Dr Sk Sabir Rahaman – General Physician & Diabetologist in Kolkata

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert   When prescribing drugs, clinicians balance two opposing outcomes: therapeutic benefit vs toxicity . To quantify and compare drug safety, pharmacologists use Therapeutic Index (TI), Therapeutic Window (TW), and Margin of Safety (MOS). 🔹 1. Therapeutic Index (TI) 📌 Definition: The therapeutic index is a ratio comparing the dose that produces toxicity (or lethality in animals) to the dose that produces the desired therapeutic effect. 📐 Formula: In animals (preclinical): TI = LD₅₀ / ED₅₀ LD₅₀ = dose lethal to 50% of test animals ED₅₀ = dose effective in 50% of animals In humans (clinical): TI = TD₅₀ / ED₅₀ TD₅₀ = dose toxic to 50% of patients 📊 Interpretation: High TI → Safe drug (e.g., penicillin) Low TI → Narrow safety margin → requires monitoring (e...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert   Drugs differ not only in how much is needed to produce an effect but also in how much effect they can ultimately produce. These differences are explained by potency and efficacy . 🔹 1. Drug Potency 📌 Definition: Potency is the dose (or concentration) of a drug required to produce a given effect , usually expressed as EC₅₀ (the dose that gives 50% of maximum effect). A more potent drug achieves the same effect at a lower dose . Potency is dose efficiency , not drug strength. 📊 Example: Morphine (10 mg) and Pethidine (100 mg) give equivalent analgesia. ➡ Morphine is 10× more potent than Pethidine. 📈 Graphical Insight: On a log dose–response curve (DRC) : Leftward shift → higher potency Rightward shift → lower potency 👉 Clinical relevance: Potenc...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert When two or more drugs are given together, their effects may increase, decrease, or remain unchanged. Understanding these interactions is crucial to: Optimize therapy Enhance beneficial effects Prevent toxicity Design rational drug combinations 🚀 I. Increased Drug Response 1. Additive Effect 📌 Definition: The total effect equals the sum of the effects of each drug. Formula: Effect of A + B = Effect of A + Effect of B Example: Paracetamol + Ibuprofen → better pain relief (different mechanisms on pain pathways). ✅ Clinical Use: Multimodal pain therapy, antihypertensive combinations (ACE inhibitor + diuretic). 2. Potentiation (Supra-Additive Effect) 📌 Definition: One drug enhances the effect of another, even though it has no action on its own. Formula: Effect o...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert  One of the most fascinating aspects of pharmacology is that the same drug does not always act the same way in every person. Drug responses may vary in intensity (quantitative variation) or even in nature (qualitative variation). This variability arises from a combination of drug-related and patient-related factors. Additionally, when multiple drugs are prescribed together, drug interactions can further modify therapeutic outcomes. Let’s break this down systematically. 🧪 I. Drug-Related Factors 1. Route of Administration Quantitative variation: Dose and onset differ with route. Example: IV morphine (5–10 mg) works faster and at lower doses than oral morphine (30–60 mg). Qualitative variation: Same drug may act differently via different routes. Example: Magnesium s...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert Modern medicine is advancing at lightning speed—but with innovation comes skyrocketing costs. From high-priced biologics to costly cancer immunotherapies, healthcare systems worldwide are struggling with a common question: 👉 How do we deliver the best care without exhausting limited resources? This is where pharmacoeconomics comes into play. 📌 What is Pharmacoeconomics? Pharmacoeconomics is a specialized branch of health economics that evaluates both the costs (inputs) and the consequences (outcomes) of pharmaceutical products and healthcare interventions. It doesn’t just ask: Does the drug work? It also asks: Is it worth the money compared to alternatives? This field integrates: Clinical outcomes (effectiveness, safety) Economic costs (drug price, hospitalization, indirect c...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert Medicines save lives, ease suffering, and improve health outcomes. But when they are used irrationally , they can cause more harm than good. The World Health Organization (WHO) emphasizes the importance of the Rational Use of Medicines (RUM) to ensure patient safety, treatment effectiveness, and cost efficiency. In this blog, we’ll explore what RUM means, why it matters, and how healthcare professionals can practice it effectively. 📌 What is Rational Use of Medicines? According to WHO: “Rational use of medicines requires that patients receive medications appropriate to their clinical needs, in doses that meet their individual requirements, for an adequate period of time, and at the lowest cost to them and their community.” In simple words: it’s about prescribing the right medicine, in t...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert When we talk about medicines, two terms often create confusion – Generic Name (or Nonproprietary Name) and Generic Medicine . Though they sound similar, they represent two different but related concepts. Let’s break them down in a simple, clear way. 🔹 Generic Name / Nonproprietary Name Definition & Purpose A nonproprietary (generic) name is the official, internationally recognized name of a drug substance. It is accepted by competent scientific authorities (like USAN Council in the US or BAN in the UK ) and globally standardized through the WHO International Nonproprietary Name (INN) system . Once included in a pharmacopoeia, it becomes the official name used in prescriptions and medical literature. 👉 Example: Paracetamol is the generic name, while Crocin or Tylenol are brand nam...