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The objective of the present study was to develop once-daily sustained-release matrix tablets of nicorandil, a novel potassium
channel opener used in cardiovascular diseases. The tablets were prepared by the wet granulation method. Ethanolic solutions
of ethylcellulose (EC), Eudragit RL-100, Eudragit RS-100, and polyvinylpyrrolidone were used as granulating agents along with
hydrophilic matrix materials like hydroxypropyl methylcellulose (HPMC), sodium carboxymethylcellulose, and sodium alginate.
The granules were evaluated for angle of repose, bulk density, compressibility index, total porosity, and drug content. The
tablets were subjected to thickness, diameter, weight variation test, drug content, hardness, friability, and in vitro release
studies. The granules showed satisfactory flow properties, compressibility, and drug content. All the tablet formulations
showed acceptable pharmacotechnical properties and complied with in-house specifications for tested parameters. According
to the theoretical release profile calculation, a oncedaily sustained-release formulation should release 5.92 mg of nicorandil
in 1 hour, like conventional tablets, and 3.21 mg per hour up to 24 hours. The results of dissolution studies indicated that
formulation F-I (drug-to-HPMC, 1∶4; ethanol as granulating agent) could extend the drug release up to 24 hours. In the further
formulation development process, F-IX (drug-to-HPMC, 1∶4; EC 4% wt/vol as granulating agent), the most successful formulation
of the study, exhibited satisfactory drug release in the initial hours, and the total release pattern was very close to the
theoretical release profile. All the formulations (except F-IX) exhibited diffusion-dominated drug release. The mechanism
of drug release from F-IX was diffusion coupled with erosion. 相似文献
2.
An oral press-coated tablet was developed by means of direct compression to achieve the time-controlled disintegrating or
rupturing function with a distinct predetermined lag time. This press-coated tablet containing sodium diclofenac in the inner
core was formulated with an outer shell by different weight ratios of hydrophobic polymer of micronized ethylcellulose (EC)
powder and hydrophilic excipients such as spray-dried lactose (SDL) or hydroxypropyl methylcellulose (HPMC). The effect of
the formulation of an outer shell comprising both hydrophobic polymer and hydrophilic excipients on the time lag of drug release
was investigated. The release profile of the press-coated tablet exhibited a time period without drug release (time lag) followed
by a rapid and complete release phase, in which the outer shell ruptured or broke into 2 halves. The lag phase was markedly
dependent on the weight ratios of EC/SDL or EC/HPMC in the outer shell. Different time lags of the press-coated tablets from
1.0 to 16.3 hours could be modulated by changing the type and amount of the excipients. A semilogarithmic plot of the time
lag of the tablet against the weight ratios of EC/SDL or EC/HPMC in the outer shell demonstrated a good linear relationship,
withr=0.976 andr=0.982, respectively. The predetermined time lag prior to the drug release from a press-coated tablet prepared by using a
micronized EC as a retarding coating shell can be adequately scheduled with the addition of hydrophilic excipients according
to the time or site requirements. 相似文献
3.
The objective was to investigate the suitable polymeric films for the development of diltiazem hydrochloride (diltiazem HCl)
transdermal drug delivery systems. Hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) were used as hydrophilic and
hydrophobic film formers, respectively. Effects of HPMC/EC ratios and plasticizers on mechanical properties of free films
were studied. Effects of HPMC/EC ratios on moisture uptake, in vitro release and permeation through pig ear skin of diltiazem HCl films were evaluated. Influence of enhancers including isopropyl
myristate (IPM), isopropyl palmitate (IPP), N-methyl-2-pyrrolidone, oleic acid, polyethylene glycol 400, propylene glycol, and Tween80 on permeation was evaluated. It
was found that addition of EC into HPMC film produced lower ultimate tensile strength, percent elongation at break and Young’s
modulus, however, addition of EC up to 60% resulted in too hard film. Plasticization with dibutyl phthalate (DBP) produced
higher strength but lower elongation as compared to triethyl citrate. The moisture uptake and initial release rates (0–1 h)
of diltiazem HCl films decreased with increasing the EC ratio. Diltiazem HCl films (10:0, 8:2 and 6:4 HPMC/EC) were studied
for permeation because of the higher release rate. The 10:0 and 8:2 HPMC/EC films showed the comparable permeation-time profiles,
and had higher flux values and shorter lag time as compared to 6:4 HPMC/EC film. Addition of IPM, IPP or Tween80 could enhance
the fluxes for approx. three times while Tween80 also shorten the lag time. In conclusion, the film composed of 8:2 HPMC/EC,
30% DBP and 10% IPM, IPP or Tween80 loaded with 25% diltiazem HCl should be selected for manufacturing transdermal patch by
using a suitable adhesive layer and backing membrane. Further in vitro permeation and in vivo performance studies are required. 相似文献
4.
The purpose of this research was to investigate the interaction of water with ethylcellulose samples and assess the effect
of particle size on the interaction. The distribution of water within coarse particle ethylcellulose (CPEC; average particle
size 310 μm) and fine particle ethylcellulose (FPEC; average particle size 9.7 μm) of 7 cps viscosity grade was assessed by
differential scanning calorimetry (DSC) and dynamic vapor sorption analysis. The amounts of nonfreezing and freezing water
in hydrated samples were determined from melting endotherms obtained by DSC. An increase in water content resulted in an increase
in the enthalpy of fusion of water for the two particle size fractions of EC. The amount of nonfreezable water was not affected
by the change in particle size at low water contents. Exposure of ethylcellulose to water for 30 minutes is sufficient to
achieve equilibration within the hydrated polymer at 47% wt/wt water content. The moisture sorption profiles were analyzed
according to the Guggenheim-Anderson-de Boer (GAB) and Young and Nelson equations, which can help to distinguish moisture
distribution in different physical forms. The amount of externally adsorbed moisture was greater in the case of FPEC. Internally
absorbed moisture was evident only with the CPEC. In light of these results, and explanation is offered for the success of
FPEC in wet-granulation methods where CPEC was not successful. 相似文献
5.
This work was aimed at evaluating the effect of a pharmaceutical cationic exchange resin (Amberlite IRP-69) on the properties
of controlled release matrices using Methocel K4M (HPMC) or Ethocel 7cP (EC) as matrix formers. Diphenhydramine hydrochloride
(DPH), which was cationic and water soluble, was chosen as a model drug. HPMC- and EC-based matrices with varying amounts
(0–40%w/w) of resin incorporation were prepared by a direct compression. Matrix properties including diameter, thickness, hardness,
friability, surface morphology and drug release were evaluated. The obtained matrices were comparable in diameter and thickness
regardless of the amount of resin incorporation. Increasing the incorporated resin decreased the hardness of HPMC- and EC-based
matrices, correlating with the degree of rupturing on the matrix surfaces. The friability of HPMC-based matrices increased
with increasing the incorporated resin, corresponding to their decreased hardness. In contrast, the EC-based matrices showed
no significant change in friability in spite of decreasing hardness. The incorporated resin differently influenced DPH release
from HPMC- and EC-based matrices in deionized water. The resin further retarded DPH release from HPMC-based matrices due to
the gelling property of HPMC and the ion exchange property of the resin. In contrast, the release from EC-based matrices initially
increased because of the disintegrating property of the resin, but thereafter declined due to the complex formation between
released drug and dispersed resin via the ion exchange process. The release in ionic solutions was also described. In conclusion, the incorporated resin could alter the release and physical properties of matrices. 相似文献
6.
The effect of concentration of hydrophilic (hydroxypropyl methylcellulose [HPMC]) and hydrophobic polymers (hydrogenated castor
oil [HCO], ethylcellulose) on the release rate of tramadol was studied. Hydrophilic matrix tablets were prepared by wet granulation
technique, while hydrophobic (wax) matrix tablets were prepared by melt granulation technique and in vitro dissolution studies
were performed using United States Pharmacopeia (USP) apparatus type II. Hydrophobic matrix tablets resulted in sustained
in vitro drug release (>20 hours) as compared with hydrophilic matrix tablets (<14 hours). The presence of ethylcellulose
in either of the matrix systems prolonged the release rate of the drug. Tablets prepared by combination of hydrophilic and
hydrophobic polymers failed to prolong the drug release beyond 12 hours. The effect of ethylcellulose coating (Surelease)
and the presence of lactose and HPMC in the coating composition on the drug release was also investigated. Hydrophobic matrix
tablets prepared using HCO were found to be best suited for modulating the delivery of the highly water-soluble drug, tramadol
hydrochloride. 相似文献
7.
Summary and Conclusion This study investigated the effect of some commonly used release enhancers on the compaction characteristics of EC. The wet
granulation method of massing and screening was used, and compacts were produced by compressing granules for 60 seconds at
various compression pressures. The Heckel equation, used for the analysis of results, showed that EC alone showed better compressibility
than formulations with additives. The hygroscopic additives, sorbitol and PEG 4000, produced unusual Heckel plots, while the
nonhygroscopic additives, PEG 10 000 and mannitol, produced biphasic Heckel plots. The results also indicate that EC alone
exhibited the highest degree of packing in the die, with the addition of mannitol reducing the extent of packing the most.
The presence of additives in EC for-mulations increased the pressures at which plastic deformation of EC granules occurred.
The extent of this depended on the type of additive, with mannitol imparting the highest resistance to deformation of EC granules
and sorbitol the lowest. It can be concluded that additives such as PEG 4000, PEG 10 000, sorbitol, and mannitol, which are
often used as channeling agents in sustained-release formulations containing hydrophobic matrix formers, affect the deformation
characteristics of EC, with the extent and nature of the effect dependent on the nature of the additive.
Published: July 14, 2006 相似文献
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