Principles of pharacology Flashcards
what are exogenous ligands
pharmaceuticals and non-pharmaceuticals (what you might actually consider a drug)
what are endogenous ligands
hormones or neurotransmitters
drug receptor interactions
Receptor exist in at two states which are often referred to as a R and R*
A reversible equilibrium exists between the states
drug-receptor interactions - agonists
agonist mimic the action of an endogenous ligand
drug-receptor interactions - antagonist
antagonist bind to and stabalise R but do not mimic the biological response an endogenous ligand
affinity
High affinity - equilibrium favours R*
Lower affinity - equilibrium favours R
intrinsic efficacy
to elicit a biological response after binding to a receptor, a drug must have intrinsic efficacy
efficacy defines the size of the biological response that can be initiated when a drug binds to a receptor
potency
measurement of how much a drug it takes to elicit a biological response.
- product of affinity and intrinsic efficacy plus the downstream signalling cascade
what is the sympathetic and parasympathetic effect and receptors of the pupil
Sympathetic effect : dilation (contracts radial muscle)
receptor: a1
Parasympathetic effect: constriction (contracts sphincter muscle
receptor: M3
what is the sympathetic and parasympathetic effect and receptors of the airways
Sympathetic effect : relax
receptor: B2
Parasympathetic effect: contract
receptor: M3
what is the sympathetic and parasympathetic effect and receptors of the heart
Sympathetic effect : increase heart rate and force of contraction
receptor: B1
Parasympathetic effect: decrease rate of contraction
receptor: M2
what is the sympathetic and parasympathetic effect and receptors of the sweat glands
Sympathetic effect : localised generalised secretion
receptor: a1 and N3
where are beta adrenoreceptors present
on the cell surface of cells in the sinoatrial node, atrioventricular node and non-pacemaker cells of the heart
what is the effect of B1 adrenoreceptor activation Gas
include increased chronotropy, increased luistropy and increased inotropy
what are some indications for use of beta adrenoreceptor blockers include
- Rate control in atrial fibrillation – first-linetreatment (uncomplicated and comorbid withHFpEF)
- Secondary prevention in STEMI
- Management of stable angina – first-linetreatment
- Mitral stenosis – consideration
- HFrEF – first-line treatment
- Supraventricular tachycardia – recommended
- Ectopic beats
- Ventricular tachycardia –with/without an ICD
what is sotalol hydrochloride and what is its mechanism of action
used to treat certain types of heart rhythm disorders, particularly atrial fibrillation and ventricular arrhythmias.
mechanism of action: non-selective beta-adrenergic antagonist (beta blocker) with class III antiarrhythmic properties. works by blocking certain beta receptors in the heart leading to reduction in heart rate and the force of contraction.
what is pharmacokinetics
it involves the study of how the body interacts with a drug, encompassing its absorption, distribution, metabolism, and excretion (ADME)
what are factors influencing absorption
route of administration, drug formulation, physiological factors such as blood flow
where is the primary site of drug metabolism
the liver
what are factors affecting distribution
blood flow, capillary permeability, drug solubility, presence of binding proteins
what are the organs involved in excretion
the kidneys are the primary organs, through urine but the liver (via bile) and other routes such as sweat and saliva also contribute
ADME of sotalol
Absorption – Sotalol is almost entirely absorbed (oral) and escapes almost entirely from first-pass metabolism. Bioavailability is 90-100%.
* Distribution – Volume of distribution is 1.2-2.4 l kg-1
* Metabolism – Not metabolised
* Excretion – Renal clearance
what is EC50
represents the concentration of an agonist compound where 50% of its maximal agonistic effect is observed
what is the ID50
represents the dose required to kill half the members of a tested population after a specific duration of time
what is the IC50
represents the concentration of an antagonist compound where 50% of its maximal antagonist effect is observed
what is ED50
represents the minimum required dose to show desired activity of drug in half the members of a tested population after a specific duration of time
what is the order of drug trials
In vitro studies
Animal trials
Clinical trials
what is flecainide acetate
Flecainide acetate is an antiarrhythmic medication used to treat certain types of irregular heartbeats, particularly those arising from the atria (the upper chambers of the heart) and ventricles (the lower chambers of the heart). It belongs to the class Ic antiarrhythmic agents and works by inhibiting sodium channels, which helps stabilize the electrical activity of the heart
Flecainide acetate - ADME
- Absorption – Flecainide is almost entirely absorbed (oral) and escapes almost entirely from first-pass metabolism. Bioavailability is 90-95%
- Distribution – Volume of distribution is ~5.5 l kg-1
- Metabolism – CYP2D6* Excretion – Renal clearance
- Excretion – Renal clearance
