The development of controlled drug delivery system for the treatment of chronic disease is of great interest since this system act as a vector carrying the drug not only to the target but also adverse effect can be reduced. In the recent past, carbohydrate and biodegradable polymers have been extensively used to develop the controlled release formulation. Over the past decades, blends have been investigated to satisfy the need of specific sectors of polymer industry. Such polymer blend show superior performances over the conventional individual polymers and consequently, the range of application have grown rapidly for such class of materials.

Novel drug delivery system

Today a pharmaceutical scientist is well worsed with the fact that the overall action of the drug molecule is not merely dependent on its inherent therapeutic activity, rather on the efficiency of its delivery of the site of action. An increasing appreciation of the later has led to the evolution and development of several drug delivery systems (DDS) aimed at performance of the enhancement of the potential drug molecules. A review of the literature has revealed the recent several technical advancement have led to the development of various Novel Drug Delivery System(NDDS) that could revolutionize method of drug delivery and hence could provide definite therapeutic benefits. The new way of patenting the drug is to use “Novel Drug Delivery System”1 i.e. NDDS with improved bioavailability (BA). To formulate or to re formulate it in a form of NDDS is not a Herculean task if one goes methodically and skillfully this is where the formulation development study plays an important role.

Controlled drug delivery system

For most of civilized history, there was no clear difference in the way in which humans consumed food and medicine. To date, oral delivery is still the preferred route of drug administration, especially for chronic therapies where repeated administration is required. Oral administration offers patients less pain, greater convenience, higher likelihood of compliance, and reduced risk of cross-infection and needle stick injuries. physiological parameter inherent in a selected route of administration.

1. Reduction in fluctuation of drug blood levels about the mean.
2. Reduce the dosage frequency.
3. To improve patients compliance.
4. To ensure safety and improve efficacy of drugs.

MATERIALS AND METHODS

Analytical methods for the estimation of glimepiride

1. Determination of ? max for glimepiride71,72

Stock solution:

Glimepiride in pH 6.8 buffer solution (10 mg in 10 ml methanol)

Scanning:

From the stock solution 10µg/ml solution of glimepiride prepared in pH 6.8 buffer solution and scanned   between 200-400 nm. The absorption maxima of 228 nm was selected and used for further studies.

2. Preparation of standard calibration curve of glimepiride

The standard calibration curve for glimepiride was prepared using pH 6.8 phosphate buffer.

Standard solution

10 mg of glimepiride was dissolved in 100 ml methanol to give a concentration of 1 mg/ml.

Stock solution                         

From standard solution take 10 ml of solution in 100 ml of phosphate buffer of pH 6.8 to produce the 100 mcg/ml concentration and take from the 100 mcg/ml of the solution aliquots of 0.2,0. 4, 0.6, 0.8, 1.2, 1.6 and 2.0 ml of stock solution was pipette out in 10ml volumetric flask. The volume was made up to mark with buffer of pH 6.8  to produce concentration as 2, 4, 6, 8, 12, 16 and 20 mcg/ml of glimepiride respectively. The absorbance of prepared solution of glimepiride was measured at 228 nm in Shimadzu UV/visible 1700 spectrophotometer against phosphate buffer pH 6.8 as blank. The absorbance data for standard calibration curve are given in table no-1 and plotted graphically as shown in the Fig - 2. The standard calibration curve yields a straight line, which shows that drug obeys Beer’s law in the concentration range of 1 to 20 mcg/ml.

Method of preparation of blank polymer blends73

The blank polymer blendes were prepared using different concentration of agar, isabgol, aloevera and gelatin by solvent casting technique, the detailed composition is given in Table-2.

Solvent casting method

Accurately weighed quantity of agar was dissolved in distilled water. The solution was slowly heated to around 70oC to form a gel like consistency. Stirring was done in order to avoid bubbles in the final gel solutions. After stirring for about one hour, the optically clear solutions were obtained. The resultant solutions were poured into an upright placed glass syringe with a top cut off (machined perpendicularly to the cylinder axis), which was kept in an oven at 60 ?C before use. The warm polymer solutions in the syringe were allowed to equilibrate at the ambient temperature (about 25 ?C) to form a gel. After drying, solidified gel was cut in to 1 ml size. Similarly, isabgol, aloevera and gelatin polymer blends were also prepared by solvent casting technique at their gelation temperature 40, 60 and 90oC respectivel

       
           
       
    Table 1: Formulation details of blank polymer blends

       
           
       
    Table 2: Formulation details of drug incorporated polymer blends

Each 1 ml thick ring contains 4 mg of glimepiride.

RESULT AND DISCUSSION

       
           
       
   Figure 1: U.V scanning photograph of glimepiride

       
           
       
    Table 3: Standard calibration curve data of glimepiride in phosphate buffer pH 6.8

       
           
       
    Figure 2: Standard calibration curve data of glimepiride in phosphate buffer pH 6.8

       
           
       
    Figure 3:  Photograph of the glimepiride polymer blend preparations containing (a) agar - aloevera PB1 (b) agar - gelatin PB3 (c) aloevera - gelatin PB9    (d)  gelatin - isabgol PB11.

       
           
       
    Figure 4: FTIR spectra of drug and polymer

Figure 8: Scanning electron micrograph of glimepiride loaded polymeric blend containing agar + aloevera (PB2)

       
           
       
    Table 4 : Evaluation parameter of glimepiride polymer blend (mean I.S.D, n=3)

       
           
       
    Figure 9: Photograph of In vitro swellable polymeric blend (a) agar - aloevera PB1 (b) agar - gelatin PB3 (c) gelatine - isabgol PB11 after 3 hour and 6 hour

In vitro swelling data of glimepiride polymeric blend containing   agar - aloevera (2:1) PB1, agar aloevera (3:1) PB2, agar - gelatin (1:1) PB3, agar - gelatin (3:1) PB4 Percent swelling index of PB1 to PB4 Figure 10: