Good prescribing is a skill with a method. The WHO Guide to Good Prescribing turns it into a repeatable sequence built around your P-drug — and that six-step process below is the backbone of the whole topic.
1. Rational use of drugs (RUD)
WHO definition: patients receive medications appropriate to their clinical needs, in doses that meet their own requirements, for an adequate duration, and at the lowest cost to them and their community.
In short — the right drug, right patient, right dose, right route, right time, right duration, right cost (after a correct diagnosis). Irrational prescribing means polypharmacy, antibiotic/injection overuse, and wrong or ineffective drugs.
2. The P-drug (personal drug)
A P-drug is the drug a prescriber chooses to use regularly for a given condition and becomes thoroughly familiar with. You select it once, against four criteria:
| Criterion | Question to ask |
|---|---|
| Efficacy | Does it actually work for this condition? |
| Safety | Adverse effects and contraindications? |
| Suitability | Patient factors — age, pregnancy, comorbidity, interactions. |
| Cost | Affordable for the patient and the system? |
At step 3 you check your standard P-drug still fits this particular patient.
3. Essential medicines & the NLEM
- Essential medicines (WHO): those that satisfy the priority healthcare needs of the population — selected by disease prevalence, evidence of efficacy & safety, and comparative cost-effectiveness.
- WHO Model List of Essential Medicines — first published 1977, updated every 2 years.
- National List of Essential Medicines (NLEM), India — NLEM 2022 (~384 medicines); it is the basis for price control (DPCO / NPPA), procurement and training.
4. Prescription & audit
- Parts of a prescription: superscription (Rx), inscription (the drug), subscription (dispensing instructions), signa (directions for the patient), and prescriber details.
- WHO / INRUD prescribing indicators: average number of drugs per encounter, % prescribed generically, % with an antibiotic, % with an injection, and % from the essential medicines list.
- Generic prescribing and rational fixed-dose combinations are encouraged.
Exam tip: remember P-drug selection as E-S-S-C — Efficacy, Safety, Suitability, Cost — and the six-step flow (problem → objective → P-drug → prescribe → inform → monitor). For essential medicines quote WHO EML 1977 (2-yearly) and NLEM India 2022 (~384).
Rational prescribing isn’t guesswork — it’s a defined method anchored to your P-drug and the essential-medicines concept. Learn the six steps and the four criteria, and you can justify every prescription you write.