| Objective: To explore the effect of the phase transition process of new Mu-an ophthalmic in-situ gel on the Corneal infiltration in vitro and drug transport kinetics in rabbit aqueous humor,and compared with ordinary gel, evaluating the dosage form characteristic of in-situ gel, provide the basis for pharmacy, pharmacodynamics,toxicology and clinical application.Method: Using inclined method to determination the phase transition temperature of temperature-sensitive in-situ gel,the Single factor of influence on in-situ gel phase transition temperature matrix was made on poloxamer407, poloxamer188, according to the temperature sensitive in-situ gel to requirements of phase transition temperature determine the in the range of matrix concentration. Taking phase transition temperature of Simulated tear dilution before and after(T1,T2) as an indicator,through the central composite design and response surface method screening instant type gel matrix proportion, determining the composition of prescription. By high performance liquid chromatography determination of the content of ganciclovir in each gel, methanol-water(5:95) as the mobile phase, using phenomenex C18 column,detection wavelength 252 nm, flow rate 1.0m L/min, and quantitative analysis of the in vivo study methodology. In normal saline, the new Mu-an ophthalmic in-situ gel is used as the test substance, were of ocular irritation test,providing a basis for studies of Corneal infiltration in vitro and drug transport kinetics in rabbit aqueous humor.Using in vitro corneal penetration test, comparative study of new Mu-an ophthalmic in-situ gel and ordinary gel in vitro corneal permeability characteristics, the establishment of drug kinetic equation in vitro corneal penetration,Calculating the time required to reach 50% of corneal permeation amount and the cumulative percentage of corneal penetration.New Zealand rabbits as test subjects using ocular give a new Mu-an ophthalmic gel and normal gel, taken aqueous humor of different time points, determination of the content of ganciclovir, the establishment of drug transporters in the aqueous humor dynamics equations, calculating the transit of drugs in vivo pharmacokinetic parameters(such as the absorption half-life, elimination half-life, peak time, peak concentrations, AUC, etc.). Compare with the difference of durg transport dynamics in the rabbit eye between new Mu-an ophthalmic gel and ordinary gel.Results: The results of single factor experiment show that the concentration of poloxamer407 and poloxamer188 has significant effect on phase transition temperature of temperature sensitive in-situ gel.The greater concentration of P407, the lower phase transition temperature, while the greater concentration of P188, the phase transition temperature is higher. Through the central composite design and response surface method for phase change temperature and the concentration of gel matrix for the fitting equation are as follow(A is P407,B is P188):T1=26-15.25×A-1.87×B-9.05×A×B+4.56×A2-9.09×B2 T2=38.23-20.11×A+5.3×B-13.88×A×B+4.62×A2-8.89×B2 after prescription screening and verification experiments, finally determine the matrix proportion of new Mu-an Ophthalmic in-situ gel is 19.34% P407 and 1.73% P188?The results of preliminary evaluation quality show that every quality evaluation index of new Mu-an the ophthalmic in-situ gel are in accord with a standard pharmacopeia of 2015 edition. Content determination of GCV and methodology results indicate that the concentration of GCV in new Mu-an ophthalmic in-situ gel between the peak area are in good linear relationship when the concentration of GCV in the rang of 0.556?g/m L~55.6 ?g/m L,Y=2.25+29.35C(R2=0.9999,F=339111,P=0.0001)(n=7). The average sample recovery rate is 97.44%, RSD=1.27%<5%, concentration of GCV in new Mu-an ophthalmic in-situ gel is 1.086(mg/g). Stimulating experiments show that this preparation conforms to the ophthalmic drug safety, which has no irritation to rabbit eyes. In vitro corneal permeability test results: the corneal permeability of new Mu-an ophthalmic in-situ gel is in accordance with the negative exponential model,and the regression equation is: Y=0.8543*EXP(-16.678/t).Gel in vitro corneal permeability law consistent with the Weibull function model, the regression equation is: Y=0.7025(1-EXP(-((t+3.3767) /66.99) ^1.145)), in drug isolated cornea permeation rate, in-situ gel t50%=20.59(min) short to ordinary gel(t50%=46.30(min),on the other hand is both drug cumulative release amount compared, i.e. gel type of the ultimate drug cumulative release amount of 80.81% greater than ordinary gel of the ultimate drug cumulative release amount of 70.00%.Experimental results of pharmacokinetics of intraocular drug transport: new Mu-an Ophthalmic gel in aqueous humor to dynamic equations of motion for ganciclovir as follow:C=18.94*EXP(-0.0154t)-18.94*EXP(-0.07985t),ordinary gel in aqueous humor to dynamic equations of motion for ganciclovir as follow:C=15.42*EXP(-0.0153t)-15.42*EXP(-0.0488t).Comparative analysis of new Mu-an Ophthalmic in-situ gel and ordinary gel from different pharmacokinetic parameters can know that reached peak time for new Mu-an Ophthalmic in-situ gel is 25.21 min, peak concentration is10.32 ?g/m L, absorption half-life is 8.679 min and the AUC is 992.4 min* ?g/m L, but reached peak time for Ophthalmic ordinary gel is 34.63 min, peak concentration is 6.232 ?g/m L, absorption half-life is 31.07 min and the AUC is 691.4 min* ?g/m L. The results of in vivo correlation evaluation of new Mu-an ophthalmic in-situ gel and ordinary gel show that the content of ganciclovir in Mu-an ophthalmic in-situ gel have a good correlation between in vitro corneal permeability and transport within the aqueous humor, and the same to ordinary gel. In vitro and in vivo correlation regression equation of Mu-an ophthalmic in-situ gel and ordinary gel as follows: ?a=1.243?r+3.(p=0.0001<0.05),?a=2.325?r-19.69(p=0.0001<0.05).Conclusion: After administration of new Mu-an ophthalmic in-situ gel,Such dosage forms exist phase transitions which can transition from liquid to a semi-solid,causing both the AUC of in vitro corneal penetration and aqueous humor transport in rabbit eyes significantly increased.,thus in-situ gel has maximum ?H, but ordinary gel's ? H = 0, so that the permeation mechanism of in-situ gel is different from ordinary gel. The speed of in vitro corneal penetration of new Mu-an ophthalmic in-situ gel faster than normal gel,is 2.249 times of normal gel, and total vitro corneal penetration more than ordinary gels, Cumulative permeation percentage was 1.154 times than ordinary gel.Aqueous humor transport kinetics model in rabbit eyes of in-situ gel differs from ordinary gel, indicating that the mechanism of transport in rabbit eyes within in-situ gel is different from the normal gel.The peak time of the in-situ gel faster than normal gel, tmax is 1.37 times of the normal gel, peak concentration of in-situ gel is higher than normal gel, Cmax is 1.66 times of the normal gel, AUC of in-situ gel is greater than normal gel, Cmax is 1.44 times of the normal gel,absorption half-life of in-situ gel is shorter than normal gel, t(1/2)ka is 1.64 times of the normal gel, and elimination half-life is equivalent with ordinary gel. The results of study show that in-situ gel not only shortens the onset time of durg but also increases the bioavailability of the drug compared with ordinary.This feature may be due to its unique phase-change machine mechanism(from a liquid into a semi-solid), it transformed the phase-change potential into the energy promoting corneal penetration of kinetic, thereby increasing the total amount of drugs into the cornea, shortened the drug onset time.To infer that in-situ gel can maximize efficacy and reach the requirements of clinical drug application. |
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