L17- Analgesics (2)

Question 1

What are the two forms of dependence?

Answer 1

• Psychological- taking drug for its pleasurable effects

* Physical- take drug to stop unpleasant withdrawal symptoms

Question 2

How are the opioids administered?

Answer 2

• Orally or by injection
• Bupreporphine sublingually
• Fentanyl and sufentanil given intrathecally during surgery

Question 3

What are the pharmakokinetic aspects of morphine?

Answer 3

• Glucuronidation occurs in the liver
• Glucuronides excreted in urine
• Plasma half life of morphine is 3-6 hours in adults, longer in neonates bc of how the conjugating capacity of the brain is

Question 4

What is pethidine used for?

Answer 4

• More suitable for use in obstetrics

* Due to shorter duration of action

Question 5

What are the 3 main activities of NSAIDS?

Answer 5

• Analgesic
• Anti-inflammatory
• Antipyretic
By inhibiting COX-2 enzyme which is induced in inflammatoy cells and produces inflammatory prostanoids

Question 6

What does PGE2 do?

Answer 6

• Vasodilator
• Enhance vascular permeability
• Sensitise sensory nerve endings
• Raise body temperature

Question 7

What does PGF2 do?

Answer 7

Sensitises sensory nerve endings

Question 8

What does PGI2 do?

Answer 8

Vasodilate

Enhance vascular permeability

Question 9

What are side effects of NSAIDS?

Answer 9

• Gastric bleeding and ulceration due to inhibition of PGS in gastric mucosa where they are involved in regulation of acid secretion and production of mucus
• Skin reaction -rashes
• Renal insufficiency- PGS involved in regulating renal blood flow

Question 10

What is paracetamol?

Answer 10

• OTC analgesic
• Safe alternative to NSAIDS- gentle on stomach
• Not anti-inflammatory

Question 11

What are side effects of paracetamol?

Answer 11

• Irreversible liver damage in overdose due to production of toxic metabolite which damages cell proteins
• Can be treated by glutathione

Question 12

What are adjuvant drugs?

Answer 12

• Anti-depressants that can produce analgesia in non-depressed patients by inhibiting monoamine reuptake at central synapses e.g amitryptiline
• Local anaesthetics e.g lidocaine prevent AP propagation by blocking voltage gated sodium channels
• Anti-convulsants e.g carbamazepine
• Gabapentinoids