Formulation and evaluation of a buccoadhesive captopril tablets

Buccoadhesive tablets of captopril were prepared by direct compression of the drug with different polymers; Carbopol 934 [CP 934], EudragitRS 100 [EU RS 100], Chitosan [Ch], Hydroxpropyl methylcellulose [HPMC] and Polyvinylpyrrolidone K[30] [PVP K[30]] either singly or in blends of different ratios. The tablets were evaluated for their weight variation, drug content uniformity, friability, hardness, swelling index, surface pH, in-vitro bioadhesive strength and release characteristics. The bioavailability and the pharmacokinetics parameters of captopril from two selected formulations [CP 934:HPMC 6:4 andCh:HPMC 6:4] were evaluated. The in-vitro bioadhesive strength and release characteristics were found to be a function of the type of polymer and ratio of polymer blends. Swelling and bioadhesive characteristics were determined for both plain and medicated tablets. The high concentration of carbopol and chitosan containing formulations showed the greatest adhesive strength. The mean pharmacokinetic parameters of captopril after buccoadhesive tablet administration were: C[max] 506.9 ng/ml, T[max] 4 hr, AUC[0-8] 2359.5 ng.hr/mlfor CP 934: HPMC [6:4], while C[max] 429.02 ng/ml, T[max] 2.67 hr, AUC[0-8] 1637.43 ng.hr/ml for Chitosan: HPMC [6:4]. In comparison, in case of oral administration of control tablet the C[max] 591.28 ng/ml, T[max] 1.5 hr, AUC[0-8] 1869.29ng.hr/ml

Bioavailability and ocular disposition of ketorolac tromethamine from various ophthalmic preparations

Ketorolac tromethamine was formulated in different ophthalmic preparations namely; eye drops, gels, ocuserts and ointments using the following carriers; sodium carboxymethyl cellulose [sod. CMC], polyvinyl alcohol [PVA], hydroxypropylmethyl cellulose [HPMC], absorption base and gelatin. The ophthalmic formulations were prepared containing 0.5% of the drug. All prepared formulae containing the drug were subjected to stability study and release characteristics. Also, the effect of these drug carriers on the uptake and ocular disposition of ketorolac tromethamine by the eye tissues of rabbits [conjunctiva, cornea, iris-ciliary body and aqueous humor] was studied. The obtained results revealed that, the released amounts from the ophthalmic preparations after six hours can be arranged in the following order; Eye drops > ocuserts > gel > ointments. Sod CMC eye drops exhibited the higher rate of release than sod CMC gel, PVA and absorption base ointments. Gelatin ocuserts exhibited the higher rate of release than HPMC ocuserts and carbopol 934 and sod CMC ocuserts. The release rate of the drug from eye drops and PVA ointment obeys first order kinetics, while, other preparations obey Higuchi diffusion model with non-Fickian kinetics. Most formulations [including eye drops] could be stored for 6 months at 25°C, 35°C, 45°C without physical or chemical degradations of the drug. However, PVA and absorption bases showed some changes in the drug content [t[90] was 2.84 months for both at 45°C]. The decomposition rate ofketorolac tromethamine followed the first-order degradation kinetic. The highest stable formulae are, sod CMC eye drops and gel [t[90] values were, 151.9 and 91,18 months, respectively at 45°C]. The highest concentration of the drug [Cmax] from all tested formulations is provided in conjunctiva followed by cornea, iris-ciliary body, then aqueous humor. The peak time for maximum drug concentration [Tmax] from sod CMC eye drops was two hours. While, that for sod CMC gel, PVA ointment and gelatin ocuserts was three hours in all tissues after the application of the tested formulations. In addition, the total availability of the drug from the tested formulations was in the following order: gelatin ocuserts > sod CMC gel > PVA ointment > sod. CMC eye drops

Formulation and stability study of naproxen ophthalmic preparations

Naproxen was formulated in different ophthalmic preparations as drops, gels and ocuserts using cellulose derivatives such as methylcellulose, sodium carboxymethylcel-lulose and hydroxypropyl methylcellulose. All the prepared formulae [drops, gels and ocuserts] containing the drug were subjected to the study of the release characteristics. Also, the stability of naproxen ophthalmic preparations at different conditions of storage were investigated. The obtained results revealed that, the percentage released of naproxen from the three ophthalmic dosage forms after 7 hours were found to be in the following order; Drops>ocuserts>gels. These formulations exhibited the highest physical and chemical stability up to 6 months of storage at 25°C, 35°C and 45°C, except the formulae containing methylcellulose polymer, showed the least stable formulations. The drug content in the formulae containing methylcellulose was decreased about 10% after storage at different temperatures for 6 months

In-vitro evaluation of enrofloxacin ophthalmic preparation containing cyclodextrins

The effects of cyclodextrins [CyDs] [hydroxy propyl beta-cyclodextrin [HP-beta-CyD] and beta-cyclodextrin [beta-CyD]] on the solubility and release characteristics of enrofloxacin [Enr] from ophthalmic ointments and gels were investigated. The ophthalmic gels [sodium carboxymethyl cellulose [sod. CMC] and sodium alginate] and ointments [emulsion, absorption and water soluble bases] were prepared using 0.5% of the drug or equivalent amounts of its complexes with HP-beta-CyD or beta-CyD. The results revealed that the aqueous solubility of enrofloxacin was significantly increased by the formation of [1:2] inclusion complexes with CyDs. However, the solubility of enrofloxacin increased linearly as a function of HP-beta-CyD, followed by beta-CyD