(AD)ME Flashcards
ADME
Absorption, Distribution, Metabolism, Excretion
Pharmacokinetic (PK) Phase
Dose, dosage form, frequency, and route of administration as related to drug level vs time.
Pharmacodynamic (PD) Phase
The concentration of a drug at the site of action as related to efficacy.
How are the Metabolism and Excretion phase combined into one term?
Elimination
Route of Administration
The pathway that the drug enters the body with respect to sites of absorption
Distribution
The partitioning of the drug through various organs and site in the body.
Volume of Distribution
The APPARENT volume into which the drug is distributed which is determined by amount of drug administered, divided by initial drug concentration. For example, a very small pill with a small concentration detectable in the blood would be expected to have been diluted by a VERY large volume. Hence it would have a large volume of distribution.
Drug Metabolism
The process in which a drug is biochemically modified through a series of reactions (often enzymatic).
What are the ideal features of a drug in the context of ADME?
Transported by body fluids, tranverses biological membranes, does not readily dilute and distribute through the entire body, reaches relevant sites of actions, and correctly acts on its target.
Advantages and disadvantages of Route: Oral
Noninvasive and good for repeated administration, but has heavy first pass effect and requires patient compliance
Advantages and disadvantages of Route: Sublingual
Rapid entry without first pass effect, but limited by taste
Advantages and disadvantages of Route: Rectal
Avoids undesirable oral complications and less first pass effect but is invasive
Advantages and disadvantages of Route: Parenteral
100% absorption, rapid onset, but requires physician administration
Bioavailability
The concentration at which a specific drug is available for reaction at a given time
Paracellular Pathway
Drug entry into an organ by traveling through the tight junctions between cells
Trancellular Pathway
Travelling through a cell via Endocytosis, active transport, passive transport, facilitated diffusion
What molecules can pass a cell membrane?
Small hydrophobic molecules like oxygen and small uncharged polar molecules like water (but note that most cells also use channels for them too, like aquaporins)
Endocytosis
The cell membrane encompasses a material to allow it into the cell
Fick’s Law of Diffusion
The rate of transport in a membrane is a product of surface area, the diffusion coefficient of a material and the relative concentration of the material reaching equilibrium. That product is then divided by thickness of said membrane.
Facilitated Diffusion
Allowance of chemicals to passively travel through a designated channel
Active Transport
Using energy to transport a material against its concentration gradient.
Solute Carrier (SLC)
Used to transport medium sized molecules in passive transport
ATP Binding Cassette
Uses ATP to actively transport chemicals.
Uniport
Passive transport through one channel in one direction with one molecule
Symport (Cotransport)
Two different types of molecule travel in the same direction passively, one’s gradient might assist the other’s
Antiport
Two different types of molecule travel in opposite direction, one’s gradient might assist the other
P-glycoprotein (PGP)
Actively pumps foreign material out of a cell, which then contributes to the drug resistance of specific organs.
What is the most important section of the small intestine in drug absorption?
Jejunum
What affects bioavailability of Oral drugs?
Physiochemical properties, pharmaceutical ingredients, dosage form, patient factors, and drug metabolism
What system is the Lymphatic attached to?
The circulatory system
Subcutaneous
Below the top layer of skin
Intramuscular
Into the muscle far below the skin (Painful)
Intravenous
Into the veins below the skin
Transdermal
On top of the skin via patch or ointment
Implantation
A delivery system that remains in the skin for an extended period of time
One component model
The drug completely disperses in the body evenly
Two component model
The drug concentrates in organs after administration before eventually distributing in the entire body
Protein Binding and Volume of Distribution
Proteins bind to the drug and limits its distribution, usually in relation to the drug’s charge while in the plasma
Dose
The target blood concentration of the drug multiplied by the volume of distribution
Clearance
The removal of a drug from a volume of plasma in a given unit of time. This number is JUST the volume of plasma, not how much drug was removed. Think “volume of blood that was filtered by the kidneys”
Passive reabsoprtion
The process in which useful chemicals are returned to the bloodstream by the kidney. Drugs will be excreted or reabsorbed based on relative pH
k (in drug elimination)
The fraction of drug removed from the body per hour. Relates to the volume of distribution as clearance is constant
Half Life
The time it takes for half the drug to leave the body
Steady state drug elimination
The point at which drug is added and removed at the same rate in a body
