, lOMoARcPSD|70468202
Week 1
Term Definition
Bioavailability: The fraction of an administered dose of a drug that reaches
systemic circulation. It is critical in determining the correct dosage for oral
medications versus other forms like intravenous (IV) administration.
Half-Life: The time it takes for the plasma concentration of a drug to
reduce to half its original value. This concept is crucial in determining drug
dosing frequency to maintain therapeutic levels.
First Pass Effect: A phenomenon where the concentration of a drug is
significantly reduced after metabolism in the liver before it reaches systemic
circulation. This is particularly important for oral drugs, which pass through
the liver and may be extensively metabolized, reducing their bioavailability.
Plasma Protein Binding:Drugs in the bloodstream may bind to plasma
proteins, mainly albumin, which affects their distribution and free drug levels
in the blood.
Clearance: A pharmacokinetic parameter that measures the efficiency with
which a drug is removed from the body.
Xenobiotics: Substances that are foreign to the body can potentially
introduce adverse effects. Medications are one example. The extent of
adverse effects correlates with the rate of absorption, distribution,
metabolism, and excretion of the medication, which determines the degree
of chemical exposure in the body.
Drug Absorption
Oral (PO)
Oral drug administration is the least bioavailable route due to barriers like
epithelial cells lining the GI tract and the variability in gastric and intestinal
conditions. Oral preparations include tablets (regular and enteric-coated) and
sustained-release forms. Enteric-coated and sustained-release tablets should
not be crushed, as this affects drug absorption and effectiveness.
Advantages include convenience and safety, as oral drugs can be
reversible in case of overdose if caught in time (gastric lavage,
activated charcoal, etc.).
, lOMoARcPSD|70468202
Disadvantages include variability of absorption (gastric emptying, food
consumption, etc.) and the need for client cooperation (the ability to
swallow pills independently).
Intravenous (IV)
Offers 100% bioavailability with no absorption required since the entire dose
is injected into the bloodstream.
Advantages include rapid onset and precise control of drug levels
(including the ability to titrate).
Disadvantages include higher cost, risk of infection, and irreversibility
in case of overdose (unless a reversal agent exists).
Intramuscular (IM) and Subcutaneous (SubQ)
IM and SubQ routes also have high bioavailability with rapid absorption.
Advantages include usefulness for medications with poor water
solubility or depot preparations that slowly release the drug.
Disadvantages include client discomfort with administration and risk of
infection.
Other Routes
Topical, transdermal, sublingual, inhalation, suppository, direct injection to
the site of action, intraocular, intrathecal, otic, buccal, vaginal, and
intranasal routes each have unique absorption characteristics.
Factors impacting absorption
Drug Factors Affecting Absorption
Characteristics of a drug affect absorption, including:
The rate of drug dissolution affects how quickly the drug dissolves and
becomes available for absorption.
The drug formulation (extended-release, immediate release, etc.) also
affects drug absorption as some drugs are designed to be absorbed
immediately, while some are designed to be absorbed over a longer
time.
Drugs that are more lipid soluble are absorbed more readily as they
can directly penetrate cell membranes (primarily made of lipids). Drugs
Week 1
Term Definition
Bioavailability: The fraction of an administered dose of a drug that reaches
systemic circulation. It is critical in determining the correct dosage for oral
medications versus other forms like intravenous (IV) administration.
Half-Life: The time it takes for the plasma concentration of a drug to
reduce to half its original value. This concept is crucial in determining drug
dosing frequency to maintain therapeutic levels.
First Pass Effect: A phenomenon where the concentration of a drug is
significantly reduced after metabolism in the liver before it reaches systemic
circulation. This is particularly important for oral drugs, which pass through
the liver and may be extensively metabolized, reducing their bioavailability.
Plasma Protein Binding:Drugs in the bloodstream may bind to plasma
proteins, mainly albumin, which affects their distribution and free drug levels
in the blood.
Clearance: A pharmacokinetic parameter that measures the efficiency with
which a drug is removed from the body.
Xenobiotics: Substances that are foreign to the body can potentially
introduce adverse effects. Medications are one example. The extent of
adverse effects correlates with the rate of absorption, distribution,
metabolism, and excretion of the medication, which determines the degree
of chemical exposure in the body.
Drug Absorption
Oral (PO)
Oral drug administration is the least bioavailable route due to barriers like
epithelial cells lining the GI tract and the variability in gastric and intestinal
conditions. Oral preparations include tablets (regular and enteric-coated) and
sustained-release forms. Enteric-coated and sustained-release tablets should
not be crushed, as this affects drug absorption and effectiveness.
Advantages include convenience and safety, as oral drugs can be
reversible in case of overdose if caught in time (gastric lavage,
activated charcoal, etc.).
, lOMoARcPSD|70468202
Disadvantages include variability of absorption (gastric emptying, food
consumption, etc.) and the need for client cooperation (the ability to
swallow pills independently).
Intravenous (IV)
Offers 100% bioavailability with no absorption required since the entire dose
is injected into the bloodstream.
Advantages include rapid onset and precise control of drug levels
(including the ability to titrate).
Disadvantages include higher cost, risk of infection, and irreversibility
in case of overdose (unless a reversal agent exists).
Intramuscular (IM) and Subcutaneous (SubQ)
IM and SubQ routes also have high bioavailability with rapid absorption.
Advantages include usefulness for medications with poor water
solubility or depot preparations that slowly release the drug.
Disadvantages include client discomfort with administration and risk of
infection.
Other Routes
Topical, transdermal, sublingual, inhalation, suppository, direct injection to
the site of action, intraocular, intrathecal, otic, buccal, vaginal, and
intranasal routes each have unique absorption characteristics.
Factors impacting absorption
Drug Factors Affecting Absorption
Characteristics of a drug affect absorption, including:
The rate of drug dissolution affects how quickly the drug dissolves and
becomes available for absorption.
The drug formulation (extended-release, immediate release, etc.) also
affects drug absorption as some drugs are designed to be absorbed
immediately, while some are designed to be absorbed over a longer
time.
Drugs that are more lipid soluble are absorbed more readily as they
can directly penetrate cell membranes (primarily made of lipids). Drugs
