Pharma 1 Flashcards
What’s absorption
Distrubution
Metabolism
Elimination
Drug movement from its site to administration into the blood
Transfer of the drug in and out of tissue
Metabolism is biotransformation chemical changes mainly in liver
Elimination is losing of body from the body
What does it mean pharmaceutical form
Physical form of a drug
What are the 4 steps of a medicine til it appear in the blood
Disintegration of the tablet
Dissolution
Absorption
Appearing in the blood
Physical factors that influencing absorption
Blood flow in the intestine is much higer and intense than in the stomach
Total surface area which is higher in the intestine microvili
Contact time
For example diarrhea or food in the stomach or parasympathetic or sympathetic input can effect absorption a lot
What’s presystemic metabolism and when does metabolism accrue?
Metabolism accrue before the drug reaches systemic circulation and its called presystemic metabolism
How to count bioavailability? And what’s it
It’s the amount of a drug actually enter your bloodstream and available for your body to use it
Bioavailability (F)= ( AUCoral DEVIDE by AUCIV ) ×100=
What factors effect bioavailability
Solubility of the pharmaceuticals form
Nature of the Pharmaceuticals
Destruction of the pharmaceuticals
First pass metabolism
What’s biological and therapeutic equivalent
And what does biological equivalence compare
Two drugs are considered biologically equivalent if the release the same amount of medicine at the same rate into the blood
Comparable bioavailability
And comparable max plasma level
Therapeutical equivalent are two blood if they biologically equivalent and worked equally good to treat the same condition
Comparable safety and afficianty
When is the generic medicine results and preclinical test and clinical trails are not required?
If the medicinal product has the same qualitative and quantitative substance and same pharmaceutical form as the original medicine form. And same bioequivavalnce
So in short
Quality and quantity and its form and bioequivalence should be the same
What’s diestribution and is this process is reversible
Systemic affect occurs after distribution or before distribution?
It’s a distrubtion in which the drug reversible leaves the blood stream and enter extra cellular fluid or cell
And yes this process is reversible
Systemic effect occurs after distribution for local effect systemic distribution is not required
What factors effect the rate of distribution
Blood flow to the tissue
Capillary permeability
Drug structure
Protein binding
What is Volume of Distribution (Vd)?
Answer: It’s a theoretical concept that tells us how widely a drug spreads in the body. It helps us understand if a drug stays in the blood or spreads into tissues.
What is the formula for Volume of Distribution (Vd)?
Vd= D delad C
D = Dose of the drug.
C = Concentration of the drug in the blood.
What does a small Vd mean?
What does a large Vd mean?
It means the drug mostly stays in the blood (e.g., heparin)
means the drug spreads widely into tissues (e.g., ethanol).
What are the compartments of distribution?
These are the “spaces” in the body where a drug can go, such as:
Plasma/Blood (about 4 L).
Extracellular Fluid (about 14 L).
Total Body Water (about 42 L).
Other sites (e.g., fetus).
Which compartment do large molecules or protein-bound drugs (like heparin) stay in?
Which compartment do small, water-loving drugs (like aminoglycosides) spread into?
Which compartment do small, fat-loving drugs (like ethanol) spread into?
What does apparent volume of distribution (Vd) tell us?
They mostly stay in the plasma/blood (small Vd).
They spread into the extracellular fluid (medium Vd).
They spread into total body water, including inside cells (large Vd).
It tells us whether a drug stays in the blood (small Vd) or spreads into tissues (large Vd).
Drugs Binding to plasma protein tell me what’s that
What is the significance of free (unbound) drug?
What are Class I drugs?
What are Class II drugs?
What happens when a Class II drug is given with a Class I drug?
When drugs enter the bloodstream, many of them bind to plasma proteins (like albumin). However, only the free (unbound) drug is active and can interact with tissues or receptors to produce an effect. The bound drug is inactive and acts as a “reservoir” in the blood.
Only the free drug is active and can produce a therapeutic effect. Bound drug is inactive.
Class 1 Drugs with a low dose, high binding to plasma proteins, and a high bound fraction (e.g., warfarin)
Class 2 Drugs with a high dose, low binding to plasma proteins, and a high free fraction (e.g., sulfonamides).
The Class II drug displaces the Class I drug from plasma proteins, increasing the free fraction of the Class I drug, which can lead to toxicity.
Summary:
Free Drug: Only the free (unbound) drug is active.
Class I Drugs: Low dose, high binding to proteins (most of the drug is bound).
Class II Drugs: High dose, low binding to proteins (most of the drug is free).
Displacement: Class II drugs can displace Class I drugs from proteins, increasing the free fraction of Class I drugs.
What is the purpose of Phase I reactions in drug metabolism?
What happens during Phase II reactions?
Why is biotransformation important for drug elimination?
To convert lipophilic (fat-soluble) drugs into more polar (water-soluble) molecules, making them easier to excrete.
The drug is conjugated with a polar molecule (e.g., glucuronic acid, sulfuric acid) to further increase its water solubility and prepare it for excretion.
It converts fat-soluble drugs into water-soluble forms, allowing them to be excreted by the kidneys and preventing toxicity.
What is an enzyme inducer, and how does it affect drug plasma levels?
What is an enzyme inhibitor, and how does it affect drug plasma levels?
An enzyme inducer increases the production or activity of liver enzymes, causing drugs to be broken down faster. This leads to decreased plasma levels and reduced drug effect.
What is an enzyme inhibitor, and how does it affect drug plasma levels?
Answer: An enzyme inhibitor blocks or reduces the activity of liver enzymes, causing drugs to be broken down slower. This leads to increased plasma levels and increased drug effect (or toxicity).
Q: What is the elimination half-life (t½ elim) of a drug?
How does distribution half-life (t½ α) differ from terminal half-life (t½ β)?
The half-life (t½) of a drug is the time required for its plasma concentration to decrease by 50% through elimination, distribution, or metabolism. It is a critical pharmacokinetic parameter that determines:
How often a drug must be dosed.
How long it takes to reach steady state.
How long the drug remains in the body after stopping.
Time for plasma concentration to decrease by 50% due to metabolism/excretion. Determines dosing frequency (e.g., t½ = 6h → dose every 6h).
t½ α: Rapid initial drop due to drug leaving blood for tissues (e.g., fentanyl: 5 min).
t½ β: Slow final elimination (e.g., diazepam: 48h).
How to remember clearance and what’s its unit
The easy way to remember it is to remember its unit and its
(mL/min)
What is Steady-State?
point where the rate of drug administration equals the rate of elimination, resulting in a stable plasma concentration
Time to Reach Steady-State
Rule: Steady-state is achieved in 4–5 half-lives of continuous infusion or regular dosing.
A drug with a half-life of 6 hours reaches steady-state in ~24–30 hours.
