intro to pharm Flashcards
What is pharmacology?
The branch of medicine and biology concerned with the study of drug action
What does clinical pharmacology focus on?
Focuses on the application of pharmacological principles and methods in the medical clinic and towards patient care and outcomes
What is toxicology?
It is the study of the adverse effects, molecular targets, and characterisation of drugs or any chemical substance in excess
What are drugs?
They are substances that selectively interact with endogenous molecules to modify the functions of cells, physiological systems and living organisms
What can are considered pharmaceuticals or medicines ?
Used in the treatment or prevention of disease
What are the 2 types of drugs?
- Agonists| 2. Antagonists
What do agonist drugs do?
They bind to and activate receptors to produce a biological response
What do Antagonists drugs do?
They block or dampens a biological response by binding to and blocking a receptor rather than activating it like an agonist
What is the main difference between Antagonists and agonist drugs?
Agonist drugs activate receptors| Antagonist block receptors
What are drugs usually classified by?
By what they disease they are used to treat
Name 4 classifications drugs can fall in?
Drugs used :
1. In chemotherapy (e.g. antibiotics- not always cancer)
2. To replace deficiencies of endogenous substances (insulin)
3. To change the regulation of peripheral physiological systems (vasoconstrictors)
4. to alter the function of the CNS (e.g.general anaesthetics) or PNS (e.g. local anaesthetics)
Name the 2 main branches of pharmacology
- Pharmacokinetics| 2. Pharmacodynamics
What is Pharmacokinetics (PK) the study of?
How a drug is absorbed, distributed, metabolised or excreted (ADME).
What is Pharmacodynamics (PD) the study of?
How well the targets (e.g. receptors, ion channels, enzymes, and immune system components) respond to a drug.
How do drugs work?
By binding to receptors
Do drugs activate or inhibit receptors?
The do both| They can cause either the activation or inhibition of a regular body process to give a biological response.
Define Pharmacodynamics
The study of the physiological effects of drugs on the body and the mechanisms of drug action and the relationship between drug concentration and effect
What 4 factors about a drug are studied in Pharmacodynamics?
- Mechanisms of drug action
- Time course of drug effects
- Adverse drug affects
- Drug-drug interactions (existing drugs effect what u gonna give? prescribed/ recreational)
What do Sedative-hypnotics do?
They depress the function of the CNS
What does the ED50 value of a drug measure?
The dose required to produce 50% of maximum response
What does potency mean in terms of drugs?
The amount of drug necessary to produce a certain effect
How are differences in drug potency evaluated?
By comparing the ED50 values
Does the most potent drug have a high or low ED50 value?
Low
What does efficacy mean in terms of drugs?
The maximum response that a given drug will produce irrespective of dose (Emax)
What does the Emax value measure?
the maximum response that a given drug will produce, irrespective of dose
How are differences in efficacy measured?
By comparing Emax values
Define pain threshold
The magnitude of pain stimulus required to elicit a response
Name 4 potential substances drugs can target in mammalian cells
- Receptors -for neurotransmitters and hormones
- Ion channels-Na+ and Ca2
- Enzymes e.g. angiotensin converting enzyme (ACE) andcyclo-oxygenase (COX)
- Transporters (carrier molecules) e.g for mono amine neurotransmitters
What are receptors?
Receptors are the sensing elements in the system of chemical communications that coordinates the function of all the different cells in the body.
The chemical messengers are various hormones, transmitters another mediators
Give some examples of receptors drugs can target
- Receptor operated ion channels
- G-protein coupled receptors
- Kinase-linked receptors
- Nuclear receptors
What effect can an agonist drug give when administrated to target a receptor?
- Ion channels can open/close
- Enzymes can be activated/ inhibited
- Ion channels can be modulated
- DNA transcription
What are ion channels?
Ion channels are essentially gateways in cell membranes| Selectively allow the passage of particular ions
What are the 2 important ion channel we need to know?
- ligand-gated channels| 2. voltage-gated channels
Give an example of a ligand gated ion channel
Nicotinic acetylcholine receptor
What activates Nicotinic acetylcholine receptors?
the binding of two acetylcholine molecules
What does the Nicotinic acetylcholine receptor do?
As a ligand gated ion channel it permits the movement of positively charged ions from the synaptic cleft into the cytoplasm
What do agonist drugs do when they target ion channels?
Diffusion is blocked
What do antagonist drugs do when they target ion channels?
They increase or decrease the opening probability
How do drugs that target enzymes work?
The drug molecule is often a substrate analogue that acts as a competitive inhibitor of the enzyme OR the binding is irreversible and non-competitive
Give an example of a drug molecule that acts as a competitive inhibitor of enzymes
Captopril, acting on ACE
Give an example of a drug molecule that acts as a competitive inhibitor of enzymes
aspirin, acting on COX
How do ions and small organic molecules cross cell membranes?
- Channels (Ion channes| 2. Transport proteins
Why do some ions and organic molecules need to used transport proteins?
Because the permeating molecules are often too polar (i.e. insufficiently lipid soluble) to penetrate lipid membranes on their own. so are actively transported e.g. dopamine transporter
Define Pharmacokinetics
The determination of the fate of substances administered externally to a living organism
What mechanisms do we check to describe how the nodes affected by a specific drug?
Absorption: the passage of a drug from its site of administration into the plasma
Distribution through the blood plasma and different body tissues
Metabolism: the chemical changes of the substance in the body
Excretion or elimination of the substance or the products of its metabolism
What us the acronym we use to remember how the 4 stages if deposition is divided?
ADME -Absorption Distribution Metabolism Excretion
What is drug interaction?
Is a situation in where a substance affects the activity of a drug when both are administered together
Name the 6 ways drugs can be administered into the body?
- Oral or rectal2. Percutaneous 3. Intravenous 4. Intramuscular 5. Intrathecal 6. Inhalation
Name the 5 ways drugs can be eliminated from the body
- Urine2. Faeces 3. Milk4. Sweat glands5. Expired air
What do you focus on in Pharmacokinetics?
usually focuses on concentrations of drug in blood plasma
What 2 assumptions are made in Pharmacokinetics when looking at drug concentration in blood plasma ?
- The plasma concentration bears a precise relation to the concentration of drug in the immediate environment of its target
- The drug response depends only on the concentration of the drug in the immediate environment of its target
what 2 things make drugs differ?
in relationship between dose and degree of CNS depression
what is a narrow margin of safety?
not much increase in dose= dangerous effects
example of narrow and wide marginal safety?
narrow= alcohol and barbiturates (alcohol poising, barb= chemical execution)
wide= Benzodiazepines (e.g.diazepam)
negative effect of high doses?
drug will depress respiratory and vasomotor centres (respiratory arrest)
what does a low does need to activate CNS depression?
higher doses
steps leading to CNS depression?
sedation> hypnosis> anaesthesia> coma
what are the responses of biological effect?
*Quantity or proportion– frequency of seizures– mortality rate (%)
* Continuous measurement– blood pressure
* Ordered descriptive category– severity of lesion
why do codeine and morphine have the same % of pain threshold elevation? (similar efficacy)
codeine metabolises into morphine, so enough codeine causes same reaction
full agonist vs partial agonist?
full= large stimulus to cellular signalling machinery> large effect
partial= small stim to cellular signalling machinery> small effect
possible effects of drug-drug interaction
- dec action of drugs
- inc action of drugs
- cause adverse effects
Main routes of drug administration and elimination
how do antihistamines work?
bind to histamine receptors: prev bonding. stops puffiness happening
