Abstract. Self-emulsifying pellets were prepared using microcrystalline cellulose, emulsions of caprylic/ capric triglyceride, and three Cremophors (ELP, RH40, and RH60) at 1.5 and 2.3 weight ratios, and two drugs (furosemide and propranolol) of different lipophilicity. Droplet size, zeta potential (ζ) and viscosity of emulsions, and pellet size, shape, friability, tensile strength, disintegration, and drug migration in pellets were determined. Evaluation of reconstituted emulsions was based on droplet size and ζ. Factorial design and 3-way ANOVA was applied to estimate the significance of the effects of the drug, surfactant and oil/ surfactant ratio. It was found that droplet size, viscosity and ζ of emulsions, and size, shape, and friability of pellets were affected by the studied factors and were significant interactions between their effects on pellet size and friability. Migration of drug towards the pellet surface was higher for the less lipophilic furosemide and higher oil content. Linear relationships were found between the emulsion viscosity and the shape parameters of the pellets (for the aspect ratio R 2 =0.796 for furosemide and R 2 =0.885 for propranolol and for the shape factor, e R R 2 =0.740 and R 2 =0.960, respectively). For all the formulations examined, an exponential relationship was found between migration (M%) and the product of viscosity (η) and solubility of drug in oil/surfactant mixture (S) (M%=98.1e-0.016 [η•S], R 2 =0.856), which may be useful in formulation work.KEY WORDS: drug distribution; emulsion and pellet characterization; friability and tensile strength; furosemide and propranolol; self-emulsifying pellets.
CAMH and Lutrol have different reactivities towards venlafaxine HCl and also different plasticising mechanisms for Eudragit RSPO because of hydrogen bonding and because of similar overall molecular attractive forces, respectively.
A B S T R A C TDiprophyl I ine release from glycerol palm i to-stearate "precirol" matrices containing different direct compression (DC) excipients, with variable dissolving/disintegrating ability, is investigated. The matrices are formed by employing dry-heat granulation and compression at elevated temper at ure.Greater drug release prolongation is achieved with the dissolving DC excipients than with the swelling ones. The release is described on the basis of two bi-exponential f i r s t order models and the Weibull function as well.The effect of compression conditions (temperature and pressure) on the drug release is found t o be related t o the compaction behaviour of the DC excipients, i .e. plastic deformation or fragmentation.
I N T R O D U C T I O NGlycerol palmito-stearate ltpreciroitV is a low melting point material which has been used for the preparation of sustained release dosage forms, both inert and erodible matrices, for oral administration. Diprophylline (Rorer, East Sussex, G.B.) was selected as the model drug entity. Glycerol palmito-stearate (Precirol A T 0 5, m.p.
Materials
52-55OC,Gattefossb, St. Priest, France) was the main matrix forming material, Both these materials were utilized a t a 33.3% level. A t the same level (33.3% by weight) the following DC excipients were added: spray dried hydrous lactose, SDL, (DMV, Veghel, The Netherlands); Emdex, which is dextrates in hydrated form (Edward Mendell, Drug Development and Industrial Pharmacy Downloaded from informahealthcare.com by University of Calgary on 10/17/12For personal use only.
Lutrol F127 and citric acid are efficient plasticizers and Lutrol F127 is a thermal binder/lubricant in HC compression. The different bonding mechanisms of the matrices were reflected in the mechanical strength and drug release. Relationships established between T and drug release parameters for HME and HC matrices may be useful during formulation work.
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