Pharmacology Cheat Sheet
Airways, Acid and Motility
Respiratory and GI pharmacology for NEET-PG: asthma LABA-ICS rule, theophylline toxicity, H. pylori triple therapy, and laxative and loperamide facts.
MedNext Academy | 3 min read
Airways, Acid and Motility
Respiratory and GI pharmacology for NEET-PG: asthma LABA-ICS rule, theophylline toxicity, H. pylori triple therapy, and laxative and loperamide facts.
Respiratory and gastrointestinal pharmacology covering asthma and COPD drugs, biologics, acid suppression, laxatives, and antidiarrhoeals.
High-yield lines
- Long-acting beta agonists must always be combined with an inhaled corticosteroid in asthma because monotherapy increases asthma-related mortality.
- The SMART regimen uses inhaled corticosteroid plus formoterol for both maintenance and reliever therapy, exploiting formoterol's fast onset.
- Theophylline has a narrow therapeutic window of 10 to 20 micrograms/mL, with toxicity progressing from vomiting to arrhythmias to seizures.
- Montelukast is particularly effective in aspirin-exacerbated respiratory disease where NSAIDs shunt arachidonic acid to leukotriene production.
- N-acetylcysteine acts as a mucolytic by breaking disulfide bonds and as the paracetamol overdose antidote by replenishing glutathione.
- Omalizumab is anti-IgE, mepolizumab and benralizumab target the IL-5 pathway, and dupilumab blocks IL-4 and IL-13.
- ACE inhibitor cough affects 10 to 15% of patients overall and up to 30 to 40% of South Asians, caused by bradykinin accumulation.
- Standard Helicobacter pylori triple therapy is a PPI with clarithromycin and amoxicillin, replacing amoxicillin with metronidazole in penicillin allergy.
- Eradication of H. pylori is confirmed 4 to 8 weeks after treatment using a urea breath test after stopping the PPI for 2 weeks.
- Polyethylene glycol (macrogol) is the drug of choice for chronic constipation and faecal impaction.
- Lactulose acts as both a laxative and a treatment for hepatic encephalopathy.
- Loperamide is avoided in children and in bloody diarrhoea, high fever, or invasive infection due to the risk of toxic megacolon and HUS in EHEC.
- Oral rehydration solution plus zinc is the WHO-recommended package for acute childhood diarrhoea.
- Mebeverine is the first-choice antispasmodic in irritable bowel syndrome because it lacks anticholinergic side effects.
Mapped competency codes
- PH1.32
- PH1.33
- PH1.34
Continue into the full chapter
This summary maps to PH8-respiratory-and-gi-pharmacology.
Frequently Asked Questions
Why must a LABA never be used alone in asthma?
LABA monotherapy increases asthma-related mortality, so it must always be combined with an inhaled corticosteroid.
What is the standard triple therapy for H. pylori?
A proton pump inhibitor plus clarithromycin and amoxicillin, with metronidazole replacing amoxicillin in penicillin allergy.
What causes ACE inhibitor cough?
Accumulation of bradykinin and substance P, sensitising bronchial C-fibres; it is more common in South Asians.
When should loperamide be avoided?
In children, and in anyone with bloody diarrhoea, high fever, or suspected invasive infection, due to toxic megacolon and HUS risk.
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