Biopharmaceutics Flashcards
Study of pharmacotechnical factors in drug products that can affect pharmacokinetics of drugs
Biopharmaceutics
2 layers of phospholipid between two surface layers of proteins
Lipid Bilayer/Unit Membrane Theory
Globular proteins embedded in a dynamic fluid, lipid bilayer matrix
Fluid Mosaic Model
Proteins are embedded and are used as receptors and for transport
Modified Fluid Mosaic Model
Semi-permeable membrane, Selective barrier, Drugs can transport via several mechanisms
Cell Membrane
Mechanism of drug movement across the cell membrane
Transport
bile acids/salt
deoxycholic acid/chenodeoxycholic acid
Dominant transport mechanism but the slowest/No energy required
Passive Diffusion
Drug must be small and should be lipid- soluble/Movement along a concentration gradient
Diffusion
_____acids exists more in a non-ionized form in a more acidic
Weak
High Ka
1 x 10^-2
Low Ka
1 x 10^-3
Ratio of solubility of a drug in oil to its solubility in water
Partition coefficient
K partition
lipid solubility/water solubility
greater the solubility of a substance/higher the permeability of the membrane to that particular substance
Higher partition coefficient
Cell membrane CHON w/ specific binding sites and can undergo conformational change
Carrier-mediated transport
Transport which requires energy, in which can move against the concentration gradient
Active Transport
Transport which doesn’t require energy, it move along the concentration gradient and has specific carriers
Facilitated diffusion
Fastest transport system
Active Transport
Specificity/Selectivity
Carrier-mediated transport
Drugs that are Subject to
competition/inhibition/antagonism
▸ Isoniazid and Vitamin B6
▸ Digoxin and quinidine
Saturability of Carrier-mediated transport
Zero or First Order of Kinetics
Rate of reaction is independent of the concentration of the drug remaining
Zero Order
Rate of reaction is dependent of the concentration of the drug remaining
First Order
Time it takes for the drug concentration to decrease by 50%
Half life
Movement through water-filled pores = channels
Convective Transport
Convective Transport: Charge of pore lining
allows movement of ions w/ charge opposite of pore lining
Convective Transport: Movement is by solvent drag
ions move along the same direction as water
Convective Transport: Movement along an electrochemical gradient
Takes into consideration the net charge and the concentration gradient ions with greater concentration gradient will be the one to move
Describes the movement of transport of large ions
Ion-Pair Transport
Examples of exogenous large cation
▹Quaternary NH4 Compound ▹ Mucin
Invagination of a cell membrane
Vesicular Transport
2 Types of Vesicular Transport
Endo and Exocytosis
Release of drug from dosage form or drug product
Liberation
Factors that are inherent in the drug product as a consequence of formulation and quality that is built in the product
Pharmacotechnical
Motion or change in rate
Kinesis
Fate of drugs in the body/What the body does to the drug?
Pharmacokinetics
Metabolism + Excretion
Elimination
Distribution + Eliminitation
Disposition
Biochemical & physiological effects of drugs/MOA
Pharmacodynamics
What the drug does to the body
Pharmacodynamics
Rate and extent of disappearance of drug from the site of administration or drug entry into systemic circulation
Absorption
Rate and extent of drug entry into systemic circulation
Bioavailability
Methods of determining bioavailability
● Drug Plasma Conc. vs. Time
● Cumulative urinary excretion data
Measure of the amount of the drug in the body that reflects the total amount of active drug
AUC
AUC is computed using ______
trapezoidal rule
Pharmaceutical equivalents that have similar bioavailability when given in the same molar dose and studied under similar experimental conditions
Bioequivalent Drug Product
Is established when two drug products have similar bioavailabilities/Measure the AUC ratio,Cmax Ratio,Tmax
Ratio
Bioequivalence
Similarity is established if each of the ratios fall within _
80% - 125% at 90%CI
Dissolution testing that includes comparison of the dissolution profiles of a generic and a comparator product in three media:
pH 1.2, 4.5, and 6.5
Process of dispensing a different brand
or unbranded drug product in place of the prescribed drug product
Generic Substitution
Drug products that contain the same therapeutic moiety but as different
salts, esters or complexes
Pharmaceutic Alternatives
Different dosage forms and strengths within a product line by a single manufacturer
Pharmaceutic Alternatives
Drug products with the same API, dosage form, dosage strength, mode of administration, standard quality
Pharmaceutic Equivalent
Process of dispensing a pharmaceutic alternative for the prescribed drug product
Pharmaceutic Substitution
Drug products containing different different API that are indicated for the same therapeutic or clinical objectives
Therapeutic alternatives
Drug products that can be used interchangeably in clinical practices
Therapeutic Equivalent
Process of dispensing a therapeutic alternative in place of prescribed drug product
Therapeutic Substitution
Process of drug movement from systemic circulation to different body compartments/Drug reaches the site of action
Distribution
Factor to be considered with drug distribution
▹ Cardiac Output
▹ Regional Blood Flow
Volume of blood pumped out by heart in 1 minute
Cardiac Output
Fraction of Cardiac Output that is delivered to specific tissues or organs
Regional Blood Flow
Areas with poor blood flow
Bones, fats
Areas with Highest perfusion
Brain, kidney, liver and heart
Distribution Parameters
Protein Binding
Volume Distribution
Large molecule whose distribution is restricted
Protein-bound drug
Type of drug that can readily cross the cell membrane and exert a pharmacologic effect
Free Drug
Blood protein that is dominant and binds with weak acids
Albumin: Blood Protein
Blood Protein that binds with Weak bases
Alpha 1-acid glycoprotein
Blood protein that binds with selective hormones
Globulin
Fatty Acids, Vitamin C, Salicylates, Sulphonamides, Barbiturates, Phenylbutazone, penicillins, tetracycline, probenecid; binds with what site ?
Albumins
Adenisine, Streptomycin , Chloramphenicol, Digitoxin, Coumarin binds with what blood protein?
Globulins, Alpha (1,2), Beta (1,2), gamma
Hypothetical or apparent volume of body fluid that is necessary to dissolve a given amount or dose of a drug to a concentration equal to that of plasma concentration
Volume of Distribution
Based on hypothesis and simplifying assumptions that describe biological systems in mathematical terms in order to predict drug action
Pharmacokinetic Model
A hypothetical volume that contains a certain drug concentration
Compartment
Type of compartment that the body is single compartment where certain volume remains constant; Instantaneous Distribution
One Compartment
Central/Peripheral
Two Compartment
Other name of Metabolism
Biotransformation
Converts drugs into other form
Metabolism
Drugs that are metabolised are converted into?
inactive/non toxic/water soluble compounds
Inactive parent drug that needs to be metabolized to active form
Prodrugs
Initial metabolism of a drug before it reaches the systemic circulation/ decreases oral bioavailability of a drug
First Pass Effect/Metabolism
Known as the 1st phase of drug metabolism
Functionalization Phase
Under Phase 1 Metabolism
Oxidation
Reduction
Hydrolysis
Enzymes under Phase 1: Oxidation
CYP Mediated/Independent
Substrate under CYP 1A2
Acetaminophen, theophylline, Caffeine
Substrate under CYPC19
Clopidogrel, PPIs
Substrate under CYP2C9
Warfarin, Phenytoin
Substrate under CYP2D6
Codeine, Antipsychotics
Substrate under CYP3A4,5,7 (superfamily)
More than 50% of drugs, CCBs,Macrolides, Azoles, Antifungal, Antihistamines
Enzymes under CYP Independent Oxidation
monoamine oxidase
Alcohol and aldehyde dehydrogenase
Phase 2 Drug Metabolism is also known as?
Conjugation reaction/ Synthetic Phase
Phase that involves the addition of a polar conjugate
Phase 2 Metabolism
Glucoronidation Enzyme
Glucoronosyl acyltransferase (GluCAT)
Acetylation Enzyme
N-acetyltransferase
Most common endogenous amine for conjugation with organic acids
Glycine conjugation
Enzymes localised in the liver and kidneys
Glutamine Conjugation
Reaction that reacts with electrophillic oxygen intermediates
Glutathione and mercapturic acid conjugation
Stimulate activity or production of enzymes
Enzyme induction
What happens if the substrate is a prodrug?
Increase in activity and risk of toxicity
What happens if the substrate has a toxic metabolite?
Increase in toxicity
What happens if the substrate is active with inactive metabolite?
Decrease d