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Questions and Answers
The process of how the drug is moved from the site of administration into the ______ is called absorption.
The process of how the drug is moved from the site of administration into the ______ is called absorption.
bloodstream
The amount of drug that is moved to different body ______ is known as distribution.
The amount of drug that is moved to different body ______ is known as distribution.
tissues
The alteration and breakdown of a drug in the body is referred to as ______.
The alteration and breakdown of a drug in the body is referred to as ______.
metabolism
The removal of the drug from the body occurs through a process known as ______.
The removal of the drug from the body occurs through a process known as ______.
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Plasma protein binding can limit the ______ of active compounds.
Plasma protein binding can limit the ______ of active compounds.
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Orally administered drugs achieve a bioavailability level substantially lower than ______ due to incomplete absorption.
Orally administered drugs achieve a bioavailability level substantially lower than ______ due to incomplete absorption.
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Drugs and/or its metabolites are eventually eliminated from the body through the ______.
Drugs and/or its metabolites are eventually eliminated from the body through the ______.
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The study of what the drug does to the body is known as ______.
The study of what the drug does to the body is known as ______.
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The time for a drug to start a therapeutic ______ is referred to as onset.
The time for a drug to start a therapeutic ______ is referred to as onset.
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______ is the ability of the drug to bind with the receptor.
______ is the ability of the drug to bind with the receptor.
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An ______ is a molecule that activates a receptor to produce an effect similar to that of a physiological molecule.
An ______ is a molecule that activates a receptor to produce an effect similar to that of a physiological molecule.
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A ______ prevents the action of an agonist on a receptor but does not produce an effect of its own.
A ______ prevents the action of an agonist on a receptor but does not produce an effect of its own.
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The overall effect of two chemicals acting together is referred to as ______.
The overall effect of two chemicals acting together is referred to as ______.
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Half-life is the time required for the plasma concentration of the drug to reach ______% of its original administered concentration value.
Half-life is the time required for the plasma concentration of the drug to reach ______% of its original administered concentration value.
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Drugs administered intravenously offer a ______ onset compared to other routes of administration.
Drugs administered intravenously offer a ______ onset compared to other routes of administration.
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One of the disadvantages of IV drug administration is its high ______.
One of the disadvantages of IV drug administration is its high ______.
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Oral drug administration involves delivering medication through the ______.
Oral drug administration involves delivering medication through the ______.
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After absorption, substances from the intestines are delivered to the ______ via the portal vein.
After absorption, substances from the intestines are delivered to the ______ via the portal vein.
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The fraction of an orally administered drug that reaches systemic circulation is known as ______.
The fraction of an orally administered drug that reaches systemic circulation is known as ______.
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The first crucial factor after oral absorption is the efficient first pass ______ and metabolism of compounds by the liver.
The first crucial factor after oral absorption is the efficient first pass ______ and metabolism of compounds by the liver.
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In intravenous drug administration, the use of large fluid volume allows the use of ______ drugs.
In intravenous drug administration, the use of large fluid volume allows the use of ______ drugs.
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Study Notes
Pharmacokinetics
- Pharmacokinetics is the study of how drugs are absorbed, distributed, metabolized, and excreted by the body.
- Stages:
- Absorption: The process of drug movement from the site of administration into the bloodstream.
- Distribution: The movement of the drug from the bloodstream to the various tissues and organs in the body.
- Metabolism: The process in which the drug is altered or broken down by the body.
- Excretion: The removal of the drug or its metabolites from the body.
Bioavailability
- Bioavailability (F%) is the percentage of an administered dose that reaches the systemic circulation in an unchanged active form.
- It measures the fraction of the administered drug that reaches the systemic circulation and is available to exert its pharmacological effects.
Plasma Protein Binding & Drug Availability
- Many drugs bind to circulating plasma proteins (e.g., albumin, globulins).
- Drug binding to plasma proteins can affect bioavailability by controlling the passage of active compounds through biological membranes.
- Hydrophobic drugs may be transported in the aqueous environment of the human organism due to binding to plasma proteins.
- Drugs can exist in bound or free forms in the body.
Drug Half-life (t1/2)
- Half-life is the time required for the plasma concentration of a drug to decrease by 50%.
- It's important in determining:
- Dosing requirements.
- How long a drug remains in the body.
- The dosing interval.
- Time to achieve a plateau.
Routes of Drug Administration
- Enteral: oral, sublingual, rectal.
- Parenteral (injectable): intravenous, intramuscular, subcutaneous.
- Topical: intranasal, inhalation, intravaginal.
Intravenous Administration (IV)
- Advantages:
- Rapid onset of action.
- Precise control of drug concentration.
- Suitable for large fluid volumes.
- Can administer irritant drugs.
- Disadvantages:
- High cost.
- Difficulty.
- Inconvenient.
- Irreversible.
Oral Drug Administration
- Oral administration involves delivering medication through the mouth.
- Solid forms (tablets, capsules).
- Liquid forms (syrups, drops).
- Drugs often don't enter the bloodstream until they reach the stomach or intestines for absorption.
- Bioavailability is usually less than 100% due to incomplete absorption and/or first-pass metabolism by the liver.
First-Pass Effect
- Substances absorbed from the intestines go to the portal vein.
- The portal vein delivers these substances to the liver before distribution to other organs.
- Many drugs must pass through the liver, which is the primary site of drug metabolism.
- Enzymes in the liver convert prodrugs to active metabolites or convert active drugs to inactive forms.
Excretion
- Elimination of drugs or their metabolites from the body.
- Routes:
- Kidneys (urine).
- Gastrointestinal tract (GIT) (stool).
- Skin (perspiration).
- Lungs (expiration).
- Eyes (tears).
Pharmacodynamics
- Pharmacodynamics is the study of how a drug affects the body.
- Key parameters:
- Onset: the time a drug takes to start having an effect.
- Peak: the time a drug reaches its maximum therapeutic effect.
- Duration: the time a drug's concentration is sufficient to produce a therapeutic response.
Receptors and Mechanism of Drug Action
- Receptors are sites on the organism to which drugs bind to initiate their effects.
- Drug action can involve:
- Action on cell membranes.
- Action on metabolic processes within the cell (e.g., enzyme activation/inhibition).
- Action outside the cell (e.g., osmotic diuretics, antacids).
Drug Receptor Characteristics
- Affinity: A drug's ability to bind to a receptor.
- Efficacy: A drug's ability to produce a desired response upon receptor binding.
- Potency: The amount of drug needed to elicit a specific response.
Drug-Receptor Interactions
- Agonists: Molecules that activate receptors to produce an effect similar to that of a physiologic molecule.
- Antagonists: Molecules that block the action of agonists on receptors without having their effect on the receptor. However, they do not have their effect on the receptor.
- Partial agonists: Molecules that activate receptors to produce sub-maximal effects but also antagonize the actions of full agonists.
Drug Effects of Drug Combinations
- Effects of combining drug therapy can follow the rules from mathematics:
- Addition (1 + 1 = 2): The combined effect is the sum of individual effects.
- Synergism (1+1 >2): The combined effect exceeds the sum of individual effects.
- Potentiation (0 + 1 = 2): One drug that has no effect enhances the effect from the second drug.
- Antagonism (1 + 1 = zero): one drug inhibits the effect of the other drug.
Drug Tolerance and Intolerance
- Drug tolerance: Decreased response to a drug after repeated administration.
- Drug intolerance: Side effects observed with a therapeutic dose.
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Description
Test your knowledge on the fundamental concepts of pharmacology, including absorption, distribution, metabolism, and excretion of drugs. This quiz will challenge your understanding of how drugs interact within the body and the implications of plasma protein binding.
