Prelim Biopharmaceutics Flashcards by Euwella Gloria

effect of rate & extent of drug
absorption

Bioavailability

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“what the body does to the drug”
-involves experimental and theoretical studies
-uses statistical methods

Pharmacokinetics

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involves multidisciplinary approach to
individually optimize dosing strategies based on
patient disease state & patient specific
consideration

Clinical Pharmacokinetics or Therapeutic Drug
Monitoring (TDM

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What are the Factors considered in TDM

Disease
Age
Gender
Genetic
Ethnic difference

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pharmacokinetic differences of drugs in
various population groups

Population Pharmacokinetics

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What are the monitoring parameters

Plasma drug concentration
pharmacodynamic endpoint

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Common drugs monitored

Aminoglycosides
Anticonvulsants
Vancomycin
Digoxin
cancer chemotherapy
drugs with NTI

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concentration of drug at the site of action
-biochemical effect of the drug
-physiologic effect of the drug
-“what the drug does to the body

Pharmacodynamic

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refers to drug dose in body fluids

Drug exposure

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direct measure of the pharmacological
effect of the drug

Drug response

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application of pharmacokinetic principles
to the design, conduct and interpretation of
drug safety evaluation studies & in validating
dose-related exposure in animals

Toxicokinetic

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study of adverse effects of drugs and toxic
substances in the body

Clinical Toxicology

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Usually involved in toxicity cases:

Acetaminophen
Salicylates
Morphine
TCAs

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most direct approach to assessing
pharmacokinetics of the drug in the body.

Blood plasma

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devoid proteins
from filtered plasma

Unbound drug concentration

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with proteins
from unfiltered plasma

Total plasma drug concentration

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time required for a drug to reach
MEC

Onset time

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difference between
the onset time & time for the drug to decline
back to MEC.

Duration of drug action

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concentration between MEC and MTC; ratio
between toxic and therapeutic dose.

Therapeutic window/Therapeutic index

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maximum drug
concentration

Peak plasma level

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time of maximum
drug level.

Time for peak plasma level-

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amount of drug
absorbed systematically; measure of the amount
of drug in the body

Area under the curve (AUC)

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to ascertain if the drug
reached the tissues & reach the
proper concentration within the
tissue

Drug concentration in
tissues

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drugs that are bound to
plasma protein are inactive drugs

Plasma protein binding
(PPB)

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indirect method to ascertain bioavailability of a drug

Drug concentration in urine and feces

reflect drug that has not been absorbed or expelled by biliary secretion after systemic absorption.

Feces

approximates free drug level; secondary indicator

Drug concentration in saliva

application of science to personal injury, murder and other legal proceedings -used in investigation -concerned with medico-legal aspects of harmful effects of chemicals on humans and animals

Forensic drug measurements

Best indicator:

plasma, urine, feces

-alter normal physiologic function or process -interaction of drug molecules and cellular components (receptor) alter the functions of the latter.

Functional Modifiers

Supplements existing endogenous substances that are deficient or lacking

Replenishers

Agents used to determine the presence or absence of a condition or disease.

Diagnostic Agents

Used to kill or inhibit growth of cells considered as foreign to the body

Chemotherapeutic agents

a molecule that binds to the receptor

LIGAND

a drug that binds to (affinity) and activates receptor (intrinsic activity)

Agonist

a drug that produces 100% of the maximum possible biologic response.

Full agonist

-binds to or block receptors (affinity only) -prevents binding of agonist -opposite effect of agonist

Antagonist

binds reversibly to the same active site of an enzyme as an agonist; can be overcome by increasing the concentration of the agonist. Ex: Enzyme agonist

Competitive antagonist

binds irreversibly to the different active site of an enzyme as an agonist; cannot be overcome by increasing the concentration of the agonist.

Non-competitive antagonist

a drug that binds to a different receptor, producing an effect opposite to that produced by the drug it is antagonizing

Physiologic Antagonist

a drug that interacts directly with the drug being antagonized to remove it or to prevent it from reaching its target (direct effect)

Chemical Antagonist

macromolecule typically made of proteins that interacts with endogenous ligand or drug to mediate an effect.

RECEPTOR

is caused by continuous prolonged exposure of receptors to drugs that discrupt the homeostatic equilibrium; due to altered levels of receptors.

Down Regulation

-result of down regulation; effect of subsequent exposure of the receptor to the same concentration of the drug is reduced. -Increased concentration of the drug is required to produce the same effect as the initial concentration.

Desensitization

-occurs when target cells are subject to long term exposure to receptor antagonists followed by abrupt cessation of administration of the drug. -Up-regulation through new synthesis of new receptors

Hyperactivity/supersensitivity

-graph of response versus the logarithm of the dose yields the efficacy (Emax) and potency (ED50).

GRADED-DOSE-RESPONSIVE CURVE

measured by its maximum effect.

Efficacy

related to the amount of drug necessary to cause an effect -related in the ED50 or the dose at 50% of the Emax -The smaller the ED50, the greater the potency, the greater the potency of the drug.

Potency

-graph of the number of patients that responds by a specified dose. -median effective (ED50), median toxic (TD50), median lethal dose (LD50) can be obtained.

QUANTAL DOSE-RESPONSIVE CURVE

-The pharmacological effects depends on the percentage o f the receptors occupied drug must have affinity to receptor. -If all receptors occupied = maximum effect

.Hypothesis of Clark

-The drug molecule must “fit into a receptor” like a “key fits into a lock”

Lock and key theory

Postulates a complementary relationship between the drug molecule and its active site. -Provides for mutual conformational changes between the drug and its receptor.

Induced-fit theory

-Occupational theory of response. -Postulates that for a structurally specific drug, the intensity of the pharmacological effect is directly proportional to the number of receptors occupied by the drug. -affinity + intrinsic activity or efficacy -effectiveness lasts as long as the receptors are occupied

Hypothesis of Ariens and Stephenson

-Effectiveness = occupation + proper stimulus

Hypothesis of Paton (Rate theory)

When two drugs with the same effect are given together, resulting in a drug effect that is equal in magnitude to the sum of the individual effects of the 2 drugs.

Addition (1+1=2)

* Alcohol + Barbiturates: ↑ seddation * Alcohol + Antihistamines: ↑ sedation * Alcohol + CNS depressants: ↑ sedation * Alcohol + Chloral hydrate: ↑ sedation * Alcohol + Chlorpropramide: ↑ hypoglycemic effects * Flecainide + Verapamil: ↑ negative inotropic and chronotropic effects

Examples of Addition

When 2 drugs with the same effect are given together, producing a drug effect that is greater in magnitude than the sum of the individual effects of the 2 drugs.

Synergism (1+1=3)

Sulfamethoxazole + Trimethoprim (↑ bactericidal effect)

Example of Synergism

-Occurs when one drug, lacking an effect of its own, increases the effect of another drug that is active.

Potentiation (1+0=2)

Amoxicillin + Clavulanic acid: ↑ Amoxicillin's antibiotic effect * Ampicillin + Sulbactam: ↑ Ampicillin's antibiotic effect * Piperacillin + Tazobactam: ↑ Piperacillin's antibiotic effect * Levodopa + Carbidopa: ↑ Levodopa's effect

Examples of Potentiation

Drug inhibits the effect of the other

Antagonism (1+1=0)

* Phenoxybenzamine + Catecholamines: management of pheocromocytoma * Warfarin + Vitamin K: antidote for Warfarin toxicity * Opioids + Naloxone: antidote for Opioid toxicity * Benzodiazepine + Flumazenil: antidote for Benzodiazepine toxicity * Atropine + Physostigmine: antidote for Atropine toxicity * Procaine + Sulfonamides: antagonism of Sulfonamide's antibacterial activity * Heparin + Protamine SO4: antidote for Heparin toxicity

Examples of Antagonism

mathematical terms used to describe quantitative relationship relationship concisely

Model

practical, but not very useful in explaining the mechanism of the actual process by which the drug is absorbed, distributed & eliminated in the body

Empirical Model

Physiologically-based model (Flow model)

where there is blood, there is drug

a very simple and useful tool in pharmacokinetics.

Compartmentally-based model

-overly simplistic view of drug disposition in the human body, a drug’s pharmacokinetic properties can frequently be described using a fluid-filled tank model

specific, involves drug carriers

Multicompartment model

-most common compartment model -the total amount of drug in the body is simply the sum of drug present in the central (plasma) compartment plus the drug present in the tissue compartment.

Mamillary model

consists of one or more compartments around a central compartment like satellites

Catenary model

Prelim Biopharmaceutics Flashcards

Exam (70 cards)