Pharmacology
Special Pharmacology
Special pharmacology for MBBS and NEET-PG: geriatric and paediatric prescribing, skin and eye drugs, pharmacogenomics, antiseptics and drug regulation, mapped to NMC codes.
MedNext Academy | 3 min read
Special Pharmacology
Special pharmacology for MBBS and NEET-PG: geriatric and paediatric prescribing, skin and eye drugs, pharmacogenomics, antiseptics and drug regulation, mapped to NMC codes.
This chapter covers special areas of pharmacology, including prescribing in the very young and the elderly, drugs for skin and eye disorders, essential medicines and rational prescribing, pharmacogenomics and pharmacoeconomics, antiseptics and disinfectants, and the regulatory and legal framework for medicines in India.
High-yield: Special Pharmacology
- Older patients have reduced renal clearance and greater sensitivity, so doses of many drugs are lowered and polypharmacy is minimised.
- In children, doses are calculated by body weight or surface area, and immature liver and kidney function alters drug handling.
- Topical corticosteroids are graded by potency, and prolonged use on the face or in children causes skin atrophy.
- Topical retinoids and benzoyl peroxide are mainstays of acne treatment; oral isotretinoin is highly teratogenic.
- Timolol eye drops lower intraocular pressure but can be absorbed systemically to cause bradycardia and bronchospasm.
- Mydriatics such as atropine and tropicamide dilate the pupil for examination, while pilocarpine constricts it.
- Essential medicines lists guide rational, cost-effective prescribing of the drugs most needed by a population.
- Fixed-dose combinations improve adherence but should be rational and evidence-based rather than irrational mixtures.
- Pharmacogenomics explains variable drug response, such as slow acetylators of isoniazid and thiopurine methyltransferase deficiency with azathioprine.
- Pharmacoeconomics compares the costs and outcomes of treatments to guide value-based decisions.
- Antiseptics are applied to living tissue while disinfectants are used on inanimate surfaces.
- Alcohol-based hand rubs and chlorhexidine are effective antiseptics for hand hygiene and skin preparation.
- Nutraceuticals and dietary supplements are widely used but need caution over interactions and quality.
- Drug regulation in India, including the Drugs and Cosmetics Act and schedules, governs how medicines are approved, sold and controlled.
Special pharmacology essentials
- **Geriatric prescribing:** Lower doses, reduced clearance, minimise polypharmacy.
- **Paediatric dosing:** By weight or surface area; immature organ function alters handling.
- **Antiseptic vs disinfectant:** Antiseptics for living tissue; disinfectants for surfaces.
- **Pharmacogenomics:** Genetic variation alters response, as with isoniazid acetylator status.
NMC competencies in this chapter
- **PH1.56:** Geriatric and paediatric pharmacology
- **PH1.57:** Drugs for skin disorders
- **PH1.58:** Drugs for ocular disorders
- **PH1.59:** Essential medicines, fixed-dose combinations and rational prescribing
- **PH1.60:** Pharmacogenomics and pharmacoeconomics
- **PH1.61:** Dietary supplements and nutraceuticals
- **PH1.62:** Antiseptics and disinfectants
- **PH1.63:** Drug regulations, acts and legal aspects
- **PH1.64:** Miscellaneous special topics in pharmacology
Frequently Asked Questions
Why do elderly patients need lower drug doses?
Ageing reduces renal and hepatic clearance and increases sensitivity, so standard doses can accumulate and cause toxicity, and polypharmacy adds interaction risk.
How are paediatric doses calculated?
Usually by body weight or body surface area, because immature liver and kidney function changes how children absorb, distribute and eliminate drugs.
What is the difference between an antiseptic and a disinfectant?
An antiseptic is applied to living tissue such as skin, while a disinfectant is used to decontaminate inanimate surfaces and instruments.
What does pharmacogenomics explain?
It explains why patients respond differently to the same drug based on genetic variation, such as slow acetylators of isoniazid or reduced thiopurine methyltransferase activity.
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