LIFE 106 – PHARMACOLOGY
Amy’s lecture
DRUGS
A drug is a chemical compound. A medicine contains a drug in a
suitable formulation.
The study of the actions of DRUGS on the body and the effects of body systems
on drugs
• discovering new medicines to help fight diseases
• improving the effectiveness of medicines
• reducing unwanted side effects of medicines
• understanding why individuals differ in the way they respond
to certain drugs, and why some others cause addiction
Ways drugs bind- ionic, hydrogen bonding, van der Waals,
hydrophobic interactions
Most drugs bind reversibly, irreversible binding is mainly confined to enzymes.
When you take a drug: Physiological exposure (enters the bloodstream) and
physiological clearance (detoxified and excreted).
Drugs bind to ENZYMES, RECEPTORS, ION CHANNELS,
CARRIERS/TRANSPORTERS AND DNA to affect the body.
After taking drugs, drugs must reach their target at a sufficient concentration to
produce desired results. This is dependent on ADME (Absorption, Distribution,
Metabolism and Excretion).
As proteins have a well-defined three-dimensional structure, receptors recognise
only a small number of molecules (ligands), all of which are similar in structure.
Histamine: an endogenous agonist. Binds to receptors
(histamine receptors) on stomach parietal cells and causes the release of
gastric acid
Ranitidine: An inverse agonist at the H2 receptor. Blocks the parietal cell
histamine
receptors. Therefore, an antacid.
However, mepyramine is an inverse agonist for another histamine receptor
subtype, H1 which controls smooth muscle contraction. The second receptor
subtype is the one which ranitidine is an antagonist for.
,Therefore, one histamine receptor controls stomach parietal cells while the other
receptor controls smooth muscles.
Nitonic acetylcholine receptor: Na+ influx at the neuromuscular junction.
Muscarinic acetylcholine receptor: K+ channel activation in cardiac cells
N-acetyl-para-aminophenol – Active ingredient for Panadol, paracetamol, and
acetaminophen.
Blockers – Ion channels
Inhibitors – Enzymes and transporters
Antagonist – Receptor.
Types/families of receptors: Ionotropic receptors[milliseconds] (ligand-gated
ion channels), metabotropic receptors[10-100ms] (G-coupled), kinase-linked
receptors and nuclear receptors (cytoplasmic).
Inverse agonist – This not only antagonizes the agonist but also induces an
opposite reaction. Antagonists only stop the effect of the antagonist, inverse
agonist does more than this.
2nd messenger effects of the G- protein pathway takes up to seconds.
Examples of inverse agonist drugs:
Nearly all H1 and H2 antihistamines (antagonists).
• Among the β-blockers, carvedilol and bucindolol demonstrate low levels of inverse
agonism.
• Several antipsychotic drugs (D2 receptors antagonist), antihypertensive (AT1
receptor
antagonists), antiserotoninergic drugs and opioid antagonists have significant
inverse agonistic
activity that to their therapeutic value.
Anticholinesterases (drug) – Inhibits cholinesterase (a molecule which prevents
acetylcholine from binding to its receptor) increasing the build-up of
acetylcholine.
Levodopa is a dopamine-like drug used to treat Parkinson’s disease by
increasing dopamine levels in the brain. Dopamine can’t be used because it
can’t cross the blood-brain barrier. L-DOPA is a pro-drug (precursor of a drug)
Prodrugs: to enable the drug to be formulated, enhance solubility, minimise
excretion, enhance the stability of the chemical, and target the drug to a specific
area.
, DOPA carboxylase which breaks down dopamine is inhibited by carbidopa.
Carbidopa is used in combination with L-DOPA to reduce levels of DOPA
carboxylase. Carbidopa doesn’t make it into the brain.
Fluoxetine blocks transporters. Fluoxetine is an SSRTI (Selective Serotonin
Reuptake Inhibitor)
• Serotonin is also known as 5-HT (5 – hydroxytryptamine)
• Role in modulating mood, cognition, reward, learning, memory, and numerous
physiological processes such as vomiting and vasoconstriction
• Serotonin binds to the 5-HT receptor to have its effect
Membrane potential
Hyperpolarization: Negative action potential. Occurs when sodium is taken into
the cell after depolarization has occurred. Then the cell returns to resting
potential.
Multiple sclerosis and Guillan-Barre syndrome: Damaged myelin sheath.
Lorna’s Neurone Lecture
Bipolar neurons (sensory): two extensions from the cell body
Unipolar neurons (mostly sensory neurones): on extensions from the cell body
Multipolar neurone (motor neurones): Multi extensions, longest neurones in the
body.
Glial cells are the connective tissue for the nervous system and help support the
neurons. They are also sites of tumours/infections.
Neuronal infections are reflected in the anatomy of the neuron.
The grey matter fully develops when a person reaches their 20s
Muscle Lecture
Types of smooth muscles:
Phasic and Tonic smooth muscles.
Phasic muscles are controlled by APs found in the stomach (peristalsis)
Tonic muscles are found in blood vessels and air pathways.
Fast and slow twitch muscles.
Cardiovascular system
