PubMed Health⌕ Search

Biomedical subjects

M A Bayomi

Publications and source records attributed to M A Bayomi.

5 recordsLinked to original sources
PubMed2003

Influence of polymers weight ratio and pH of polymers solution on the characteristics of chitosan-carboxymethyl cellulose microspheres containing theophylline.

Optimization of formulation for chitosan-carboxymethyl cellulose (CH-CMC) microspheres that contain a drug of narrrow therapeutic index was the interest of this study. Theophylline (TPH) was chosen as a model drug. The effects of chitosan:sodium carboxymethyl cellulose (CH:SCMC) weight ratio (X1) and pH of polymers solution (X2) as independent variables on the physical characteristics of the microspheres as well as release profile of TPH from microspheres prepared by the emulsion coacervation-phase separation technique were studied. The influence of each of the two variables on responses such as angle of repose, compressibility index, incorporation efficiency particle size, initial drug release, time for 50% drug release (T50%) and % drug released in 8 hours was investigated. Generally, the increase in CH:SCMC weight ratio showed to increase the incorporation efficiency of the drug, increase the particle size and decrease the flowability of the microspheres. The increase of CH:SCMC ratio was also responsible to get low initial drug release, slow drug release (long T50%) and incomplete total drug released in 8 hours. On the other hand, high and low pHs of polymers solution were responsible to decrease drug incorporation in the microspheres and to produce small particles while, good flowability was obtained at pHs 2.5 and 4. A full factorial experimental design was employed to investigate the effect of the two independent variables on the responses. The results were analyzed by a general quadratic equation and response surfaces generated. From the obtained regression, it was concluded that the effect of CH:SCMC polymers ratio is more significant in changing the values of flowability particle size and drug release in 8 hours while pH values were more significant in changing the values of initial drug release and T50%. On the other hand the interaction coefficients of the two variables showed synergistic effect on flowability and drug release in 8 hours while, there were antagonist effects on particle sizes and T50%. From the optimization studies it is possible to choose the conditions required for the preparation of microspheres with the desired characteristics.

Bronchodilator Agents↗
PubMed2001

Excipient-excipient interaction in the design of sustained-release theophylline tablets: in vitro and in vivo evaluation.

Sustained-release (SR) theophylline (TPH) tablets were prepared by applying the moisture-activated dry granulation method. The interaction between the excipients sodium alginate (SAL) and calcium gluconate (CG) was the base for the formation of a cross-linked matrix that may regulate TPH release from the formulated tablets. The prepared granules showed good physical characteristics concerning the flow properties and compressibility, with the angles of repose in the range 29-31, and the compressibility indices ranged between 15% and 25%. The granules had low friability values (3.0%-4.2%), depending on SAL:CG ratios. The corresponding tablets showed good physical properties, with a lower rate of drug release compared with the commercial TPH tablets (Quibron). The release of TPH from the prepared tablets was not markedly affected by either the concentration of added dry binder (carbopol 934) or the tablet hardness, indicating that the rate-determining step in drug release was the diffusion through the produced calcium alginate matrix. Tablets formulated with equal ratios of CG and SAL that showed good physical properties and slow TPH release were chosen for bioavailability studies in beagle dogs, and results were compared with those for Quibron. The in vivo data showed a comparable plasma concentration profile for both tablet formulations, with prolonged appearance of drug in the plasma in detectable amounts for up to 24 h. The formulated tablets showed 104.65% bioavailability relative to that of the commercial tablets. The rate and extent of absorption of TPH showed no significant differences from that of the commercial tablets. Moreover, no significant differences were found in the pharmacokinetic parameters related to the rate and extent of TPH absorption from the prepared and commercial tablets.

Alginates↗
PubMed1998

Preparation of casein-chitosan microspheres containing diltiazem hydrochloride by an aqueous coacervation technique.

Sustained release casein-chitosan microspheres containing diltiazem hydrochloride (DTZ) were prepared with colloidal coacervation technique in a completely aqueous environment. The interaction between chitosan solution in dilute acetic acid (5% v/v) and casein solution in 0.5 M sodium hydroxide was the basis for the microspheres formation. Formaldehyde was used for the surface hardening of the droplets by cross-linking and thus fixing the shape and surface morphology of the formed microspheres. The entrapment efficiencies of the microspheres were variables (14.5-53.7%) depending on the preparation conditions. The prepared microspheres exhibited an angle of repose values between 31.9-42.0 degrees indicating good free flowing nature, whereas DTZ powder as such was non-flowable. The dissolution profiles of DTZ from casein-chitosan microspheres showed retarded release pattern of the drug into distilled water. Casein and chitosan concentrations, initial drug concentration and stirring time were found to be the main parameters that affect the properties and the performance of the prepared microspheres. The retarded release of DTZ was increased by increasing casein concentration, and stirring time. On the other hand, increasing chitosan concentration and using high initial drug loading showed a fast drug release.

Animals↗
PubMed1991

Piroxicam-natural polymers interactions.

The interaction of the anti-inflammatory drug, piroxicam, with some naturally occurring polymers-viz gamma-globulin, bovine serum-albumin, bovine synovial fluid and casein was characterized in this study. This was done using equilibrium dialysis method where the dialysis membrane was permeable only to the drug molecules while polymers and formed complex(es) cannot pass through. The amount of permeable piroxicam molecules was determined spectrophotometrically. It was found out that increasing the concentration of piroxicam was accompanied by an increase in the amount of piroxicam bound to the investigated natural polymers. The maximum binding capacity of the investigated polymers for the drug as revealed by Langmuir plots, could be arranged in ascending manner as follows: synovial fluid, albumin, casein and gamma-globulin. The binding parameters K (association constant) and n (the number of binding sites available on the polymer) were determined using Sandberg plots. It was found that two classed of binding sites were involved in the interaction of piroxicam with gamma-globulin, albumin and casein. Increasing salt concentration was accompanied by a decrease in piroxicam binding with the investigated polymers till a constant value of ionic strength (0.6 mole/liter). This result may suggest the ionic nature in binding of piroxicam with the investigated polymers. It was concluded that piroxicam is strongly bound to the investigated natural polymers with different degree of binding, such binding may affect the pharmacological effect of piroxicam. An in-vivo absorption study was performed on eight male healthy volunteers to compare the bioavailability of piroxicam in presence and absence of casein using plasma data after 100 mg single dose treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗