PubMed Health⌕ Search

Biomedical subjects

A Sakr

Publications and source records attributed to A Sakr.

28 records · Page 2Linked to original sources
PubMed1993

Effect of mode of incorporation of disintegrants on the characteristics of fluid-bed wet-granulated tablets.

A full factorial experimental design was employed to investigate the effects of mode of disintegrant incorporation and concentration in wet-granulated paracetamol tablets manufactured by top-spray fluid-bed. Disintegrants (croscarmellose sodium, sodium starch glycolate, or crospovidone) were incorporated either intragranularly, extragranularly, or distributed equally between the two phases. The results were analysed by a general quadratic equation and response surfaces generated. On examining the results for dissolution studies the combined mode resulted in significantly faster dissolution rates than did the extragranular mode which, in turn, was superior to the intragranular mode of inclusion. These results were reflected in the disintegration studies where the combined mode exhibited the shortest disintegration times for all the disintegrants. Tablet crushing strength was not affected by the mode of incorporation of concentration of the disintegrants. Main as well as interaction effects between the types, mode of incorporation and percent disintegrant employed were significant (P < 0.05) for disintegration time and percent release at 15 min. Croscarmellose sodium exhibited the shortest while crospovidone displayed significantly (P < 0.05) longer disintegration times. Formulations containing crospovidone did not meet official compendial (USP XXII) requirements of 80% in 30 min. In general, croscarmellose sodium and sodium starch glycolate were found to be less sensitive to the mode of incorporation than crospovidone.

Acetaminophen↗
PubMed1991

Pharmacokinetics and bioavailability of papaverine HCl following intravenous, peroral, rectal, vaginal, topical and buccal administration in beagle dogs.

This in vivo study was designed to obtain bioavailability data and a definite pharmacokinetic profile of papaverine HCl in Beagle dogs following intravenous (IV), peroral (PO), rectal, vaginal, topical, and buccal administration of different papaverine HCl formulations. Blood samples were analyzed by high-performance liquid chromatography. The pharmacokinetic parameters were determined using either a curve fitting program (RESID) or a compartment model independent program (AUC-RPP). The plasma concentration-time profiles show that papaverine HCl pharmacokinetics is best described by an open two-compartment model. The absolute bioavailability of papaverine HCl was determined to be 57.2 per cent, 25.2 per cent, 53.2 per cent, 3.2 per cent and 7.5 per cent, respectively, following P.O., rectal, vaginal, topical and buccal administration.

Administration, Buccal↗
PubMed1991

Biopharmaceutic evaluation of furosemide as a potential candidate for a modified release peroral dosage form.

An attempt was made to evaluate some of the criteria for developing a modified release peroral dosage form for furosemide which has a poor bioavailability when given in the conventional peroral dosage forms. The pathway of absorption for furosemide was studied ex vivo employing the Wilson-Wiseman test. Passive absorption was found to be the predominant mechanism of transport across the ileum of the guinea pig followed by active transport to the extent of about 17%. The in situ procedure to study the extent of absorption of furosemide from the various sites in the lumen of the gastrointestinal tract of the rat indicated the stomach to be the major site of absorption followed by the duodenum. It is hence postulated that due to the site-specificity and mechanism of absorption a peroral modified release dosage form having a longer gastric residence time could possibly increase the bioavailability of furosemide.

Administration, Oral↗
PubMed1991

In vitro/in vivo evaluation of hydrochlorothiazide in experimental hydrochlorothiazide/triamterene combination tablets in beagle dogs.

The purpose of this study was to compare experimental formulations containing hydrochlorothiazide (CAS 58-93-5)/triamterene (HCT/TRI) in vitro and in vivo to a commercial tablet formulation (standard). The beagle dog was verified as a good model and was used for the in vivo studies. The commercial tablet and the experimental fast release formulation (FR) resulted in 100% release of HCT within 30 min in dissolution tests, whereas, the slow release formulation (SR) released only 54% HCT after 4 h. Relative bioavailability of the FR and SR formulations were 82 and 41%, respectively, compared to the commercial tablet. The experimental results indicate that HCT absorption occurs throughout the small intestine.

Animals↗
PubMed1990

In vitro skin absorption and metabolism of benzoic acid, p-aminobenzoic acid, and benzocaine in the hairless guinea pig.

The percutaneous absorption and metabolism of three structurally related compounds, benzoic acid, p-aminobenzoic acid (PABA), and ethyl aminobenzoate (benzocaine), were determined in vitro through hairless guinea pig skin. Benzocaine was also studied in human skin. Absorption of benzocaine was rapid and similar through both viable and nonviable skin. The absorption of the two acidic compounds, benzoic acid and PABA, was greater through nonviable skin. A small portion (6.9%) of absorbed benzoic acid was conjugated with glycine to form hippuric acid. Although N-acetyl-benzocaine had not been observed as a metabolite of benzocaine when studied by other routes of administration, both PABA and benzocaine were extensively N-acetylated during percutaneous absorption. Thus, the metabolism of these compounds should be considered in an accurate assessment of absorption after topical application.

4-Aminobenzoic Acid↗
PubMed1989

Maintenance of skin viability during in vitro percutaneous absorption/metabolism studies.

The assessment of cutaneous metabolism during in vitro percutaneous absorption studies requires maintenance of the viability of the skin section. With the use of flowthrough diffusion cells, Eagle's minimal essential medium (MEM), Hepes-buffered Hanks' balanced salt solution (HHBSS), or Dulbecco modified phosphate-buffered saline (DMPBS), acting as receptor fluids, were able to sustain aerobic and anaerobic glucose utilization, testosterone and estradiol metabolism, and histopathological appearance of perfused rat skin sections for 24 hr. Fetal bovine serum supplements were not required for survival and appeared to inhibit the extraction of the metabolite estrone from the receptor fluid fractions in estradiol absorption/metabolism experiments. The use of phosphate-buffered saline (PBS) resulted in elimination of aerobic and anaerobic glucose utilization in 12 hr and declining appearance of steroid metabolites in receptor fluid fractions during the 24-hr percutaneous absorption/metabolism studies. Histopathological examination of skin sections perfused with PBS for 24 hr showed autolysis of the viable epidermis and dermis. The results demonstrate that an appropriate receptor fluid, such as MEM, HHBSS, or DMPBS, is required for percutaneous absorption studies in which cutaneous metabolism of the penetrating compound is to be considered.

Analysis of Variance↗
PubMed1989

[Augmentation rhinoplasty using bone graft. Technical aspects and therapeutic deductions].

Reviewing 45 cases of augmentation rhinoplasties with bone grafting the authors discuss some technical points and the choices of their indications: donor site, incision, patterns of graft implantation depending on clinical examination which selected the cases where exogenous material from the nose is needed for reconstruction. A columellar support seem to them necessary to correct collapsed noses and in these cases a mortise and tenon joint has been employed. When a pure saddle nose deformity exists, a biomaterial can be used reducing morbidity of an iliac bone graft.

Bone Transplantation↗
PubMedDate not supplied

Pharmacokinetics of papaverine HCl upon intravenous route of administration in old and young beagle dogs.

This in vivo study was designed to compare the pharmacokinetics of papaverine HCl in young and old Beagle dogs following intravenous (i.v.) administration of papaverine HCl. Blood samples were analyzed by high performance liquid chromatography. The pharmacokinetic parameters were first determined using a curve fitting program (RESID), and then evaluated by SAS statistics. The plasma concentration-time profiles show that papaverine HCl pharmacokinetics is best described by an open two-compartment model. The only age-dependent significant difference in pharmacokinetic behavior between young and old Beagle dogs was found concerning the distribution rate constants.

Aging↗