The document discusses analgesics and their classification. It describes how analgesics are drugs that selectively relieve pain by acting in the central nervous system or on peripheral pain mechanisms. It classifies analgesics into two main categories - non-opioid analgesics such as NSAIDs that act primarily on peripheral mechanisms, and opioid analgesics such as morphine, codeine and fentanyl that act in the CNS. The document provides details on the mechanisms of action, uses and side effects of various classes of analgesics including NSAIDs, paracetamol, aspirin, morphine and other opioid agonists.

1. Dr. Ankit Bhardwaj
MBBS, MD (Gold Medalist)
Dept. of Pharmacology
Analgesics

2. Pain: its an unpleasant sensory and emotional experience
arising from actual or potential tissue damage.
Analgesic: drug that selectively relieves pain by acting in
CNS or on peripheral pain mechanism, without significantly
altering consciousness
Anti-inflammatory: drug or substance that reduces
inflammation (redness, swelling, and pain) in the body by
blocking inflammatory cytokines such as IL-1β, TNF-α, IL-6
and IL-15 and chemokines such as IL-8 and GRO-alpha
Introduction

3. 1. Non Opioid Analgesics
 Nonsteroidal anti-inflammatory (NSAIDs)/Non narcotic/aspirin like
analgesics
2. Opioid Analgesics
Narcotics/Morphine like analgesics
Classification

4. • Chemically diverse but most are organic acids.
• Grouped together as these drugs have common anti-inflammatory,
analgesic (pain reducing) and antipyretic effects at higher dose.
• Do not depress CNS – no physical dependence or abuse liability.
• Weaker analgesics than Morphine- except inflammatory pain
• Primarily act on peripheral pain mechanism, and also in CNS (raise
threshold)
Introduction to NSAIDs

5. Group Mechanism of action Drugs
Cox-1 Inhibitor
• Prostaglandin (PGs)
inhibitor
• Thromboxane A2 inhibitor
Aspirin, Ketoprofen Indomethacin,
Piroxicam and Sulindac
Cox-2 inhibitor
• Prostaglandins (PGE2 &
PGI2) inhibitors, decrease
sensitivity to bradykinin,
histamine serotonin and
other pain mediators
• Pro-inflammatory factors
inhibition (IL-1, IL-2, TNF-
α and oncogenes)
Preferential Nimesulide,
Diclofenac,
Aceclofenac,
Meloxicam, Etodolac
and Nabumetone
Selective Celecoxib, Etoricoxib
and Parecoxib,
Lumiracoxib
Classification

6. • 0steoarthritis, gout and rheumatoid arthritis
• Headache, myalgia and dysmenorrhea
Anti-inflammatory and
analgesics
• Decrease PGE2 synthesis in hypothalamusAntipyretic uses
• Inhibit platelet aggregation,
• formation of thrombi
CVS
• Acne, corns, Calluses and warts
• Arthritis Cream and sports rubs
External application
Pharmacological action

7. Aspirin (acetylsalicylic acid)
• Weak organic acids
• Fast oral absorption
• After short term administration t1/2 is 3-6hr,
long term use and or toxic overdose
increase t1/2 to 15-30hr

8. Adverse drug reaction

9. Confusion and Dizziness Precipitate asthma
Nephrotoxicity Bleeding risk CVS risk

10. Paracetamol (Acetaminophen)
• Derivative of P-aminophenol
• Inhibits COX-3 and prostaglandins biosynthesis in
CNS
• Minimal anti-inflammatory action
• Good oral absorption
• Toxicity Start at low dose (≤ 2g/day), serious hepatic
and renal toxicity seen at dose of 150mg/ kg or 10g
in adults
Antidote (overdose/toxicity)
N-acetylcysteine 150 mg/ kg

11. Opioid Analgesics

12. • Agonists Partial agonists Antagonists
• Codeine • Pentazocine • Naloxone
• Tramadol • Nalbuphine
• Hydrocodone • Buprenorphine
• Morphine • Butorphanol
• Oxycodone
• Hydromorphone
• Fentanyl
Classification

13. •Most analgesics effects
•ADR-euphoria, sedation, dependence, resp depressionµ receptors
•Analgesia
•Proconvulsantδ receptors
•Analgesia at spinal level
•Sedation, dysphoria, hallucinationsΚ receptors
• Not true opioid receptors
• Site of action for psychomimeticσ receptors
Opioid receptors

14. Opioid Agonists

15. MORPHINE
• Act specifically with opioid receptors present
in C.N.S and peripheral tissue, gut and
adrenal medulla and urinary bladder.
• Slow and erratic oral absorption
• Significant First pass metabolism
• Bioavailability – 20 - 40 %
• Sc, onset of action- 15 -20 min
• Peak effect – 1hr
• T1/2- 3-5hr
• Duration of action – 4-5hr

16. Analgesia
Euphoria, sedation , hypnosis
Respiratory depression
Depression of cough reflex
Miosis
Emesis
Excitatory effects
Pharmacological Actions

17. • HypotensionCVS
• Gastric motility-decreased
• Decreased intestinal secretions
GIT
• Decrease renal blood flow
• Antidiuretic effect
Renal function
• Inhibit release of GnRH
• Decrease blood levels of FSH,
LH, ACTH
Neuroendocrine
effects

18. Nausea
Vomiting
Dizziness, mental clouding
Drowsiness, Sedation
Constipation
Respiratory depression
Urinary retention
Adverse Drug Reactions

19. Analgesic
Anti tussive
Anti diarrheal
Codeine
• Naturally occurring opioid
• Weak analgesic compared to morphine
Therapeutic uses

20. Fentanyl
• A potent, synthetic opioid analgesics with
a rapid onset and short duration of action.
• Strong agonist at μ receptors.
• Use in epidural anesthesia
Sufentanil, alfentanil, and
remifentanil
• Synthetic opioid agonists related to
fentanyl.
• Sufentanil is more potent than
fentanyl.
• Majorly used for there analgesic and
sedative properties.

21. Methadone
• Synthetic Opioid
• Μediated by μ receptors
• Less euphoria
• Longer duration of action
Pharmacological Actions
Equianalgesic potency compared to morphine
Control withdrawal of opioid and heroin
Anti tussive

22. Partial Agonists and Mixed Agonist-Antagonist
Buprenorphine
• Partial agonist on μ receptor
• Opioid detoxification
• Less several withdrawal
• Treatment of opioid dependence
Pentazocine
• Agonist on κ receptors, weak antagonist
on μ and δ receptors
• Relieve moderate pain
• Less euphoria compared to morphine
• in higher doses cause hallucinations,
nightmares, dysphoria, tachycardia and
dizziness

23. Nalbuphine, Butorphanol
• Mixed opioid agonist-antagonist
• Limited role in treatment of chronic pain
• Butorphanol available as nasal formulation for severe
headaches, but associated with abuse

24. Other Analgesics
Tapentadol and Tramadol
• Centrally acting analgesics, agonist to μ opioid receptor
• Manage moderate to severe pain, both acute and chronic
pain

25. Thank you