2.1 analgesics

Question 1

Please explain the different pharmacological approaches to achieve analgesia in pain patients.

Answer 1

Target brain insular cortex (general anesthetics, psychatric medication, opioids), spinal cord (opioids), nerves (local anaesthetics) or nociceptors (opioids, non-opioids, topical anaesthetics) to achieve analgesia.

Question 2

Please discuss the clinical implications of the WHO‘s analgesic ladder

Answer 2

Step 1: mild pain -> non-opioids (paracetamol, ibuprofen)

step 2: mild/moderate pain –> weak opioid (codeine, tilidine) + non-opioids (synergistic effects) + co-analgesic(antidepressant, anticonvulsant) + adjuvant (control of major ADR)

step 3: moderate/severe pain: strongs opioids (morphine, oxocodone, fentanyl, methadone) + non-opioids + co-analgesic + adjuvant

–> no ceiling effect in opioids

Question 3

Please give examples for non-opioids, weak opioids, strong opioids, co-analgesics and adjuvants in pain therapy.

Answer 3

• non-opioids (paracetamol, ibuprofen, diclofenac, ASS, metamizole, flupiritine, Coxibs)
• weak opioid (codeine, tilidine)
• strongs opioids (morphine, oxocodone, fentanyl, methadone)
• co-analgesic (antidepressant, anticonvulsant)
• adjuvant (control of major ADR like nausea, vomiting (antiemetics), constipation (laxatives)

Question 4

What are the details of the MOAs of NSAIDs?

Answer 4

NSAIDs inhibit the contitutive COX-1 (predominatly) and/or the inducible COX-2 –>

These Cyclooxygenases normally catalyse the formation of arachidonic acid to prostaglandins. These sensitize nociceptors to pain mediators (substace P…)

Question 5

What are the details of the MOAs of opioids?

Answer 5

Agonism at µ-opioid receptors (MOR) which are inhibitory GPCR
Binding -> activation of Gaplha1 subunit -> activity of adenylcyclase decreased -> decreased cAMP concentration
-> activation of hyperpolarising K+ channels -> prevention of generation of action potential

Question 6

How do NSAIDs exert their gastrointestinal ADRs?

Answer 6

Topic acidic effect as gastric & duodenal ulcers and GI bleedings
decreased NO production -> mucosal ischemia,
inhibition of PG-E2 synthesis -> decreased HCO3- and mucus production

Question 7

What are the major contraindications of ASA ? Why exactly are those conditions contraindications?

Answer 7

Active GI ulcers,
pregnancy (prenatal closure of fetal ductus arteriosa),
children < 16 years (-> Reye´s syndrom when having viral infection + ASA = fumlinant hepatitis!),
asthma (leukotriens),
gout (inhibition of renal urate excretion)

Question 8

What are the major contraindications of ibuprofen? Why exactly are those conditions contraindications?

Answer 8

DUe to unslective COX inhibition:
high Active GI ulcers risk (=ADR & CI),
not during pregnancy (prenatal closure of fetal ductus arteriosa),
not for asthmatics (accumulation of HPETE-leukotriens and EET),
not for IBD (may be boosted by ibuprofen)
high stroke risk

Question 9

What are the differences between opiates and opioids? Please give examples.

Answer 9

Opiates: natural alkoloids extracted from raw opium (morphine, codeine)
Opioids: (semi)synthetic derivates (hydromorphone, oxocodone, fentanyl, heroin?)

Question 10

Please discuss the CNS effects of opioids.

Answer 10

CNS: analgesia (inhibition of neurons/MOR agonism),
respiratory suppression (MOR agonism in respiratory centre -> can be fatal), cough suppression (MOR agonism in cough centre), 
emetic/antiemetic (differentiates from the point of time: emetic -> antiemetic), hypothermia (agonism at hypothalamus), 
miosis (excessive constriction of pupils), Hypotension (agonism at baroreceptors), 
bradykardia (activation of n. vagus), sedation (liberation of dopamine in limbis system), 
euphoria (liberation of dopamine in nucleus accumbens -> at Cmax peaks)

Question 11

Why can opioids be used for indications like diarrhoea and cough?

Answer 11

Due to their major ADR at peripheral µ-opioid receptors in the smooth miscle cells: delayed gastric emptying, spastic constipation, urinary retention
And their agonism at µ-opioid receptors in the cough centre (CNS)

Question 12

Please discuss the peripheral effects of opioids.

Answer 12

peripheral: analgesia (reduces sensitivity of nociceptors to pain mediators), delayed gastric emptying, spastic constipation (agonism at smooth muscle cells), urinary retention (contraction of sphincter vesicae)