Pharmacology Cheat Sheet
Preparation, Delivery and Calculation
Clinical pharmacy skills for NEET-PG: enteric coating, revised ORS composition, paediatric dose formulae, therapeutic index, and renal dose adjustment.
MedNext Academy | 3 min read
Preparation, Delivery and Calculation
Clinical pharmacy skills for NEET-PG: enteric coating, revised ORS composition, paediatric dose formulae, therapeutic index, and renal dose adjustment.
Clinical pharmacy skills covering dosage forms, enteric coating, oral rehydration solution, paediatric dose formulae, and renal dose adjustment.
High-yield lines
- Enteric-coated tablets have a polymer coat insoluble at gastric pH below 3 but dissolving at duodenal pH above 6, protecting acid-labile or gastric-irritant drugs.
- The revised 2002 WHO oral rehydration solution has 75 mmol/L sodium, 75 mmol/L glucose, and a reduced osmolarity of 245 mOsm/L.
- ORS works through the sodium-glucose cotransporter, which continues to absorb sodium and water even in secretory diarrhoea.
- Ointments are greasy and occlusive, best for dry chronic lesions, while creams are oil-in-water and better for weeping lesions.
- Clark's rule calculates child dose as weight in kilograms divided by 70, times the adult dose.
- Young's rule applies to children 1 to 12 years as age divided by age plus 12, times the adult dose.
- Fried's rule for infants under 1 to 2 years is age in months divided by 150, times the adult dose.
- Therapeutic index equals TD50 divided by ED50, and narrow-index drugs like digoxin, warfarin, phenytoin, and lithium require monitoring.
- Drugs requiring renal dose adjustment include aminoglycosides, metformin, digoxin, methotrexate, vancomycin, acyclovir, and lithium.
- Bioavailability is the fraction of an administered dose reaching systemic circulation in active form.
- The old ORS formula had higher sodium of 90 mmol/L and osmolarity of 311 mOsm/L, revised because the reduced-osmolarity formula shortens diarrhoea.
- Enteric coating is used for drugs destroyed by acid and those that irritate the stomach.
- The reduced-osmolarity ORS lowers stool output and the need for unscheduled intravenous fluids.
- Semisolid dosage form choice depends on lesion character, with lotions and gels favoured for hairy or acute weeping areas.
Mapped competency codes
- PH2.1
- PH2.2
- PH2.3
- PH2.4
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This summary maps to PH16-clinical-pharmacy-skills.
Frequently Asked Questions
What is the composition of the revised 2002 ORS?
Sodium 75, potassium 20, chloride 65, citrate 10, and glucose 75 mmol/L, with an osmolarity of 245 mOsm/L.
How does Young's rule calculate paediatric dose?
Child dose equals age divided by age plus 12, multiplied by the adult dose, for children 1 to 12 years.
Why are drugs enteric-coated?
To protect acid-labile drugs and to prevent gastric irritation, since the coat dissolves only in the alkaline duodenum.
Which drugs need renal dose adjustment?
Aminoglycosides, metformin, digoxin, methotrexate, vancomycin, acyclovir, lithium, and most cephalosporins.
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