Pain/NSAIDs/Opiods/steroids

Question 1

What are the two main functions/mode of action of NSAIDs?

Answer 1

• Inhibit inflammation, pain and fever
• inhibit prostaglandin synthesis by blocking two enzymes known as Cyclooxyrgenase (COX 1 and COX 2)

(There is COX 3 but little is know about it)

Question 2

Prostaglandins produced by COX 1 promote….

Answer 2

• Inflammation, pain and fever
• Gastric mucosa (stop the stomach from digesting itself)
• Renal perfusion
• Production of platelets

(NSAIDs inhibiting COX 1 - risk of GI bleeds or ulcers, risk of renal problems and problems with platelet production)

Question 3

Prostaglandins produced by COX 2 effect …..

Answer 3

• Inflammation, pain and fever
• inhibit platelet production

(Drugs that inhibit COX 2 - risk for patients with cardiac disease or cancer as they will have an increased likelihood of clots)

Question 4

Drugs that interact with NSAIDs are?

(5)

Answer 4

• Diuretics and antihypertensives - reduced effect (sodium retention and reduction of renal function)
• Oral anticoagulants- increased effect (Increased risk of GI bleed secondary to the protein binding of NSAIDs so more free drug)
• Lithium - increased effect (reduced renal clearance can lead to lithium toxicity)
• Anticonvulsants - increased effect (displaced protein binding)
• Digoxin - increased effect (reduced renal clearance can lead to toxicity)

Question 5

1) What is an opioid?

2) What is an opiate?

Answer 5

1) An opioid is a natural or synthetic compound that binds to opioid receptors in the body

2) An opiate is a chemical compound extracted from the poppy plant

Question 6

What are the 3 main opioid receptors?

Answer 6

1) Mu receptor:
* responsible for most analgesic effects
* common side effects
* supraspinal/spinal effects - effects central processing of pain, perception of pain and stops signals travelling from the spine to the brain

2) Delta:
* more important in periphery and may contribute to analgesia

3) Kappa:
* Contributes to analgesia at spinal level * involved in sedation and dysphoria
* Doesn’t contribute to dependence

Question 7

What are the most common side effects of opioids?

(7)

Answer 7

• Respiratory depression
• Depression of cough reflex
• Dependance - rare if used appropriately
• Reduced GI motility - constipation
• Sedation
• Tolerance (increased dose to get same therapeutic effect)
• nausea and vomiting (usually settles within 48 hours)

Question 8

What are the pharmacokinetics of opioids?

(6)

Answer 8

• Absorption of oral morphine is erratic and variable
• Considerable 1st pass metabolism
• Half life 3-6 hours
• Conjugated in liver - glucuronide is the metabolite of morphine
• Excreted in urine
• Some biliary excretion snd enterohepatic uptake

Question 9

What are cytokines?

Answer 9

Cytokines are signalling proteins that help control inflammation in the body. Too many cytokines can lead to excess in inflammation and conditions like autoimmune diseases

Question 10

What is neuropathic pain?

(2)

Answer 10

• Neuropathic pain is characterised by neuronal hyoerexcitability in damaged areas of the nervous system
• The neuronal hyperexcitability and molecular changes have many features common with certain forms of epilepsy. This has led to the use of anticonvulsant drugs for the treatment of neuropathic pain

Question 11

How do steroids work?

Answer 11

Steroids switch off inflammatory response by formation of most mediators (switch genes on and off)

(Steroids represent some of the most powerful anti inflammatory drugs known)

Question 12

What are the main side effects of steroids?

(11)

Answer 12

• Euphoria
• Psychotic symptoms
• Buffalo hump
• Hypertension
• Thinning of skin
• Muscle wastage (thin arms and legs)
• Moon face
• Increased abdominal fat
• Easy bruising
• Poor would healing
• Steroid induced diabetes

(Because of the anti inflammatory effect, steroids also effect the body’s natural ability to fight infection)