Pharmacokinetics Flashcards by Iseoluwa Ojo

Pharmacokinetics describes the fate of a drug within the body
-It simple refers to “what the body does to the drug”
-These fate includes

_____
______
_____
______

ABSORPTION
DISTRIBUTION
METABOLISM
EXCRETION

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Administration of a drug
-is the initial introduction of a drug into the body
-Drugs are introduced into the body either
______ or ______

Enterally or Parenterally

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ENTERAL means of administering drugs

____

Oral

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PARENTERAL means of administering drugs

Mention 7

Intravenous
Intramuscular
Subcutaneous
Inhalational
Topical
Transdermal
Intrathecal/Intraventricular

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Absorption
-is the transfer of drug from the _____ to ____

site of administration to the bloodstream

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MEASURE OF DRUG ABSORPTION

Bioavailability
- is the ______

relative amount of the administered drug that reach the systemic circulation

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Drugs administered through Intravenous (IV) route have ____% bioavailability

100

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Formula for bioavailability of drugs:

Absolute bioavailability = _____/ ____ × —-

Relative bioavailability =_____/ ______ × 100

AUC Oral

AUC IV

100

AUC (test)

AUC (standard)

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Bioequivalence
Two drug formulations with _________ as well as the _______ are bioequivalent

the same bioavailability

same rate of absorption

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Distribution
is the delivery of a drug from the _____ to ______

systemic circulation to tissues

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MEASURE OF DRUG DISTRIBUTION
Volume of distribution (Vd)
-It is the _______

Formula:
Vd = _____/Co
Co is the _______

fluid volume in the body into which the drug is contained

Dose

concentration of the drug in the plasma at time 0

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Tissues that store large concentration of drugs are
____
_____

Fat
Bones

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Metabolism Of drugs

-Characterized by the conversion of drugs from its ___PHILIC nature to execrable ___PHILIC products, through specialized enzymatic systems

LIPO

HYDRO

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SITES OF DRUG METABOLISM

Mention 4

Liver
Kidney
Small Intestine
Lungs

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PRODUCTS OF DRUG METABOLISM

Mention 4 scenarios

Inactive to active
Active to inactive
Active to active
Active to toxic

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PHASES OF DRUG METABOLISM

Phase I
FUNCTIONALIZATION REACTION
-A ___ is introduced into the drug to make it ____

-Enzymes involved a special enzymes called _____ enzymes found in the ____

functional group

more polar

CYTOCHROME P-450

SER

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Examples of Phase I reaction includes:

____
_____
_____

Oxidation
Reduction
Hydrolysis

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Enzymes involved in phase 1 oxidation reactions

CytochromeP450 Oxidase

dehydrogenase

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Enzymes involved in phase 1 reduction reactions

Cytochrome p450 reductase

Decarboxylase

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Enzymes involved in phase 1 hydrolysis reactions

Estarase

Amidase

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Phase II
CONJUGATION REACTION
-An _____ substance is added to the drug to make it hydrophilic
-Examples of Phase II reaction

Mention 5

endogenous

Glucuronidation
*Sulfation
*Methylation
*Acetylation
*Glutathione conjugation

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Glucuronidation
Sulfation
Methylation
Acetylation
Glutathione conjugation
Glycine conjugation

Mention the enzymes involved in the reactions

Glucoronyl Transferase

N-acetyl Transferase

Sulfo Transferase

Methyl Transferase

Glutathione conjugation

Glycine conjugase

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Enzyme Induction
-Induces Microsomal Cytochrome P-450 enzyme
-___eases metabolism of co-administered drugs
-May lead to _____

Incr

therapeutic failure

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Enzyme Inhibition
Inhibitors of Cytochrome P-450
___eases metabolism of co-administered drugs
May lead to ____

Decr

drug toxicity

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MECHANISM OF HEPATIC EXCRETION _______ _______

Hepatic secretion Enterohepatic circulation

Enterohepatic circulation -from ______ to ____ to ___ to ____ to ____

duodenum to ileum capillary bed to portal vein to liver

__% bile salts is excreted into faeces

a charged drug can cross the plasma membranes T/F

F can’t

for absorption, acidic drug wants ____ environment. Basic drugs wants ____ for excretion, acidic drugs wants ___ environment, basic drugs wants ____ environment

acidic basic basic acidic

MEASURE OF DRUG EXCRETION Half-life (t1/2) -It is the time taken for ______ Elimination rate (Kel) -It is the ________ Clearance (CL) -It is the _______

the concentration of drug in the blood to fall by half its original value. fraction of drug that is eliminated at a given time volume of blood or plasma cleared of a drug in unit time

ELIMINATION KINETICS Zero-order kinetics -Elimination of ________ per unit time -Rate of elimination is (dependent or independent?) of drug concentration -Half-life is ( dependent or independent?) to the drug concentration

constant amount of a drug independent dependent

Zero-order kinetics Examples Mention 4

Ethanol Heparin Phenytoin Aspirin

First-order kinetics -Elimination of ____ of a drug per time -Rate of elimination is (dependent or independent?) of the drug concentration -Half-life is (dependent or independent?) of drug concentration Examples ____

constant percentage Dependent independent MOST DRUGS

PARACETAMOL Administration- Bioavailability- Metabolism in the liver - phase 1: phase 2: Half-life- Elimination kinetics- zero or first Excretion is by??

Oral 63-89% Oxidation Sulphation and glucoronidation 1.9-2.5 hours First order Kidney

Enteral administration is administering a drug by ______

mouth

______ administration is the safest and most common, convenient, and economical method of drug administration.

Enteral

The drug may be swallowed, allowing oral delivery, or it may be placed _________ (sublingual), or _____ (buccal), facilitating direct absorption into the bloodstream

under the tongue between the gums and cheek

A wide range of oral preparations is available for drugs that can’t withstand the low ph of the stomach including ______ and ______ preparations.

enteric-coated and extended-release

Enteric coating is useful for certain drugs (for example, ______) that are acid unstable. Drugs that are irritating to the stomach, such as _______, can be formulated with an enteric coating that only dissolves in the small intestine, thereby protecting the stomach.

omeprazole aspirin

the half-life of oral morphine is ___

2 to 4 hours

Example of a drug poorly absorbed in the GIT

Heparin

Example of a drug that is unstable in the GIT

Insulin, omeprazole

________ is the most common parenteral route

IV injection

Injected drugs can be recalled by activated charcoal T/F

Subcutaneous injection route should not be used with drugs that cause _______, because ______ and ______ may occur.

tissue irritation severe pain and necrosis

Drugs commonly administered via the subcutaneous route include ______ and ______

insulin and heparin.

Examples of drugs administered via Oral inhalation include bronchodilators, such as ______, and corticosteroids, such as _____.

albuterol fluticasone

Desmopressin is administered ______ in the treatment of _________

intranasally diabetes insipidus.

Topical application is used when _____________

a local effect of the drug is desired.

Transdermal: This route of administration achieves systemic effects by application of drugs to ______, usually via a ______

the skin transdermal patch

Rectal: Because 50% of the drainage of the rectal region ________, the ___________ is minimized with rectal administration.

bypasses the portal circulation biotransformation of drugs by the liver

The vast majority of drugs are absorbed by ____ mechanism

Passive diffusion

_____-soluble drugs penetrate the cell membrane through aqueous channels or pores, whereas ____-soluble drugs readily move across most biologic membranes

Water lipid

Mechanisms of absorption of drugs from the GI tract Passive diffusion can be saturated Facilitated diffusion can be saturated Active transport can be saturated T/F

F T T

The lower the pKa of a drug, the more _____ it is

acidic

Which has more blood flow and hence better for absorption? Stomach or small intestine?

Small intestine

First-pass hepatic metabolism: When a drug is absorbed from the GI tract, it enters the _____ before entering the _____

portal circulation systemic circulation

more than 90% of _______ is cleared during first-pass metabolism.

nitroglycerin

rocuronium, a _________ is administered by ______ route

Neuromuscular blocker IV

if the medication is delivered too rapidly and high concentrations are reached too quickly , It may also ______, induce ______, or cause other adverse reactions

precipitate blood constituents hemolysis

Drugs administered IM can be in ______, which are absorbed rapidly, or in specialized ______, which are absorbed slowly.

aqueous solutions depot preparations

Depot preparations often consist of a _____ of the drug in a ______ vehicle such as polyethylene glycol. As the vehicle diffuses out of the muscle, the drug ______ at the site of injection. The drug then _______, providing a ________ over an extended period of time.

suspension; nonaqueous Precipitates ; dissolves slowly sustained dose

Subcutaneous administration route should not be used with drugs that cause _______, because ________ and _______ may occur. Drugs commonly administered via the subcutaneous route include ______ and _____

tissue irritation severe pain and necrosis insulin and heparin.

The _____ typically delays or prevents the absorption of drugs into the central nervous system (CNS). When local, rapid effects are needed, it is necessary to introduce drugs directly into the _________

blood–brain barrier cerebrospinal fluid.

A drug passes through membranes more readily if it is (charged or uncharged ?)

Uncharged

Factors that affect route of administration ______ of Drug ________ of treatment _____ of action Desired _______ _________

Nature Duration Site onset of action Consciousness

FACTORS AFFECTING DRUG ABSORPTION _______ of Administration _________ of drug _______ ______ _____ flow _______ of absorption site _________ at absorption site Presence of ______

Route Solubility Concentration pH Blood Surface area Contact time P-glycoprotein

Out of AADME, which ones do age affect

Distribution Metabolism

Out of AADME, which ones do PH affect

Absorption Distribution Excretion

Arrange in terms of decreasing absorption rate Skin; gut; muscle

Muscle, skin, gut

FACTORS AFFECTING DRUG DISTRIBUTION ______ of drug ____ Binding to ______ Binding to _____ Organ or tissue size and perfusion _____ ______ ____ _______ ______ state Drug ______

Lipophilicity pH plasma proteins Tissues Age Pregnancy Obesity Diet Disease interaction

MEASURE OF DRUG DISTRIBUTION __________

Volume of distribution (Vd)

Levodopa is converted from _____ to _____

Inactive to active

Epinephrine is from active to _____ Panadol is from active to_____

Inactive Toxic

Salivary excretion is by _______ Pulmonary excretion is by _______________ Tears excretion is by _________ Sweat excretion is by ________ Hair excretion is by _________ Breast excretion is by __________

Passive diffusion Passive diffusion and expiration Passive diffusion Passive diffusion Unknown…maybe deposition from the capillaries Passive diffusion

Codeine Weak acid or weak base?

Weak base

Most rapid route of absorption is IV T or F

F Inhalational

Pharmacokinetics Flashcards

(77 cards)