Useful for calculation of biopharmaceutics and pharmacokinetics data in laboratory.

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BIOAVAILABILITY = BIO (IN BLOOD) + AVAILABILITY (AMOUNT/EXTENT OF DRUG IN
BLOOD)
Bioavailability is defined as the EXTENT (AMOUNT) and the RATE (MAY BE
FIRST ORDER OR ZERO ORDER) at which the ACTIVE INGREDIENT
(unchanged form of drug or active molecules) is delivered To The Systemic
Circulation (IN PLASMA/BLOOD)from the dosage form(or from absorption site).
HOW
?
WHY ?

3. FOR CALCULATION OF BIOAVAILABILITY WE USED PHARMACOKINETICS
AND PHARMACODYNAMICS METHOD .

4. For calculation of bioavailability we take blood sample and
evaluate the concentration of drug in blood plasma.
(EXTENT/AMOUNT OF TOTAL DRUG IN BLOOD)
FOR THIS WE USED TRAPEZOID RULE.
BLOOD PLASMA METHOD
Area of Trapezoid = a
(b+c/2)
WHAT IS
TRAPEZOID?
b c
a
TRAPEZOID

5. S.N
O.
TIME
(IN
MIN)
PLASMA
DRUG
CONCENTRAT
ION (MG/ML)
0 0 t0
0
C0
1
t1
C1
2
t2
C2
3
t3
C3
4
Plot the graph between plasma drug concentration and time.
Cmax
Tmax

6. METHOD
1.Plot the graph between plasma drug concentration vs. time.
2.For calculation of bioavailability calculate the AUC(area under the
curve).
3.For AUC calculation break the total graph into small trapezoid area
and calculate the area of trapezoid.
For example :- according to above figure the AUC of single trapezoid
is Area of Trapezoid = a (b+c/2)
where a is time on x axis and b,c is concentration
on y axis.

7. 4. Calculate the total AUC of graph is
5.Now calculate the Area 2, AREA 3, AREA 4, AREA 5 ,AREA 6,AREA 7
AUC OF GRAPH = Area 1+Area 2+Area3+Area 4+Area 5+Area 6+Area 7+ C*/K
(AUC)0
t
(AUC)t
∞
6 Here C*/K = Last observed plasma drug concentration/overall elimination rate constant.

8. K = OVERALL ELIMINATION RATE CONSTANT.
For calculation of K we used i.v.bolus one compartment open model equation. from this
equation
K/2.303 = SLOPE = LOG Y1-LOG Y2 / X2-X1
From this equation we calculate the log value of PDC(Plasma drug concentration) and
plot the graph between Log PDC VS TIME.
Select any two point from the graph and calculate the slope.

9. S.No.
Pharmacokinetic
Factor Name
Result
1
Maximum plasma drug
concentration (Cmax)
Peak of graph
2
Time at Maximum
plasma drug
concentration (tmax)
Time at Cmax
3
(AUC)0
t
4 (AUC)t
∞
The Absolute Bioavailability = AUC (Oral) × Dose (IV)
AUC (IV) × Dose (Oral)
RESULT – From the above study the following data was obtained –

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BHARDWAJ CLASS