📘 Medicinal Chemistry – Lecture 2: NSAIDs (Painkiller Drugs)

Easy Notes + Student-Friendly + High Engagement Style
By PharmaEasyNotes 💙

🎯 Lecture Objective

After this lecture, students will be able to:

✅ Understand how pain occurs
✅ Know how painkillers work
✅ Learn about NSAIDs
✅ Write proper exam answers

🔹 Introduction (Simple Way)

Think 🤔
You have a headache, toothache, or body pain…

What do you take first?
👉 A painkiller tablet 💊

These painkillers are called NSAIDs.

NSAIDs = Non-Steroidal Anti-Inflammatory Drugs

They:
✔️ Reduce pain
✔️ Reduce fever
✔️ Reduce swelling
✔️ Are not steroids

🔹 How Does Pain Occur?


Injury / Infection
        ↓
Release of Prostaglandins
        ↓
Pain + Swelling + Fever

👉 Prostaglandins are chemicals that cause pain and inflammation.

🔹 Mechanism of Action (Easy Flowchart)


NSAIDs → Block COX Enzyme
               ↓
     Prostaglandins ↓
               ↓
     Pain & Fever ↓

✔️ NSAIDs inhibit the COX enzyme
✔️ Less prostaglandin is formed
✔️ Pain and fever decrease

🔹 Types of COX Enzyme (Important ⭐)

Enzyme	Function
COX-1	Protects stomach lining
COX-2	Causes pain & inflammation

👉 Problem:
Old NSAIDs block both → stomach problems.

🔹 Classification (Flowchart Style)


NSAIDs
   |
-------------------------
|                       |
Non-Selective      Selective COX-2
(COX-1 & COX-2)     (Only COX-2)
|                       |
Aspirin          Celecoxib
Ibuprofen        Etoricoxib
Diclofenac

🔹 Important NSAIDs

✅ Aspirin

✔️ Oldest NSAID
✔️ Pain + fever + blood thinning

✅ Ibuprofen

✔️ Most commonly used
✔️ Fewer side effects

✅ Diclofenac

✔️ Strong pain relief
✔️ Used in joint pain

✅ Celecoxib

✔️ New generation drug
✔️ Less stomach irritation

🔹 Therapeutic Uses

NSAIDs are used in:

✅ Headache
✅ Toothache
✅ Arthritis
✅ Back pain
✅ Fever
✅ Muscle pain

🔹 Side Effects ⚠️

Common:

❗ Acidity
❗ Stomach pain
❗ Nausea

Serious:

❗ Ulcers
❗ Kidney damage
❗ Increased blood pressure

👉 Always take after food 🍽️

🔹 Structure–Activity Relationship (SAR – Easy)

Important features of NSAIDs:

✔️ Acidic group → Pain relief
✔️ Aromatic ring → Better binding
✔️ Lipophilic part → Good absorption

👉 Important for 2–3 marks in exams ⭐

🔹 Comparison Table (Quick Revision)

Drug	Strength	Side Effects
Aspirin	Medium	High acidity
Ibuprofen	Mild	Less
Diclofenac	Strong	More
Celecoxib	Medium	Less

📝 Exam-Oriented Points

✅ NSAIDs are non-steroidal drugs
✅ They inhibit COX enzyme
✅ Reduce prostaglandin synthesis
✅ Used as analgesic and antipyretic
✅ Cause gastric irritation

👉 Learn these for exams 💯

🌟 Memory Trick

👉 AID-C Formula

A – Aspirin
I – Ibuprofen
D – Diclofenac
C – Celecoxib

Easy to remember 😄

💬 Question for You:

Which painkiller do you use most?

A) Aspirin
B) Ibuprofen
C) Diclofenac
D) None

Comment below 👇
(Helps in interaction & learning 📈)

📌 Summary

✔️ NSAIDs are painkillers
✔️ They block COX enzyme
✔️ Reduce prostaglandins
✔️ Give pain relief
✔️ Main side effect = Acidity

❤️ Final Words

If you understand this lecture well,
you will never forget the NSAIDs chapter 💯

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