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Pharmacokinetics Bioavailability Guide

This document provides the solved problem and solution for calculating the absolute and relative bioavailability of penicillin and pentoxyifylline from different drug formulations based on AUC values. For penicillin, the absolute bioavailability was calculated to be 64% for an oral tablet compared to IV administration, and 95% for the tablet relative to a suspension. For pentoxyifylline, the absolute bioavailability was calculated to range from 34.6% to 49% for different oral solid formulations compared to IV, and the relative bioavailability of a capsule was 89.5% compared to an oral solution. The capsule formulation showed a higher bioavailability than a sustained release tablet.

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3K views2 pages

Pharmacokinetics Bioavailability Guide

This document provides the solved problem and solution for calculating the absolute and relative bioavailability of penicillin and pentoxyifylline from different drug formulations based on AUC values. For penicillin, the absolute bioavailability was calculated to be 64% for an oral tablet compared to IV administration, and 95% for the tablet relative to a suspension. For pentoxyifylline, the absolute bioavailability was calculated to range from 34.6% to 49% for different oral solid formulations compared to IV, and the relative bioavailability of a capsule was 89.5% compared to an oral solution. The capsule formulation showed a higher bioavailability than a sustained release tablet.

Uploaded by

abdullah2020
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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G.S.N. Koteswara Rao, M.Pharm., D.D.D., D.C.T., (Ph.

D), (MBA)
Asst. Professor,
RAGHU College of Pharmacy,
Visakhapatnam.
www.raghupharmacy.com

Pharmacokinetics Solved Problems


www.pharmainfo.net/og/rcp/downloads

Pharmacokinetics
Bioavailability

Solved Problems
by

G.S.N.K.Rao {Eswar}

PROBLEM-7:
AUC values of penicillin up on i.v administration of 50 mg and oral administration of 100 mg tablet
were found to be 70 and 90 respectively.
Calculate:
a. Absolute Bioavailability of penicillin.
b. Relatively Bioavailability of penicillin from tablet based on penicillin suspension whose dose is
100 mg and AUC is 95.
SOLUTION-7:
a. Calculate Absolute Bioavailability of penicillin.
Given,
i.v. dose of penicillin, Div = 50 mg
Oral dose of penicillin tablet, Doral = 100 mg
AUC of iv administered penicillin, [AUC]iv = 70 mg. hr/lt
AUC of oral administered penicillin, [AUC]oral = 90 mg. hr/lt
Absolute Bioavailability, F = ?
Formula:
[AUC]oral D i.v
Absolute Bioavailab ility, F =
x 100
[AUC]i.v D oral
90 x 50
4500
F=
=
= 0.64 x 100 = 64%
70 x 100
7000
b. Calculate Relatively Bioavailability of penicillin from tablet based on penicillin suspension
whose dose is 100 mg and AUC is 95.
Dose of penicillin tablet, Dtest = 100 mg
Dose of penicillin suspension, Dstd = 100 mg
AUC of penicillin tablet, [AUC]test = 90 mg. hr/lt
AUC of penicillin suspension, [AUC]std = 95 mg. hr/lt
Relative Bioavailability, Fr = ?
Formula:
[AUC]test D std
Absolute Bioavailab ility, Fr =
x 100
[AUC]std D test
90 x 100
9000
Fr =
=
= 0.95 x 100 = 95%
95 x 100
9500
www.pharmainfo.net/eswar

Page 1 of 2

eswar@pharmainfo.net

G.S.N. Koteswara Rao, M.Pharm., D.D.D., D.C.T., (Ph.D), (MBA)


Asst. Professor,
RAGHU College of Pharmacy,
Visakhapatnam.
www.raghupharmacy.com

Pharmacokinetics Solved Problems


www.pharmainfo.net/og/rcp/downloads

PROBLEM-8:
Following data is obtained for 4 formulations of pentoxyifylline in volunteers of average weight 50 kg.
Drug Product
i.v. solution
oral solution
oral capsule
oral S.R. tablet
SOLUTION-8:
Given data:
Drug Product

i.v. solution
oral solution
oral capsule
oral S.R. tablet

Dose
(mg/kg)
1.2
4.0
4.0
8.0

Dose (mg/kg)
1.2
4.0
4.0
8.0

AUC (mg. hr/lt)


450
822
736
1040

Dose in
mg /50kg
Di.v. = 1.2 x 50 = 60
Dsol = 200
Dcap = 200
DSR = 400

AUC (mg. hr/lt)

[AUC]i.v. = 450
[AUC]sol = 822
[AUC]cap = 736
[AUC]SR = 1040

a. What is the absolute bioavailability of the drug from capsule?

F=

[AUC]cap Di.v.
[AUC]i.v. Dcap

736 x 60
=
450 x 200

44,160
90,000

= 0.49 x 00 = 49%

b. What is the absolute bioavailability of the drug from S.R. tablet?

F=

[AUC]S.R Di.v.
[AUC]i.v. DS.R.

1040 x 60
=
450 x 400

62,400
1,80,000

= 0.346 x 00 = 34.6%

c. What is the relative bioavailability of capsule against oral solution?

Fr =

[AUC]cap Dsol
[AUC]sol Dcap

736 x 200
=
822 x 200

1,47,200
1,64,400

= 0.895 x 00 = 89.5%

d. What is the relative bioavailability of S.R. tablet against oral solution?

Fr =

[AUC]S.R. Dsol
[AUC]sol DS.R.

1040 x 200
=
822 x 400

2,08,000
3,28,800

= 0.632 x 00 = 63.2%

e. Which solid formulation shows better bioavailability?


Bioavailability of capsule (49%) is more than S.R. tablet (34.6%).

GOOD LUCK
www.pharmainfo.net/eswar

Reference: Bio-Pharmaceutics and Pharmacokinetics by: Brahmankar


: V. Venkateswarlu

Page 2 of 2

eswar@pharmainfo.net

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