Pharmacology Flashcards
Drug
An active substance with a direct effect in the diagnosis, cure, mitigation, treatment or prevention of disease
Placebo
An inactive substance administered as though it’s a drug but which has no therapeutic effect
Homeopathy
Giving patients medicines that contain little to no medicine
Efficacy
How big is the max response
Potency
How big a dose for the desired outcome
Variability
The proportion of patients with desired outcomes
Selectivity
How selective a drug is to its molecular target
Safety
Proportion of patients with unwanted effects
Bioavailability
How much of an administered drug will reach circulation
Cost
How much does a course of it cost?
Explain Lock and Key
Most drugs are chemically inert but bind transiently to command and control modules
What is an agonist?
A drug that binds to a receptor to illicit a response
What is a partial agonist?
An agonist that cannot produce a maximal response even when occupying all receptors
How does a partial agonist act in the presence of a full agonist?
As a partial antagonist
What is an antagonist
A drug that binds to a receptor but produces no response and blocks agonists from binding
What does allosteric mean?
Relating to or changing the shape of a protein at a point other than the active site
What is physiological antagonism?
Two drugs at different receptors causing opposing physiological actions
What does label one show?
Superior Vena Cava
What does label two show?
Pulmonary Artery
What does label three show?
Pulmonary Vein
What does label four show?
Inferior Vena Cava
What does label five show?
Hepatic Vein
What does label six show?
Hepatic Artery
What does label seven show?
Hepatic Portal Vein
What does label eight show?
Renal Vein
What does label nine show?
Renal Artery
What does enteral mean?
Entering through the gut
What does suppository mean?
Entering through the rectum
What is a parenteral formulation?
An injectable drug
What does Lyophilized mean?
Freeze-dried
What is drug distribution?
The reversible transfer of a drug between the blood and extravascular tissue
Define Pharmacodynamics
What the drug does to the body
Define Pharmacokinetics
What the body does to the drug
Give the 6 main Parenteral routes
Subcutaneous, Intramuscular, Intravenous, Intraarterial, Intraosseous, Epidural
What does intraosseous mean? And what is the benefit of it?
Into bone marrow, non collapsible entry point to venous system
What is a topical formulation?
applied to the skin
Why do drugs need to dissolve to work?
To penetrate epithelial, endothelial and plasma membranes
What is ficks law?
Diffusion = ((Conc 1 - Conc 2) * area * Permeability) / Thickness
In a weak acid what will a PH increase cause?
Ionisation of target molecule
In a weak base what will decrease of PH cause?
Ionisation of target molecule
How do you calculate Bioavailability of oral drug from a Drug conc over time graph.
AUC (Oral) / AUC (IV) AUC = Area under curve
What is Bioavailability (F)?
Bioavailability (F) is the proportion of a drug that will reach circulation. It is between 1 and 0 and independent of dose.
How do you calculate Bioavailable dose?
Administered Dose * Bioavailability = Bioavailable Dose
What does Total body water include?
Blood volume + Interstitial volume + Intracellular volume
What does Extracellular volume include?
Blood volume + Interstitial Volume
What does Extravascular volume include?
Interstitial volume + Intracellular Volume
What is interstitial volume?
Fluid between cells
What is Intracellular volume?
Fluid within cells
What is typical blood volume?
5L
Define Bulk Flow
When a large amount of drug is injected into the bloodstream at once. It is distributed passively by passing through major organs.
What organs have good perfusion?
Liver, Lungs, Kidney, Brain, Heart
What organs have poor perfusion?
Fat, Bone, Muscle
What is Plasma protein binding?
When drugs bind to plasma protein so cannot cross membranes rendering them pharmacologically inactive.
What happens to plasma protein drug complexes when free plasma levels fall?
Bound drug is released from the complex
How do you calculate Volume of Distribution?
Vd = Drug dose / Plasma Conc
When can you not calculate Vd?
When drugs distributes unevenly
What is the blood brain barrier?
A collection of tight junction and astrocytes which prevent large / water soluble molecules entering the brain.
What is first pass metabolism?
When some oral drugs are metabolised before reaching circulation. This determines bioavailability.
Which organ does most metabolism?
The liver
Where is the CYP450 family of isozymes found?
Hepatocyte SER
What are the 2 stages of a conjunction reaction?
Inactivation and Solubilisation
What are the dangers of conjunction reactions?
May generate an active or toxic metabolite rather than an inactive one
What is a pro drug?
An inactive substance that is metabolised by the body after administration into an active drug
What drugs are excreted through the lungs?
Alcohol and inhaled anaesthetic
What molecules are excreted through biliary excretion?
Large metabolites (>500Da) and glucuronide conjugates
What are the 4 main stages of kidney excretion?
Throw away everything small, Take back anything still wanted, expel waste substances, excrete what is left
What is the afferent arteriole?
The arteriole that feeds blood into the glomerulus of the kidneys
What is the efferent arteriole
The arteriole that takes blood away from the glomerulus of the kidneys
What is Glomerular filtration?
The glomeruli passively filter 20 % of plasma on each pass, large molecules are not filtered into tubules, small molecules enter nephrons to be filtered
How do Lipophilic drugs pass through the kidneys?
Lipophilic drugs are able to diffuse back into
peritubular capillaries so are reabsorbed
How do some drug interactions effect absorption?
Some drugs can neutralise stomach PH which can alter gut motility.
How do some drug interactions effect distribution?
Drugs may compete for binding to plasma protein which will increase free concentrations.
How do some drug interactions effect Metabolism through induction?
Some drugs can increase gene expression of enzymes that metabolise it, drugs that are metabolised by the same enzyme will be metabolised quicker
How do some drug interactions effect metabolism through inhibition?
When a metabolic pathway cannot metabolise 2 drugs at the same rate as when they are alone.
How do some drug interactions effect excretion?
Drug excretion can be affected by PH in
kidney tubules
What is zero order elimination?
When a drug is eliminated at a constant rate
What is first order elimination?
When a proportion of a drug is eliminated per unit of time
What is Clearance?
The volume of blood from which the drug is cleared per unit of time.
What is continuous drug dosing?
a constant IV infusion which results in a steady state
what is a steady state?
When Plasma Conc (CPs) is constant
What is maintenance dosing?
When drugs are given at intervals to maintain an average Plasma Conc
What are loading doses?
A large first dose may be given to fill up the bodys Vd. This is followed by standard maintenance dosing or infusion.
How do you measure steady state?
Measured in half lives. The empty Vd will halve every half life.
What is the equation for Continuous IV infusion Rate of admin?
Rate of Admin = Rate of Elim = Clearance * CPss
What is the equation for Maintenance dosing??
(Dose * Bioavailability) / Dose interval = Cl * CPss
What is the equation for Loading Doses?
Loading dose * Bioavailability = Vd * CPss
What are the 3 branches of the ANS
Sympathetic NS, Parasympathetic NS and Enteric
Where are ganglions located in the Sympathetic NS
Towards the Spinal cord
Where are ganglions located in the parasympathetic NS
Towards the organ
How can the Sympathetic NS stimulate multiple organs at once
It can stimulate many post ganglionic neurons at once from the thoracic CNS region
What response does the Sympathetic NS create?
Fight or Flight
What response does the Parasympathetic NS create?
Rest and Digest
What neurotransmitters are used at Ganglions?
Acetylcholine
What receptors are used at the Ganglions?
Nicotinic recpetors (N1)
How many subunits make up a Nicotinic receptor?
5
How many ACh must bind to a Nicotinic receptor to open it?
2 ACh
Where are N2 receptors found
N2 (NM) are found at skeletal muscle junctions in the Som NS
What neurotransmitter is used at Parasympathetic NS post ganglionic nerves?
Acetylcholine
What receptors are used at Parasympathetic NS post ganglionic nerves on the target tissue?
Muscarinic AChR
What type of receptor is a Muscarinic AChR?
G-Protein coupled recpetor
What happens when ACh binds to a muscarinic AChR?
Ga protein will swap GDP for GTP. The Ga protein will dissociate and activate a downstream effector muscle.
What neurotransmitter do MOST Sympathetic NS post ganglionic nerves use?
Noradrenaline
What Receptor do MOST Sympathetic NS post ganglionic nerves use?
Adrenal receptors
What neurotransmitters and receptors do Sympathetic NS post ganglionic sweat gland nerves use?
Acetylcholine and Muscarinic receptors
What neurotransmitters and receptors do Sympathetic NS Adrenal medulla nerves use?
Acetylcholine and Nicotinic receptors
How do Adrenal medulla pathways differ to other Sympathetic NS pathways?
No ganglions on pathway
How do neurotransmitters re-enter the pre-synaptic vesicle.
Specific transporters for that neurotransmitter at reuptake sites
What is MAO and where is it found?
MAO (mono-amine oxidase) is a chemical that breaks down noradrenaline and is found in SNS pre synaptic neurons
How can a drug act as an agonist at a Muscarinic receptor?
Mimicking ACh and binding to M receptors
How can a drug act as an antagonist at a Muscarinic receptor?
Blocking ACh from binding to M receptors, this is often reversible but not always
How can you increase selectivity of Noradrenaline to Beta Adrenal receptors?
Adding groups to the N atom on Noradrenaline
What are the 2 types of Adrenoreceptors?
Alpha (a) and Beta (B)
Which Adrenoreceptor is Noradrenaline more effective towards?
a receptors
Which Adrenoreceptor is adrenaline more effective towards?
Effective against both but more selective to B receptors
Where are a1 adrenoreceptors found?
Blood vessels and Vascular smooth muscle
What does stimulation of a1 adrenoreceptors cause?
vasoconstriction which results in increase venous and arterial blood pressure
What do a2 receptors do and where are they found?
They are autoreceptors and prevent too much neurotransmitter being released. They are found on the pre-synaptic neuron
What do B1 adrenoreceptors do?
Increase HR and contraction force
What do B2 adrenoreceptors do?
Relax airways
