This document discusses opioid analgesics and antagonists. It focuses on morphine, describing it as the principal alkaloid in opium that is widely used today. The document outlines morphine's pharmacological actions in the central nervous system and peripherally, including analgesia, sedation, euphoria, and respiratory depression. It also discusses morphine's pharmacokinetics, uses for pain relief and other conditions, adverse effects like respiratory depression, and contraindications. Treatment for acute morphine poisoning includes positive pressure respiration, maintaining blood pressure, gastric lavage, and using the antidote naloxone.

1. Opioid Analgesics
and Antagonists
Presented by:
Mr.Preetham U G
2nd year ATOT
Allied Health Sciences

2. .
 Analgesic: A drug that selectively relives pain by acting in
the CNS or on peripheral pain mechanisms, without
significantly altering consciousness.
 Opium: A dark brown material obtained from poppy
plant(papaver somniferum)

3. CLASSIFICATION

4. Mechanism of action:

5. MORPHINE
 Morphine is the principal alkaloid in opium and is widely used till today.
 It is described as a prototype drug.
 Pharmacological action:
1. CNS actions:
- Analgesia
-Sedation
-Euphoria
-Respiratory depression
-Cough suppression
-Temperature regulation
-Vasomotor center

6. .
2) Neuro-endocrine actions
-as decrease in FSH, LH, ACTH,
3) Peripheral actions
a)CVS-vasodilatation
-histamine release
b)GIT-decrease in GI secretions
c)Other smooth muscles-spasm of sphincter of
oddi

7. Pharmacokinetics:
• Oral absorption of morphine is unreliable because of high
and variable first pass metabolism.
• Oral bioavailability is nearly 14th of parenterally
administered drug.
• Morphine freely crosses placenta and can affect the foetus
• More than the mother.

8. Uses:
• As analgesic – as postoperative pain, burn, cancer pain,
myocardial infarction, renal and biliary colic.
-epidural analgsia
• Preanesthetic medication
• Acute left ventricular failure/acute pulmonary edema
• Diarrhoea
• Dry cough and irritating cough
• Shivering
Sedative-in the presence of pain

9. ADVERSE EFFECTS:
• Apnoea of newborn
• Respiratory depression
• Blurring of vision
• Urinary retention
• BP may fall in hypovolaemic patient
• Acute morphine poisoning
• It has high degree of tolerance and dependence so it is used
as drug abuse

10. Contraindications:
• Avoid opioids in patients with respiratory
insufficiency,COPD.
• Head injury
• Hypovolaemic shock
• Pregnancy
• Renal and hepatic dysfunction

11. Acute morphine poisoning:
• Poisoning may be accidental, suicidal or homicidal.
• Signs and symptoms
-pin-point pupils, hypotension, shock,
hypothermia, coma, and death due to respiratory failure and
pulmonary oedema.
• Treatment:
1. Positive pressure respiration
2. Maintenance of BP.
3. Gastric lavage with Potassium permanganate to remove
unabsorbed drug
4. Specific antidote is Naloxone-0.4-0.8 mg IV repeated every
10-15 min.

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