Department of Pharmaceutics and Pharmaceutical Technology, Olabisi Onabanjo University, Sagamu, Nigeria.
AAPS PharmSciTech. 2012 Mar;13(1):16-23. doi: 10.1208/s12249-011-9712-0. Epub 2011 Nov 9.
The exudates from the incised trunk of Terminalia randii has been evaluated as controlled release excipient in comparison with xanthan gum and hydroxypropylmethylcellulose (HPMC) using carvedilol (water insoluble) and theophylline (water soluble) as model drugs. Matrix tablets were prepared by direct compression and the effects of polymer concentration and excipients-spray dried lactose, microcrystalline cellulose and dicalcium phosphate dihydrate on the mechanical (crushing strength (CS) friability (F) and crushing strength-friability ratio (CSFR)) and drug release properties of the matrix tablets were evaluated. The drug release data were fitted into different release kinetics equations to determine the drug release mechanism(s) from the matrix tablets. The results showed that the CS and CSFR increased with increase in polymer concentration while F decreased. The ranking of CS and CSFR was HPMC > terminalia > xanthan while the ranking was reverse for F. The ranking for t(25) (i.e. time for 25% drug release) at a polymer concentration of 60% was xanthan > terminalia = HPMC. The dissolution time, t(25), of theophylline matrices was significantly lower (p < 0.001) than those of carvedilol matrix tablets. Drug release from the matrices was by swelling, diffusion and erosion. The mechanical and drug release properties of the tablets were significantly (p < 0.05) dependent on the type and concentration of polymer and excipients used with the release mechanisms varying from Fickian to anomalous. Terminalia gum compared favourably with standard polymers when used in controlled release matrices and could serve as a suitable alternative to the standard polymers in drug delivery.
用辛可宁（水不溶性）和茶碱（水溶性）作为模型药物，评价了使君子切伤树干的渗出物作为控释赋形剂，与黄原胶和羟丙基甲基纤维素（HPMC）相比。通过直接压缩制备基质片剂，并考察了聚合物浓度以及赋形剂-喷雾干燥乳糖、微晶纤维素和二水磷酸二钙对基质片剂的机械性能（抗压强度（CS）、脆碎度（F）和抗压强度-脆碎度比（CSFR））和药物释放性能的影响。将药物释放数据拟合到不同的释放动力学方程中，以确定药物从基质片剂中的释放机制。结果表明，随着聚合物浓度的增加，CS 和 CSFR 增加，而 F 降低。CS 和 CSFR 的排序为 HPMC>使君子>黄原胶，而 F 的排序则相反。聚合物浓度为 60%时 CS 和 CSFR 的排序为黄原胶>使君子=HPMC。茶碱基质的溶出时间，t（25）（即 25%药物释放的时间）明显低于卡维地洛基质片剂（p<0.001）。药物从基质中的释放是通过溶胀、扩散和侵蚀。片剂的机械性能和药物释放性能与聚合物和赋形剂的类型和浓度显著相关（p<0.05），释放机制从菲克扩散到反常扩散。使君子胶与标准聚合物相比，在控释基质中具有优势，可作为药物传递中标准聚合物的合适替代品。
