Formulation Of Floating Microspheres Of Clarithromycin Biology Essay

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100μg/ml of clarithromycin is prepared and scanned from the wavelength of 200 to 800 nm in UV spectroscopy. The peak with the highest absorbance was taken as the lambda max of rifampicin for further studies.

The technique of floating microspheres preparation is based on emulsification solvent evaporation method in which the polymer ethylcellulose was dissolved in 50ml of acetone at different concentrations with stirring. Carbopol 934P, calcium carbonate and clarithromycin of different concentrations were added to the above polymer solution and the total mixture was blended for 2h (Siddalingam Rajinikanth et al., 2008). Then this suspension was slowly added to the 200ml light liquid paraffin which containing 2.0% Span 80 and stirred at a rate of 1200 rpm using Remi mechanical stirrer equipped with a three bladed propeller at room temperature for 1h (Patel et al., 2006). After 1h of emulsification, acetone was evaporated gradually with the help of a rotary flask evaporator at 400C until the microspheres were formed. The formed microspheres were washed with petroleum ether (400 - 600 C) and dried at room temperature. Fourteen formulations had been prepared by this method; the various parameters considered for optimisation were shown in the table no 1.

Table No1: Formulation optimisation of floating microspheres of clarithromycin

Formulation Code

Ethylcellulose %

Calcium carbonate %

Carbopol %

Clarithromycin %

F1

2.5

1.5

1

2.5

F2

2.5

2

1

2.5

F3

2.5

2.5

1

2.5

F4

2.5

3

1

2.5

F5

1.5

2

1

2.5

F6

2

2

1

2.5

F7

3

2

1

2.5

F8

2.5

2

0.5

2.5

F9

2.5

2

2

2.5

F10

2.5

2

3

2.5

F11

1

-

-

1

F12

0.5

-

-

1

F13

2

-

-

1

F14

3

-

-

1

Morphological characterization:

Determination of particle size:

The particle size of the prepared microspheres was determined by the Phase Contrast Microscopy. The samples were dispersed in the liquid paraffin and the sizes of microspheres were observed under microscope.

Standard graph of Clarithromycin:

Accurately 100 mg of clarithromycin were weighed and dissolved in 100 ml of pH 2 (0.1 N Hcl) buffer (stock solution). The required concentrations i.e., 100μg/ml, 200μg/ml, 300μg/ml, 400μg/ml, 500μg/ml and 600μg/ml were prepared by pipetting out 1ml, 2ml, 3ml, 4ml, 5ml and 6ml of stock solution respectively and the volume is made up to 100 ml with pH 2 buffer. The absorbance was determined through UV spectroscopy at 210 nm. A graph is plotted by taking concentration of the solution in X axis and absorbance in Y axis (C. Vijaya Raghavan et al., 2005).

FT-IR Spectroscopy:

The pure drug, polymer and formulation was mixed with IR grade potassium bromide in a ratio of (1:100) and pellets were prepared by applying 10 metric ton of pressure in hydraulic press. The pellets were then scanned over range of 4000-400cm-1 in FTIR instrument.

Determination of entrapment efficiency:

Accurately 50 mg grounded powder of microspheres were soaked in 50 ml of distilled water and sonicated using probe sonicator for 2 h. The solution was centrifuged and the entrapment efficiency of the drug was determined by measuring the concentration of free drug present in the supernatant (Venkateswaramurthy et al., 2010) after centrifugation at 13,000 RPM for 30 min at 40C. The concentration of drug present in the supernatant was determined through UV spectrophotometer (Shimadzu 1650, Japan) at 210nm. The following formula determines the percentage drug entrapment:

In Vitro Buoyancy Studies:

The floating microspheres about 100 mg were spread over the surface of the dissolution medium of 900ml simulated gastric fluid (SGF, pH 2.0), which is placed in USP dissolution apparatus II. The medium temperature was maintained at 37 °C and was agitated by paddle at 100 rpm. After agitation the microspheres that floated over the surface of the medium and those that settled down at bottom of the flask were recovered separately and dried (Siddalingam Rajinikanth et al., 2008). The percentage of floating microspheres was determined by following equation:

Buoyancy (%) = (weight of microspheres floated on medium)/

(Weight of microspheres floated in medium+

Weight of microspheres settled at bottom of flask) x 100

Stability studies:

The physical and chemical stability of clarithromycin loaded floating microspheres were evaluated by storing the formulations at humidity controlled oven (400C), room temperature (280C), and at refrigeration temperature (2-80C). Samples were withdrawn at fifteen days time interval for 60 days and were checked for appearance, entrapment efficiency and buoyancy percentage.

In vitro drug release studies:

The in-vitro dissolution studies were carried out by using USP II paddle type dissolution apparatus. Accurately 100mg of clarithromycin floating microspheres was introduced into 900 ml of pH 2 (0.1 N Hcl), used as a dissolution medium, maintained at a temperature of 37°C, and a rotation speed of 100 rpm (Shashikant D. Barhate1 et al., 2005). The samples of 5ml were withdrawn at predetermined time intervals of every one hour for twelve hours. The samples were analyzed spectrophotometrically at 210 nm to determine the percentage of drug release.