Intro to pharmacology Flashcards
(51 cards)
What is pharmacology
the use, effects and modes of action of drugs to modify disease.
PharmacoKINetics
what the body does to the drug- absorbtion, distribution, metabolism, elimination
elements of a Pharmokinetic profile
PharmacoDynamics
What the drug does to the body- Effect, response (toxicity/effectiveness)
Therapeutic effect vs side effect
Fine balance on correct dosage
3 routes of administration
Enteral (GI), PARenteral (parallel), Topical (direct application)
First pass metabolism
when drugs have to pass through GI tract casues loss of activity. Esp enteral route.
Enteral (GI) routes
Sublingual, Oral, Rectal
SIM VPM TAC
Parenteral routes x9
Subcutaneuos, inhalation, Intra - muscular,vascular,peritoneal,meduallary, thecal,articular, cardiac MVPMTAC
4 biochemical factors can affect the choice of adminstration route
- Pysical and chem properties ( gas, liquid, solid, ph etc).
- Site of action- aproachable/non approachable
- Rate and extent of absorption fromdifferent routes
- Effect of digeston and 1st pass metabolism
3 Clinical factors effecting route of administration
- Rapidity of response - routine or emergency
- Accuracy of dosage
- Condition of patient - unconscious, vomit
PharmacoKINetics ADME
Absorption - 2 mechanisms
Bulk flow ( via bld/lymph or CSF)
Diffusion (Molecular transfer)
the drug must pass across at least 1 membrane
Absorption - diffusion x 5
- Simple dif through lipid layer (high to low conc / no energy) - lipid soluble drugs (non polar) Aspirin
- Diffusion through aquaporin channels in lipid layer
- facilitated transport using solute carriers
- endocytosis (cell engulfs the drug - for large molecules)
- Active transport (low to high conc - ATP + carrier protein)
SAFEA
bold = most important
What can effect absporption x6
- Food
- Other medications
- drug formulation ( coatings),
- comorbidities,
- first pass metabolism,
- chemical stability
PharmacoKINetics
Distribution
reversible transfer of drug between circulation and tissues.
What can effect distribution
What can effect distribution x5
membrane permeability, lipophilicity, ionisation, drug structure, plasma protein binding, volume of distribution.
Plasma protein binding
Drug bind to proteins and only the free (unbound) drug is active and can leave the blood to reach tissues.
High plasma protein binding:
Less free drug available → slower distribution.
Acts like a drug reservoir → longer duration of action.
Low binding → More free drug → faster distribution and possibly more effect.
Volume of distribution
how extensively a drug spreads into body tissues compared to the plasma (blood).
High Vd → Drug leaves the bloodstream and goes into tissues (e.g., fat, muscle).
Low Vd → Drug stays mostly in the blood/plasma.
Which are the 2 main organs where drugs are metabolised
Liver and small intestine
Whats the pupose of drug metabolism
Detoxification & elimination
Inactiviation
activiation Codeine-Morphine,
lipophilic to hydrophilic compounds.
hepatic metabolism phase 1
Preconjugation reactions
* to make the drug more h20 soluble
* Oxidation, hydrolysis, reduction
* The liver adds or exposes a functional group (like –OH, –NH₂, –SH)
* Makes the molecule slightly more polar (water-friendly)
* CYP450 enzymes used
hepatic metabolism phase2
Conjugation Reactions
- The liver adds a big, water-loving molecule to the drug (or its Phase I metabolite)
- Glucuronidation, acetlation, methylationan, suphation.
- This increases water solubility and helps the body eliminate it (mainly via kidneys)
Enzyme used at phase 1 metabolism
Cytochrome P450 enzymes (CYP450)
Enzyme used at phase 2 metabolism
Transferases (e.g., UGTs for glucuronidation, SULTs for sulfation)
What can first pass metabolism effect
reduce bioavailabilty and half life.
