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 1. Definition Medication reconciliation is a formal, systematic process of compiling the most accurate and complete list of all medications a patient is currently taking — including drug name, dose, frequency, and route — and comparing it with the physician’s active orders at every transition of care . 🔑 Goal: To ensure the patient receives the right medications at all times , preventing errors such as omissions, duplications, dosing mistakes, or harmful drug–drug interactions . 2. Purpose & Importance Prevents medication errors during care transitions (admission, transfer, discharge). Reduces adverse drug events (ADEs) , a major cause of hospital morbidity. Ensures continuity of care across providers, facilities, and home. Improves patient safety, adherence, and clinica...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert Definition: Pharmacodynamics (Greek pharmacon = drug, dynamis = power ) is the study of what the drug does to the body . It covers: Mechanism of action (MOA) at molecular, cellular, and systemic levels Intensity and nature of pharmacological effects Adverse drug reactions and therapeutic index Dose–response relationships 🔹 Core Concepts 1. Mechanism of Action (MOA) Drugs act by binding to specific targets : Receptors → β-adrenergic receptors (adrenaline) Ion channels → Ca²⁺ blockers (verapamil) Enzymes → Acetylcholinesterase inhibitors (neostigmine) Transporters → SSRIs (fluoxetine, blocks serotonin reuptake) 👉 Interaction may stimulate, inhibit, or modulate physiological functions. 🔹 Types of Drug Effects 1. Stimulation ↑ Activity of cells/tissues. ...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert   Drugs influence the body through two main mechanisms: Non-receptor mediated actions Receptor-mediated actions 🔹 I. Non–Receptor Mediated Mechanisms These don’t rely on binding to specific receptors. Instead, drugs act via physical, chemical, enzymatic, or structural properties . 1. Physical Actions Osmosis: Mannitol ↑ plasma osmolality → draws water out of brain/eye → used in cerebral edema, glaucoma. Adsorption: Activated charcoal binds toxins in the gut → prevents absorption in poisoning. Demulcents: Glycerin/syrup coat mucosa → soothe sore throat, pharyngitis. Radioactivity: Radioactive iodine (¹³¹I) destroys thyroid tissue in Graves’ disease, thyroid cancer. 2. Chemical Reactions Neutralization: Antacids (Al(OH)₃, Mg(OH)₂) neutralize gastric acid. ...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert   Receptors are specialized proteins on the cell membrane, cytoplasm, or nucleus. They bind ligands (drugs, hormones, neurotransmitters) to trigger biological responses. 👉 Drug + Receptor → Complex → Biological Effect There are 4 major receptor families , each differing in location, signaling, and speed of response . 🔹 1. Ligand-Gated Ion Channels (Ionotropic Receptors) Location: Cell membrane Response time: Milliseconds (very fast) Mechanism: Ligand binding → channel opens → ion flow (Na⁺, K⁺, Ca²⁺, Cl⁻) → depolarization or hyperpolarization Examples: Nicotinic ACh receptor (neuromuscular junction) GABAₐ receptor (Cl⁻ influx, target of benzodiazepines/barbiturates) Glutamate receptor (excitatory transmission) Clinical use: Benzodiazepines enhance GABAₐ → ...

By Dr. Sk Sabir Rahaman, MBBS , MD (Pharmacology), DFM(Family Medicine), FCFM, CCEBDM, CCLSD   📍 Specialist Family Physician | Consultant Pharmacologist | Lifestyle & Diabetes Expert   The dose–response relationship describes how the intensity or probability of a drug’s effect changes with increasing dose. It is a cornerstone of pharmacology and helps define: The minimum effective dose The therapeutic (optimal) dose The toxic or lethal dose ⚖️ Principle As drug dose increases, the effect increases — up to a maximum. Beyond this, higher doses give no further therapeutic benefit but may increase toxicity. 🔹 Types of Dose–Response Relationships 1. Graded Dose–Response Relationship Seen in a single individual . Shows a continuous, incremental response as dose increases. Useful for studying potency and efficacy . Plots : Dose vs Response → Rectangular hyperbola. Log Dose vs Response → Sigmoid (S-shaped curve) → easier comparison of dr...

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...