FORMULATION AND EVALUATION OF EXTENDED RELEASE MICROCAPSULES OF LAMIVUDINE - REVIEW OF LITERATURE

 

REVIEW OF LITERATURE

 

            Literature review shows that no work has been published on the extended release micro capsule of Diltiazem HCL. Some of the published reports of similar work for various medicinal agents are:

 

v      Samal et al. developed oral sustained release matrix tablets of an antiretroviral drug, zidovudine. Matrix tablets were prepared by wet granulation method using various proportions of hydrophilic polymers like Sodium CMC, HPMC, Eudragit‐L155, & Xanthan gum along or in combination with hydrophobic polymer ethyl cellulose.  The release kinetics was analyzed using zero order, first order, Higuchi and Hixson Crowell model. From this study it was concluded that presence of sodium CMC gives zero‐order release kinetics and the linearity ranges from 0.990 to 0.996. It has also good drug entrapment efficiency ranging from 96 to 106% of drug. Formulation containing sodium CMC with Xanthan gum and EC gives sustained release for drug more than 12hrs.10

 

v      Atul Kuksal et al., prepared extended-release matrix tablets of anti retroviral drug, zidovudine using hydrophilic polymers Eudragit RLPO and RSPO alone or in combination with hydrophobic polymer Ethyl cellulose. The in-vitro drug release study revealed that either Eduragit preparation was able to sustain the drug release only for 6 hours (94.3% ± 4.5%release). Combining Eudragit with ethyl cellulose sustained the drug release for 12 hours (88.1% ± 4.1% release). ¹¹

 

v      Patel Sunilkumar et al., formulated sustained release matrix of NSAID ibuprofen by using matrix polymer HPMC and ethyl cellulose alone and in combination. Drug release study was carried out using BP apparatus 2 in  pH 7 buffer for 12 hr at 1 hr sampling interval.  The results of dissolution study concluded that the release of drug from matrix prepared from different ratios of both HPMC and EC gets more retarded than from HPMC and EC alone.¹²

 

v      Subramaniam Kannan et al., developed sustained release tablets of NSAID, aceclofenac  (200mg) by wet granulation using hydrophilic polymer like Hydroxy propyl methyl cellulose K -100. They showed the drug release from optimized formulations was extended for a period of 24 hrs. The kinetic treatment of selected formulations showed that the release of drug follows zero order models. This study indicated the suitability of hydrophilic polymers in the preparation of matrix based sustained release formulations of NSAID.¹³

 

v      SC Basak et al., prepared Monolithic matrix tablets of ambroxol hydrochloride, formulated as sustained release tablets employing Hydroxy propyl methyl cellulose polymer by direct compression process.  The results of dissolution studies indicated that formulation containing drug to polymer in the ratio of 1:1.47, as the successful formulation exhibiting drug release pattern very close to theoretical release profile. A decrease in release kinetics of the drug was observed on increasing polymer ratio. The mechanism of drug release from optimized formulation was diffusion coupled with erosion (anomalous).¹⁴

 

v      Deepika V et al., formulated the sustained release matrix tablets of an anti retroviral drug, zidovudine. In this the sustained release matrix tablets were prepared by wet granulation method by using hydrophilic polymers like HPMC, SCMC and Na Alginate. The optimized formulation was further modified using different hydrophobic polymers as granulating agents, such as PVP, Eudragit RL100 and Ethyl cellulose to control the drug release. They found that the hydrophilic matrix of HPMC alone could not control the antiretroviral drug release effectively for 12 hours. Kinetic treatment to the in vitro release data revealed that the drug release followed first order release and mechanism of drug release is by Non-fickian transport.¹⁵

v      Mohd Abdul Hadi et al., prepared zidovudine controlled release beads by ionotropic gelation method, using sodium alginate containing KHCO₃ as the gas-forming agent. The kinetic studies revealed that the drug was released by zero-order kinetics. It was concluded that the floating beads designed for the gastro retentive dosage form could be suitable for controlled drug delivery.¹⁶

 

v      Kar RK et al., formulated and evaluated oral controlled release matrix tablets of zidovudine by direct compression method using various proportion of hydrophilic polymer along or in combination with hydrophobic polymer. Dissolution study revealed that either Eudragit RS100 or RL100 10%, 20% w/w of tablet preparations were able to sustain the drug release up to 9 hours, but 30%, 40% as well as EC combination with 20%  and 25% w/w of Eudragit RS100 and RL100 were able to sustaining the drug release for 12 hour.¹⁷

 

v      Punna  RR et al., designed lamivudine (LMV) oral controlled release matrix tablets using Hydroxypropyl methylcellulose as a retardant polymer and showed good extension release of LMV and overcome the disadvantages of conventional tablets of LMV.¹⁸

 

v      Evelyn O et al., investigated the effect of ethyl cellulose and 6 types of HPMC (Methocel K100M, K100MPRCR, K15MPRCR, K4MCR) on release profile of theophylline from matrix tablets was evaluated. Tablets were prepared either by wet granulation method or direct compression technique. Drug dissolution tests showed that formulations with 15% of Methocel   K4MPR, 15% of Methocel K4MPRCR and 30% of Ethocel N10STD, obtained by direct compression method, compiled with official specifications, in terms of release profile and diffusion was the main mechanism involved in theophylline delivery.¹⁹

v      Vueba  ML et al., studied of different ketoprofen: excipients formulations, in order to determine the effect of the polymer substitution and type of diluents on the drug-release mechanism. The analysis of the release profiles in the light of distinct kinetic models led to the conclusion that the type of polymer did not influence the release mechanism of the drug. Moreover, the drug-release process was found to be slightly influenced by the type of diluents.²⁰

 

v      Harris  SM et al. , developed a once-daily sustained release matrix tablet of ibuprofen using HPMC by directly compression. Different dissolution models were applied to drug release data in order to evaluate release mechanisms and kinetics. The drug release data fit well to the Higuchi expression. Drug release mechanism was found as a complex mixture of diffusion, swelling and erosion.²¹

 

v     Jagan Mohan S et al., formulated controlled release matrix tablets containing 200 mg of levodopa (LD) and 50 mg of carbidopa (CD). The tablets were prepared by direct compression. From the in-vitro release studies of the prepared formulations, one formula was optimized from each polymer.  HPMC K15M and CP 974P based tablet formulations showed high release retarding efficiency. Matrix tablets produced with CP 974P showed sticking and weight variation problems. All the formulations showed linear release profiles (r =0.96) and sustained the release of levodopa and carbidopa over 8–12hrs.²²

 

Punna Rao et al ^{32 33} prepared the controlled release (CR) matrix tablets of zidovudine (AZT) using HPMC, ethyl cellulose EC and carbopol-971P CP.

 

 Kuksal A³⁴, prepared the matrix tablets of zidovudine using hydrophilic Eudragit RLPO and RSPO alone or their combination with hydrophobic ethyl cellulose. Zidovudine microcapsules prepared with _PLGA 35-36_.

Ø      Reddy et al.^[7] have prepared the sustained-release matrix tablets of nicorandil by the wet granulation method by using granulating agents viz – ehtylcellulose, eudragit RL-100, eudragit RS-100, and polyvinylpyrrolidone along with hydroxypropyl methylcellulose, sodium carboxy methylcellulose.

 

Ø      Wu et al.^[8] have optimized the formulation and evaluation of  the extended-release tablets of propranolol by using HPMC and MCC as a polymers.

 

Ø      Mura et al.^[9] have prepared the influence of formulation and process variables on in vitro release of theophylline of matrix tablets by direct compression of drug and different pH-dependent (Eudragit  L100, S100, L100-50) and pH-independent (Eudragit RLPO and RSPO) polymer combination.

 

Ø      Hayashi et al.^[10] have compared the formulation study and drug release mechanism of a new theophylline sustained-release preparation by two matrix tablets with different release mechanisms.

 

Ø      Hayashi et al.^[11] have studied the in vitro and in vivo sustained-release characteristics of theophylline matrix tablets and novel cluster tablets.

 

Ø      Mura et al.^[12] have prepared the sustained-release matrix tablets of metformin hydrochloride in combination with triacetyl-b-cyclodextrin, by direct compression method.

 

Ø      Tadros et al.^[13] have studied the design and in vitro/in vivo evaluation of novel nicorandil extended release matrix tablets based on hydrophilic interpolymer complexes and a hydrophobic waxy polymer.

Ø      Kojima et al.^[14] have prepared the extended release of a large amount of highly water-soluble diltiazem hydrochloride by utilizing counter polymer in polyethylene oxides and polyethylene glycol  matrix tablets.

 

Ø      Reppas et al.^[15] have compared the different release apparatus in generating in vitro–in vivo correlations for extended release formulations.

 

Ø      Garbacz et al.^[16] have compared the dissolution profiles obtained from nifedipine extended release formulation using different dissolution test apparatuses.

 

Ø      Hoag et al.^[17] have studied the sustained release dosage forms and dissolution behavior prediction of matrix tablets using NIR spectroscopy.

 

Ø      Khan et al.^[18] have studied the formulation and evaluation of sustained release matrix tablets of propranolol hydrochloride using sodium carboxymethyl guar as rate sustaining polymer.

 

Ø      Keny et al.^[19] have prepared the  formulation and evaluation of minocycline hydrochloride extended release matrix tablets, by wet granulation technique.

 

Ø      Morkhade et al.^[20] have prepared the  gum copal and gum damar : novel matrix forming materials for sustained drug delivery,by wet granulation technique using isopropyl alcohol as a granulating agent.

 

Ø      Tajiri et al.^[21] have studied the dosage form design and in vitro/in vivo evaluation of cevimeline extended-release tablets, by two types simple matrix tablets and press-coated tablets (hydroxypropylcellulose).

Ø      Mourao et al.^[22] have studied the dissolution parameters for sodium diclofenac-containing hypromellose matrix tablets, by the wet granulation technique (HPMC, magnesium stearate, PVP, MCC, and lactse).

 

Ø      Moghal et al.^[23] have studied the development and optimization of sustained release matrix tablet of ambroxol hydrochloride using central composite design, by direct compression technique using methocel K15M CR as matrix former.

 

Ø      Hiremath et al.^[24] have formulated and evaluated sustained-release matrix tablets of metoprolol tartrate by direct compression technique using HPMC and carbopol-940 as a polymers.