Define rational prescribing. Describe the P-drug concept and the essential medicines concept.

Definition and the WHO Criteria

The P-drug Concept

Define the problem and make a diagnosis → specify the therapeutic objective — what is this treatment meant to achieve? → Consider the available groups and compare them on efficacy, safety, suitability and cost → Choose a personal or "P-drug" for that condition — a small set of drugs you know thoroughly → Verify its suitability for this patient; the P-drug is a starting point, not a rule → Write the prescription, give information and instructions → monitor, and stop or change as needed

Essential Medicines

• Essential medicines are those that satisfy the priority health care needs of the population, selected with regard to public health relevance, evidence of efficacy and safety, and comparative cost-effectiveness
• They should be available at all times, in adequate amounts, in appropriate dosage forms, of assured quality, and at an affordable price
• The WHO Model List, first published in 1977 and revised every two years, and the National List of Essential Medicines (NLEM) of India, which also underpins price control through the Drugs (Prices Control) Order
• Advantages — better supply and procurement, lower cost, rational use, easier training and information, and improved quality assurance
• Related measures in India — generic prescribing, the Jan Aushadhi scheme supplying quality generics at low cost, and the ban on numerous irrational fixed-dose combinations

Common Irrationalities and How to Write a Prescription

• Irrational fixed-dose combinations — a persistent problem in India: multi-ingredient cough syrups, two NSAIDs together, antibiotic-steroid skin creams, and vitamin "tonics". Many have been banned, and the objection is that the components cannot be titrated separately and add toxicity without adding benefit
• Antibiotics for viral illness; injections where oral treatment would do; and polypharmacy in the elderly
• Parts of a prescription — prescriber and institution details; date; patient name, age, sex and weight; the superscription (Rx); the inscription (drug name, strength and dosage form); the subscription (quantity to dispense); the signa (directions to the patient); and the prescriber's signature and registration number
• Write the generic name, legibly and in capitals where necessary; the Medical Council regulations require generic prescribing in India
• Avoid dangerous abbreviations — write "units" not "U", "micrograms" not "µg", use a leading zero (0.5 mg) and never a trailing one (5.0 mg, which has been read as 50)

Applied Aspects

• The decision not to prescribe is a legitimate and often the best outcome, and explaining why takes less time than the consultation that follows an unnecessary prescription
• Review and stop — deprescribing is as much a skill as prescribing, and in the elderly it prevents more harm than any monitoring
• Cost is a clinical variable in India, where most medicine is paid for out of pocket; an unaffordable prescription is not taken, and the consultation has achieved nothing
• Explain, and check understanding — ask the patient to repeat the instructions; adherence depends more on this than on the choice of drug
• Beware promotional information; industry material is designed to persuade rather than inform, and independent sources should be preferred
• Report adverse reactions and irrational combinations, which is how the system corrects itself