Pharmacology - Blog Posts

Pharmacology is going to kill me. I have an exam on Thursday that I know I'm not going to do the greatest on since I've just been very unmotivated the last 2 weeks. Now that I'm feeling good again I'm kicking myself for not trying harder 😭 how am I going to memorize all these drugs?!

I tried to make two oddly specific warning signs.

Revision of some notes on the grapefruit juice effect on drugs, because pulling up a wikipedia page in a room of doctors would be a mistake

Look at that nasty grapefruit too

It is my first time using hex graph paper in a good while so I’m making it a new “chemicals of interest” notebook.

I think it looks passable so far, though sometimes I include the hydrogens because it’s fun to draw on this.

Metabolites of Caffeine (at least to the best of my referencing ability)

Cytochrome P450 Inducers & Inhibitors

The main ones can be remembered using "CRAP GPs spend all day on SICKFACES.COM".

Cytochrome P450 Inducers

These induce CYP450 activity, and thus reduce the concentration of drugs which are metabolised by this system.

Carbemazepine Rifampicin Alcohol (chronic use) Phenytoin Griseofulvin Phenobarbitone Sulphonylureas, St John's Wort, Smoking

Also topiramate.

Cytochrome P450 Inhibitors

These inhibit CYP450 enzyme activity and thus increase the concentration of drugs which are metabolised by this system.

Sodium valproate Isoniazid Cimetidine Ketoconazole Fluconazole Alcohol (acute use), Amiodarone, Allopurinol Chloramphenicol Erythromycin Sulfonamides, SSRIs Ciprofloxacin Omeprazole Metronidazole

Also grapefruit, cranberry juice, diltiazem, verapamil, clarithromycin.

Common Interactions

Medications which commonly interact with CYP450 inhibitors and inducers are:

Warfarin

Phenytoin

Combined Oral Contraceptive Pill (COCP)

Theophylline

Corticosteroids

Tricyclic antidepressants

Statins

Lamotrigine

Midazolam

Causes of drug-induced lupus

SHIP

Sulfasalazine & Sulfonamide Hydralazine Isoniazid Procainamide & Phenytoin

This is by no means a definitive list (they are many!) but these are some of the most common causes.

Common ototoxic medications

"FAV Q&A"

Furosemide (and other loop diuretics) Aminoglycosides Vancomycin Quinine Aspirin

Basic pharmacology of neuromuscular junction

ACh acts on N2 receptors (ligand-gated Na+/K+ receptors)

Block Na+ channels that propagate nerve impulse - local anaesthetics (lidocaine), tetrodotoxin

Inhibit ACh release - tetanus toxin, botulinum toxin

Competitive antagonists - vecuronium

N2 agonists - suxamethonium

Flaccid paralysis

Only cleared by plasma cholinesterase

Reversible anticholinesterases - edrophonium, neostigmine, physostigmine

Block activity of AChE

Diagnose and treat myasthenia gravis and treat glaucoma respectively

Irreversible anticholinesterases - organophosphates (pesticides, nerve gases)

Long-lived flaccid paralysis

Treat with pralidoxime within 10 minutes - cleaves OP-AChE complex

Management of acute MI

Reduce anginal pain

Morphine (+ anti-emetic)

Oxygen

Nitrate

Initiate reperfusion

Anti-platelet (aspirin, clopidogrel)

Thrombolytic (rtPA)

Primary angioplasty (PTCA)

Anticoagulant (heparin)

Protect myocardium

Beta-blocker

ACE inhibitor

Secondary prevention

Aspirin

Lipid-lowering (statin)

Lifestyle

Helpful mnemonic foe MI treatment.