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Bioavailability and Factors Affecting Bioavailability of drug
1. Factors Affecting
Bioavailability of drug
Ashutosh Gupta
M. Pharm (pharmaceutics)
From BIT Mesra Ranchi
Assistant Professor
at
Department of Pharmaceutics
College of Pharmacy
TMU Moradabad
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2. CONTENTS
Introduction of Bioavailability
Objective of bioavailability studies
Types of bioavailability
Factors Affecting Bioavailability
Pharmaceutical factors
Pharmacological factors
Route of administration
Bibliography
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3. Introduction of bioavailability
The rate and extent at which the active concentration of a drug is available
at the desired site of action.
Bioavailability=
𝑨𝑼𝑪 𝒐𝒇 𝒐𝒓𝒂𝒍
𝑨𝑼𝑪 𝒐𝒇 𝑰𝑽
*
𝑰𝑽 𝒅𝒐𝒔𝒆
𝑶𝒓𝒂𝒍 𝒅𝒐𝒔𝒆
In such cases, the dose available to the patient, called as bioavailable
dose. It often less than the administered dose.
The amount of drug that reaches the systemic circulation is called as
systemic availability.
The term bioavailable fraction F refers to the fraction of administered
dose that enters the systemic circulation.
𝐅 =
𝐁𝐢𝐨𝐚𝐯𝐚𝐢𝐥𝐚𝐛𝐥𝐞
𝐀𝐝𝐦𝐢𝐧𝐢𝐬𝐭𝐞𝐫𝐞𝐝 𝐝𝐨𝐬𝐞
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4. Primary stages of development of a suitable dosage foam for a new drug
entity to obtain evidence of its therapeutic utility.
Objective of bioavailability studies
Bioavailability studies are important in the-
Determination of influence of excipients, patient-related factors and
possible interaction with other drug on the efficiency of absorption.
Development of new formulations of the existing drugs.
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5. Control of quality of a drug product during the early stages of factors,
storages and stability on the drug absorption.
Comparison of availability of a drug substance from different dosage
forms or from the same dosage from produced by different manufactures.
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6. Types of bioavailability
There are two types of bioavailability
- Relative bioavailability
- Absolute bioavailability
Relative bioavailability
The relative bioavailability is the systemic availability of a drug after oral
administration is compared with that of oral standard of the same drug.
𝐅𝐫 =
𝐎𝐫𝐚𝐥 𝐝𝐨𝐬𝐞 (𝐝𝐫𝐮𝐠)
𝐎𝐫𝐚𝐥 𝐝𝐨𝐬𝐞 (𝐬𝐭𝐚𝐧𝐝𝐚𝐫𝐝)
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7. Absolute bioavailability
when the systemic availability of a drug administered orally is comparison
to its intravenous administration, is called as absolute bioavailability .
𝐅 =
𝑶𝒓𝒂𝒍 𝒅𝒐𝒔𝒆
𝐈. 𝐕 𝐝𝐨𝐬𝐞
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8. Factors affecting Bioavailability
There are various factors which affect the bioavailability of drug-
Pharmaceutical factors
Pharmacological factors
Route of administration
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9. Pharmaceutical Factors:
It is expected that, bioavailability of drugs to be in this decreasing
order-
Solutions > Suspension > Capsule > Tablet > Coated Tablet
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10. The Pharmaceutical factors include:
Particle Size
Salt Form
Crystal Forms
Nature of Excipients
Degree of Ionisation
Partition coefficient
The method of manufacturing
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