Effect of lyophilization on the characteristics and stability of melanin loaded liposomes

The present study was directed to optimize the stability of melanin liposomes utilizing the technique of lyophilization. Two types of cryoprotectants; sucrose and lactose, each in two concentrations of 5% and 10% were used. Lyophilized liposomes [10% lactose] either fresh or stored for one year at 5°C showed no significant changes [P>0.05] in the phase transition temperatures [Tc], structure and shape, and size distribution of the fresh unlyophilized liposomes. The fresh unlyophilized liposomes were unilamellar with Tc of 41.6°C and an average size of 5.21 micro m. The stored unlyophilized liposomes showed a significant [P<0.05] decrease in Tc [32.8°C] and increase in the average size [15.6 micro m] with the formation of onion- like multilamellar vesicles compared with the fresh unlyophilized ones. Lyophilization of melanin liposomes with different cryoprotectants significantly [P<0.001] decreased the rate of leakage of entrapped melanin from the liposomal structure compared with the unlyophilized ones. This cryoprotection effect was significantly [P<0.05] increased by the use of lactose and by increasing the cryoprotectant concentration. The entrapped melanin in lyophilized liposomes with 10% lactose was chemically stable for six months at 5°C as evaluated by mass spectroscopic analysis. As a conclusion, lyophilization with 10% lactose maintained the chemical stability of melanin and significantly improved the physical stability of melanin liposomes

Formulation and stability of ciprofloxacin hydrochloride ophthalmic eye drops

Ciprofloxacin hydrochloride [CPX-HCL] ophthalmic solutions were formulated using different, polymers, buffers and antioxidants. The polymer solutions tested were sodium carboxy methylcellulose [SCMC] 0.1%, hydroxypropyl methylcellulose [HPMC] 2%, methylcellulose 400 [MC] 0.6%, polyethylene glycol 6000 [PEG] 10%, polyvinyl alcohol [PVA] 2% and polyvinylpyrrolidone K25 [PVP] 10%. [CPX-HCL] gave clear solutions with only [MC] and [HPMC] at the same pH range of other tested polymers. Also, the acetate buffer [pH 4.8] was the only suitable buffer for forming a stable ophthalmic solution. The results also revealed that 0.05% is the optimum EDTA concentration as antioxidant. Consequently, the eye drops were prepared with 0.6% MC and 2% HPMC in distilled water or in presence of acetate buffer [pH 4.8]. Benzalkonium chloride [0.004%] was added in all formulae and the isotonicity was adjusted by sodium chloride. The stability of the four formulae was investigated for 24 months at different temperatures [4C, 37C and 45C]. The drug showed greater stability in acetate buffer than in double distilled water. The formula prepared with HPMC in acetate buffer exhibited the highest stability at all tested temperatures. This formula showed reduction in drug potency by 94.69, 91.09 and 86.01% after storage for two years at 4C, 37C and 45C, respectively. All formulae showed reduction in drug potency to about 85% of its initial potency after storage for 14 days in presence of light at room temperature. The low density high density polyethylene plastic containers and amber colored glass showed insignificant difference on drug stability

Effect of aging on the physico-chemical stability of acetazolamide and phylpropanolamine hydrochloride tablets

The effect of ageing on the physicochemical stability of acetazolamide and phenylpropanolamine HCl tablets, directly compressed with Dynasan 114 and 118, was studied. Three temperature levels [25, 40 and 60C] at 75% relative humidity were adopted, either in closed or open containers over a 6-month storage period. The results revealed that the tablets stored in closed containers did not exhibit any significant changes in properties. However, tablets containing Dynasan 114 and stored at 60C were completely deformed after 4 months. All tablets stored at 75% relative humidity showed a significant increase in their weights and decrease in hardness values. The disintegration time and dissolution profiles [t 50%] of acetazolamide tablets containing Dynasan 114 or 118 were not affected by phenylpropanolamine HCl tablets, containing Dynasan 114 or 118, caused a decrease in their disintegration times and t 50%. The drug content and uniformity of weight of both drug content and uniformity of weight of both tablets were not affected in all formulations under the tested storage conditions

Stability of thiamine hydrochloride in liquid formulations

The stability of thiamine hydrochloride in aqueous media at 25, 37 and 60C, for 6 months was studied. In pure distilled water, thiamine hydrochloride was found to be stable for 6 months at 25C, while at elevated temperature, the residual% values were 85.0 and 66.2% at 37 and 60C, respectively. In the presence of light, appreciable loss of potency was observed in less than 3 months. The effect of McIlvain and phosphate buffers at different pH values have been also investigated. Maximum stability was found at pH 4 to 4.5 McIlvain buffer at 25 and 37C. On the other hand, the effect of certain additives commonly used for formulation of antidiarrheal containing thiamine hydrochloride, demonstrated that, at either 37 or 60C Aerosil 200 and bismuth oxycarbonate did not cause any significant decrease in potency. In contrast, veegum reduced the potency to 25.5 and 15.0% at 37 and 60C, respectively, after 3 months. At 37C, thiamine hydrochloride was stable for one month in presence of kaolin, while at 60C a significant decrease in its potency was found. In presence of mixture of vitamins B, ferric ammonium citrate, calcium pantothenate and calcium gluconate, the rate of decomposition of thiamine hydrochloride was highly accelerated