ABSTRACT
The objective of this study was to investigate the influence of various water-soluble additives and HPMCP as an enteric polymer into Surelease for the developement of oral controlled release system containg tamsulosin hydrochloride. The drug loaded pellets were coated with only Surelease or Surelease containing HPMC, PEG 4000, mannitol and HPMCP (20% w/w). In case of HPMC and PEG 4000 as additives into Surelease film, the rapid drug release was observed in pH 1.2 while the higher drug release was achieved by adding HPMCP into Surelease as well as by increasing the amount of HPMCP (10, 20, and 30% w/w) in pH 7.2. The incorporation of HPMCP into Surelease showed pH-denpendent drug release due to its pH-dependent nature. Therefore, the incorporation of HPMCP into Surelease based on aqueous coating formulation is an effective way to develop oral controlled release delivery systems containing tamsulosin hydrochloride.
Subject(s)
Cellulose/analogs & derivatives , Excipients/chemistry , Methylcellulose/analogs & derivatives , Sulfonamides/chemistry , Water/chemistry , Cellulose/chemistry , Delayed-Action Preparations , Drug Compounding , Drug Implants , Methylcellulose/chemistry , Solubility , Tamsulosin , Time FactorsABSTRACT
The cathode in rechargeable lithium-ion batteries operates by conventional intercalation; Li+ is extracted from LiCoO2 on charging accompanied by oxidation of Co3+ to Co4+; the process is reversed on discharge. In contrast, Li+ may be extracted from Mn4+-based solids, e.g., Li2MnO3, without oxidation of Mn4+. A mechanism involving simultaneous Li and O removal is often proposed. Here, we demonstrate directly, by in situ differential electrochemical mass spectrometry (DEMS), that O2 is evolved from such Mn4+ -containing compounds, Li[Ni(0.2)Li(0.2)Mn(0.6)]O2, on charging and using powder neutron diffraction show that O loss from the surface is accompanied by diffusion of transition metal ions from surface to bulk where they occupy vacancies created by Li removal. The composition of the compound moves toward MO(2). Understanding such unconventional Li extraction is important because Li-Mn-Ni-O compounds, irrespective of whether they contain Co, can, after O loss, store 200 mAhg(-1) of charge compared with 140 mAhg(-1) for LiCoO(2).
