 primary tumors, 28 were hetMNA by FISH. Intratumoral heterogeneity of 1p, 2p, 11q and 17q was closely associated with hetMNA tumor…
Relapse Analysis of Irradiated Patients Within the HD15 Trial of the German Hodgkin Study Group
2015
Purpose To determine, in the setting of advanced-stage of Hodgkin lymphoma (HL), whether relapses occur in the irradiated planning target volume and whether the definition of local radiation therapy (RT) used by the German Hodgkin Study Group (GHSG) is adequate, because there is no harmonization of field and volume definitions among the large cooperative groups in the treatment of advanced-stage HL. Methods and Materials All patients with residual disease of ≥2.5 cm after multiagent chemotherapy (CTX) were evaluated using additional positron emission tomography (PET), and those with a PET-positive result were irradiated with 30 Gy to the site of residual disease. We re-evaluated all sites o…
Radiation dose distribution in functional heart regions from tangential breast cancer radiotherapy
2015
Abstract Background and purpose To analyze the distribution of individually-determined radiation dose to the heart and its functional sub-structures after radiotherapy in breast cancer patients treated in Germany during 1998–2008. Material and methods We obtained electronic treatment planning records for 769 female breast cancer patients treated with megavoltage tangential field radiotherapy. All dose distributions were re-calculated using Eclipse with the anisotropic analytical algorithm (AAA) for photon fields, and the electron Monte Carlo algorithm for electron boost fields. Based on individual dose volume histograms for the complete heart and several functional sub-structures, we estima…