analgesics 1: introduction

Question 1

Analgesics timeline

waht does the term “opiates” refer to

Answer 1

natural opioids like heroin, morphine and codeine

Question 2

Analgesics timeline

what does the term “Opioids” refer to

Answer 2

refers to all types of opioids like natural, semisynthetic and synthetic

Question 3

The WHO analgesic Ladder

Outline the WHO analgesic ladder

Answer 3

Step 1: Non-opioid plus optional adjuvant analgesics for mild pain

Step 2: if pain is still persistent, administer weak opioid plus non-opioid and adjuvant analgesics for mild to moderate pain

Step 3: if pain is still persistent after step 2, administer strong opioid plus non-opioid and adjuvant analgesics for moderate to severe pain

if any drugs are toxic to the patient, you should move down a step

Question 4

Pain overview - where do analgesics work and outline the process

Answer 4

1. nerve endings respond to stimulation by: acid (H+), temperature, 5-HT (serotonin) etc released from damaged cells, bradykinin (BK) released from blood vessels and substance P (sP) is released from nociceptors.
2. this information travels to the spinal cord, where glutamate (Glu) and substance P (sP) released from primary afferent terminals activate glutamate and neurokinin-1 (NK-1) receptors respectively on spinal neurons
3. Activation of descending noradrenergic and/or 5HT systems leads to activation of spinal inhibitory interneurons
4. spinal inhibitory interneurons release enkephalins (Enk, endogenous opioids) or GABA as neurotransmitters

Question 5

nerve endings

what do opioids, cannabinoids and noradrenaline work to open in nerve endings and what does this do?

Answer 5

they work to open potassium channels, which hyperpolarises the nerve membrane, stopping depolarisation of the nerve membrane which stops the pain signal going up the spinal cord to the brain