. . . Guided by Dr B D Rohera

:- Presented by Paavan Trivedi

1

Con

cent

ratio

n (m

cg/m

l)

Time (hours)

50 ° C 60 ° C 70 ° C 80 ° C

Time (Hr)Conc.

(mcg/ml)Time (Hr)

Conc.(mcg/ml)

Time (Hr)

Conc.(mcg/ml)

Time (Hr)

Conc. (mcg/ml)

0 100 0 100 0 100 0 100

1.2 99.75 0.75 97 0.7 94 0.5 91

2.7 99.65 1.8 93 1.5 88 0.8 85

4.2 98.45 3 89 2.3 81 1.4 78

5.6 98.45 4 86 3.45 75 2 71

6.9 97.25 4.8 83 4 73 2.4 67

8.1 95.75 6.5 78 5 67 3.5 56

10.8 93.65 9.3 74 6.5 62 4.5 50

Temperature(˚C)

R2 K 0

(min -1)T1/2

(hr)T10%

(hr)

50 0.917

0.5859

85.34 17

60 0.972

2.88815

17.31 3.46

70 0.974

5.89786

8.48 1.7

80 0.971

10.9716

4.56 0.91

50° C 60° C 70 ° C 80 ° C

Time (Hr) ln Conc. Time (Hr) ln Conc. Time (Hr) ln Conc. Time (Hr) ln Conc.

0 4.607 0 4.6 0 4.6 0 4.6

1.2 4.605 0.75 4.57 0.7 4.56 0.5 4.54

2.7 4.601 1.8 4.55 1.5 4.49 1.3 4.36

4.2 4.59 3 4.51 2.25 4.42 2 4.3

5.6 4.59 4 4.48 3.45 4.33 2.4 4.2

6.9 4.58 4.8 4.44 4 4.3 3.5 4

9.3 4.56 5.6 4.42 5 4.2 4 3.93

10.8 4.55 7.5 4.37 6.5 4.07 4.5 3.85

Temperature R2 K 1( min -1) K 1( min -1)Reported

T1/2( )hr T10% ( )hr

50 0.9525 0.0001 0.0002 129 19.37

60 0.994 0.00052 0.0006 22 3.33

70 0.998 0.0013 0.0013 8.47 1.27

80 0.996 0.0028 0.0024 4.1 0.61

Temperature T( )kelvin

1/T 1/ ×10T 3 Rate constant

( )K calculated Rate

constant×10k 6

ln K

50 323 0.00309 3.09 0.0001 100 4.605

60 333 0.003 3 0.00052 520 6.253

70 343 0.00291 2.91 0.0013 1300 7.17

80 353 0.00283 2.83 0.0028 2800 7.937

Slope= -Ea/REa = 12.582 x 1.987Ea = 25.004 Kcal/mole

K at 25 ̊ C = 4.48 x 10-6 min -1

T10% value calculated from Arrhenius plot: T10% = 0.104/4.48 x 10-6

= 23214 min = 387 Hr

Temperatu re

( )˚C

Frequency ( )Factor A

Entropy ofActivation

(Δ )S/ Cal moledeg

50 0.0052 37.91

60 0.03 29.63

70 0.079 22.10

80 0.164 16.15

Temperature( )˚ K T10% ( )min Ln T10% 1/T 1000/T

323 1162.2 7.06 0.0031 3.096

333 199.8 5.3 0.003 3

343 76.2 4.33 0.00291 2.92

353 36.81 3.61 0.0028 2.83

Plot T10% ( )Hr

Free & Blythe

386

Arrhenius

387

At 100 % of labeled amount the Shelf life is 16 Days.

At 110% of labeled amount the Shelf life is increased to 32 Days.

To obtain Shelf life of 48 days the required amount is 120 %

From careful extrapolation of research data, and plotting of Conc. Vs. time did not give straight line.

Plot of Logarithmic forms of Conc. Vs. time showed linearity at all four temperatures.

Thus it can be inferred that the drug follows first order kinetics of degradation.

Further Arrhenius plot and Free and Blythe plot provided information regarding shelf life and possible overages that. can be added in an attempt to increase shelf life.

Addition of 10% overages increases the shelf life of product from 16 to 32 days, almost double the initial value.