Gastrointestinal
Acid, ulcers, nausea, bowels, and the liver — the drugs that keep digestion running from mouth to gut.
Foundations
How the gut makes acid, protects itself, and how the vomiting reflex and motility work.
Acid & Peptic Disease
PPIs, H2 blockers and antacids, peptic ulcers and reflux, and eradicating H. pylori.
Nausea & Motility
The vomiting pathways and their antiemetics, and the prokinetics that get the gut moving.
Bowel Habit
Laxatives for constipation, antidiarrhoeals, irritable bowel syndrome, and the gut microbiome.
Inflammatory Bowel Disease
Aminosalicylates, steroids and immunosuppressants — and the biologics that changed IBD care.
Liver, Biliary & Pancreas
Liver disease and GI bleeding, gallstones and bile acids, and pancreatic enzyme replacement.
How the Stomach Makes Acid — and Where the Drugs Act
The stomach deliberately fills itself with acid strong enough to dissolve metal, then protects its own wall from that acid. When this balance tips, you get ulcers and reflux — and almost every drug for them targets one point in a simple pathway. Learn how acid is made, and the whole acid-blocking section falls into place.
The Vomiting Reflex & Gut Motility: The Map Behind the Drugs
Why does one anti-sickness drug work brilliantly for chemotherapy but uselessly for travel sickness? Because vomiting can be triggered through several different receptors, and each drug blocks a different one. Learn this one map of the vomiting reflex, and you'll be able to pick the right antiemetic for the right cause — the single most useful idea in this whole section.
Proton Pump Inhibitors: The Most Powerful Acid Blockers
Omeprazole and its relatives are among the most prescribed drugs on earth, because they do one thing better than anything else: switch off stomach acid at its source. They heal ulcers, calm reflux, and protect the stomach — but their sheer effectiveness and popularity bring their own issues when they're taken forever. Here's how they work and when they're right.
H2 Blockers, Antacids & Alginates: The Gentler Acid Drugs
Not every bout of heartburn needs the full power of a PPI. Around it sit gentler, faster, or simpler options — a milder acid blocker, an instant neutraliser, and a clever raft that floats on the stomach to stop acid splashing up. Knowing where each fits is everyday practical pharmacology.
Peptic Ulcers & Reflux: Attack, Defence, and the Two Real Culprits
A peptic ulcer isn't just 'too much acid' — it's the balance between acid attacking the lining and mucus defending it, tipped the wrong way. And for most ulcers there are just two real causes to blame. Understanding attack-versus-defence tells you why we both suppress acid AND, in some cases, boost the stomach's own protection.
