ABSTRACT
In this study, the efficiency of using force control agents [FCAs] namely Polyethylenglycol 6000 [PEG] andpolyvinylpyrrolidone [povidone k-30][PVP] and Sodium lauryl sulfate [SLS] in modifying the surface of lactosewere invisitigated. Lactose surface was modified by sinking within aqueous solution containing one of eachmentioned FCAs. The surface free energies of FCAs unprocessed lactose and processed lactose powders weremeasured using contact angle measurements. Results showed high negative spreading cofficient[lamda[12]] of SLSover lactose which expalins the disability of SLS to adhere to the surfaces of lactose. On other hand, a positive[lamda[12]] value of PVP enabled its adherence to lactose surfaces and so to modify the surface energy to a significantextent. These changes were furthermore observed in case of PEG which had the highest [lamda[12]] compared to others.It is concluded that the more positive the spreading coefficient of a FCA over lactose, the higher the ability of theFCA to modify the surface of lactose is. Also the cohesion works of the powders were directly correlated to theCarr's index and Hausner ratio which are used as indictors of the flow ability. It was also found that all themodified surface lactose powders had surface free energy and cohesion work less than the original lactose.Therefore, surface free energy data can be used as a predict tool to screen for the suitable FCA for each carrier.DSC and FT-IR confirmed the absence of any significant interaction between FCAs and lactose
ABSTRACT
Spray drying techniques are used to produce inhaled powders of enzymes and proteins without denaturation. The surface free energy data of these powders is used to reduce the time of formulation development. During storage, the surface free energy of the inhaled protein powders could change and so their performance will be affected. Many factors affect the limit of this change. Storage temperature is the critical factor. A spray drying method was optimized to prepare inhaled spray dried lysozyme powders. Inverse gas chromatography was utilized to measure the surface free energy of the prepared powders pre and post-storage to detect the effect of storage temperature on the surface free energy. Differential Scanning Calorimetry and biological activity tests were used to evaluate the integrity of lysozyme conformation after storage at different storage temperature. Increasing the storage temperature decreased both dispersive and specific surface components of the spray-dried lysozyme powders significantly [ANOVA: P < 0.001] up to 12% and up to 31% after storage for one year at 40 degree C, respectively. The overall decrease in the polar components resulted in a reduction of the surface basicity. These decreases in the surface energetics would be due to the aggregation of denatured lysozyme molecules at the powder surface via hydrophobic regions rich with electrons. The same results were found after storage for one year at room temperature, but the extents of changes were smaller. It is advisable to store protein powders at 5 degree C to inhibit the changes in their surface free energy which is the crucial factor affecting their performance
ABSTRACT
The drug dissolution rate is considered to be one of the most important physiochemical characteristics that researchers try hardly to improve it based, on its relations with bioavailability and efficiency as a result. Felodipine [FEL] is one of the poorly soluble drugs [about 0.5 microg/ml]. Therefore, physical mixtures [PM] of Felodipine was prepared with hydrophilic polymers like Polyethylene glycol 6000 [PEG] and Polyvinylpyrrolidone [PVP] with ratio 1:1, 1:5, 1:10, 1:15. Also, a surfactant adding was studied [which is Poloxamer 407 [POL]] to the following, physical mixtures PM 1:15 FEL:PEG, PM 1:15 FEL:PVP in order to study their effect on the dissolution rate of Felodipine and its interactions with both polymers PEG and PVP and also to study the effects of this interaction on the swelling of hydrogel which made by POL subsequently its effects on the dissolution rate of Felodipine. For studying the effects of mechanical activation on the dissolution rate of the Felodipine, four physical mixtures were selected and made as Slug [S] then Milled [M] to obtain the powder of Slugg [SM] then the SM powder was compressed to obtain the final tablet [SM + S]. The result of research showed a slight improvement in the dissolution rate of Felodipine in case of PM, but it was more obvious because of SM and SM + S process. Also the result of dissolution rate showed the effect of both polymers PEG or PVP on the thickness of hydrogel which surfactant [POL] formed it, i.e the effect of polymer -surfactant interaction on the dissolution rate of FEL