| fatty base (cocoa butter) | cocoa butter substitutes | glycero-gelatin | Macrogols | |
| composition | 1-triglycerides :oleopalmitostearin & oleodistearin ,I2 value 34-38 ;full of unsat FA ,acid value not more than 4 | veg. Oil as coconut or palm kernel oil modified by 1-estrification > glycerol + fats 2-hydrogenation of fatty acids (lauric acid) 3-fractionation and re- estrification with xxs glycerin | gelatin + glycerin + water in egypt 18% gelatin in enfland 14% in usa 20% | water sol supp from macrogol bases (PEG) ,choose suitable admixture |
| disadvantages | 1-overheating :causes polymorphism ,prevented by :minimal use oh heating in melting process 2-low contractility during solidification (prevent by use lubricant) 3-rancidity 4-melt in hot weather 5-liquefy when incorporated with another rdrugs (v.o ,cresol ,phenol ,chloral hydrate ) (-) m.p (prevent by wax and spermaceti) 6-not takes up large quantities of water (prevent using SAA tween 61 + water abs) | 1-should be cooled in refrigerator or ice because they become brittle if cooled quickly (certain additives as 0.05% polysorbate can be used to correct this fault 2-more fluid than cocoa butter when melted so sedimentation is great (prevent by using thickening agent such Mg-stearate ,bentonite and colloidal silicon oxide | 1- they are hygroscopic need careful storage (affect drugs and phase of M.O) leads to dehydration of anorectal membrane e irritation (and laxative effect is requred) prevent by dipping in water before insertion 2-they have physiological action {laxative } not give time enough for abs of drug 3-they are more difficult to prep and handle (due to air bubbles) 3-gelatin is incompatible e protein pptes as tannic acis. 4-soln depends on content and quality of gelatin (pharmagel A & pharmagel B) | 1-they are hygroscopic need careful storage (affect drugs and phase of M.O) leads to dehydration of anorectal membrane e irritation (and laxative effect is requred) prevent by dipping in water before insertion or incorporate 20% of water in mass 2-sometimes fructure occurs & irritation and (-) abs due to crystal formation asit is high sol can leads to super sat soln > crystallization 3-incompatible e Bi salts ,tannins ,phenol and liquifaction occur e tannins and phenol 4-lower act of some antimicrobial agents 5-dissolve certain plastics (put in teflon) |
| advantages | 1-innocuous (not viscous) 2-melt at body temp 3-solid. Pt bet 12-13 as not reach to complete melt 4-emuls. Can be added as it has low water solubility (5-10% tween 61) 5-+ conc of sol sub in fat - melt temp till eutectic pt is reached 6-mats as Al monostearate or silica can added w give melted fat thixotropic properties 7-addn of subs + M.temp from eutectic pt to m.p A-white wax > in 3% will give mix have lower M.temp B: white wax 6% raise M.temp of cocoa wax mix | 1-solid.pt not affected by over heating 2-good resistance for oxdn 3-diif bet M.pt & seting pt is small (slippery )>1.5-2 risk of sedimentation is low 4-usu contain proportion of monotriglycerides o/w am.agents > so em and water abs capasity are good 5-no mold lubricant is needed | 1-have M.pt above 42 ,hence cool storage not required ,satisfactory in hot climate , easy admins as it is not slippery 2-not melt in body > gradual dissolve and dieperse > freeing of medication slowly (vaginal use) 3-physical properties differ as we use admixture or add plasticisers 4-abs water well and exellent solvent properties 5-it has high m.wt and high viscosity so no need of use thickining agent. | |