PHARMACOLOGY NEED TO KNOW Flashcards
(40 cards)
Define Agonist
= binds to receptor and brings about physiological response
Define Receptor
= a molecular structure or site on the surface or interior of a cell that binds with substances
Define Antagonist
= bind to receptors, however, have no efficacy (don’t activate receptors)
4 Receptor Types
- Ligand-gated Receptors: Inotropic Receptors
- G-Protein Coupled Receptors: Beta-Adrenoreceptor
- Kinase-Linked Receptor
- Nuclear Receptors
Describe Inotropic Receptors: Nicotinic Receptors
- 5 transmembrane units
- endogenous agonist is Acetylcholine (Ach)
- 2 molecules of Ach bind, opening Na channels
- ions flow down concentration gradient
Describe Beta-Adrenoreceptors
- 7 transmembrane units
- endogenous agonist is adrenaline
- agonist binding activates G-Protein
Define EC50
= Effective Concentration Value
- the concentration of a drug that gives half-maximal response
- used as a measure of potency
Define Potency
= amount of drug needed to produce a given effect
Define Efficacy
= maximal effect that a drug produces irrespective of dose/concentration
Define ADME
A= Absorption D= Distribution M= Metabolism E= Excretion
3 Pros & 3 Cons of Oral Administration
Pros:
- convenient
- 75% absorbed in 1-3 hours
- slow release formulation
Cons:
- some drugs not well absorbed
- influence of foods on absorption
- affected by first-pass metabolism in liver
3 Pros & 2 Cons of Rectal Administration
Pros:
- avoids first pass metabolism
- reduces vomiting/nausea
- good when patient is unconsciousness
Cons:
- inconvenient
- absorption often incomplete
Metabolism by Liver Hepatocytes
- drugs taken orally enter the liver via the hepatic portal vein
- concentration of a drug is greatly reduced by the liver before it reaches systemic circulation
Injections to Avoid First Pass Metabolism
3 Pros & 3 Cons
intramuscular = i.m. intravenous = i.v. subcutaneous = s.c. intradermal = i.d.
Pros:
- rapid onset compared to oral (i.v. > i.m. > s.c.)
- drugs are not broken down by acid/enzymes as in the gut
- first pass metabolism in liver is less of a problem
Cons:
- less convenient (needs skilled person)
- risk of infection
- more toxicities (higher peak blood levels)
Non-Needled Sublingual Administration
- good vascularisation
- avoids first pass metabolism
- absorbed rapidly
Non-Needled Topical Administration
- localised administration
- reduced systemic toxicity
Enzymatic Reactions
Phase 1 Reactions:
- Oxidation (Cytochrome P450)
- Hydrolysis (esterases)
- Reduction (reductases)
Phase 11 Reactions: Add water soluble moiety to drug
- sulfate
- acetate
Describe Phase 1 Reactions - Oxidation (Cytochrome P450)
- enzymes that metabolise prescribed drugs
- cytochrome P450 can be inhibited or induced by drugs which affects distribution of drugs in the body
List the 4 Drugs of Hypertensives
- Diuretics
- Vasodilators
- Calcium Channel Blockers
- Betablockers
List the 4 Drugs of Heart Failure
- Positive Inotropic Agents: Digoxin/Digitalis
- Vasodilators: ACE Inhibitors, nitrates
- Diuretics
- Beta Blockers
Describe Calcium Channel Blockers (Nifedipine and Verapamil)
- inhibit Ca ion movement into vascular and cardiac muscle
- causes peripheral and coronary vasodilation
- decreases heart rate and contractility
Describe Beta Blockers
- act on heart tissue
- reduce heart rate
- reduce ventricular contractility
Describe Positive Inotropic Agents: Digoxin/Digitalis
- blocks Na/K pump which impairs Ca ion transfer OUT of membrane
- this increased build up of Ca ions leads to a stronger, fuller, less-erratic heart beat
- increased cardiac output
Describe Vasodilators: ACE Inhibitors
- dilated artery = lower blood pressure
- coronary arteries open
- ACE inhibitors stop angiotensin production
- lower blood pressure and increased blood to heart