Pharmacology Of Pain Flashcards
Types of pain
Nociceptive
Acute
Chronic
Neuropathic
Neuropathic pain
Chronic maladaptive pain after traumatic brain injury or spinal cord injury
How long does chronic pain last
12wk+
Which type of pain generally responds to analgesics and which doesn’t
Nociceptive responds
Neuropathic doesn’t
Targets for pain medications
COX2
NOS
NMDA and nonNMDA glutamate receptors
NK1 receptors
Opioid receptors
Factors influencing pain perception
Cognition - attention, distraction, control
Mood
Context - expectations, beliefs, placebo
Genetics
Chemical and structural - nerve dysfunction
Injury - sensitisation
Opioid peptides involved in nociception
Leu enkephalin
Met enkephalin
Dynorphin A
Nociceptin
What type of peptide is substance P
Tachykinin
3 families of opioid receptors
Mu - μ1 μ2 μ3
Delta - δ1 δ2
Kappa k1 k2 k3
Effects of opioids
Analgesia
Pupillary constriction
Sedation
Euphoria
Dysphoria
Respiratory depression
Reduced GI motility
Dependence
Drowsiness/legarthy
Nausea+vomiting
Hypotension
Itching
Why do opioid agonists have a broad spectrum of effects
Widespread distribution of opioid receptors
Mechanism of morphine
Activate potassium conductance and decrease calcium conductance causing decreased excitability and NT release
Opioid drugs
Codeine
Fentanyl
Hydrocodone
Hydromorphone
Levorphanol
Methadone
Oxycodone
Oxymorphone
Propoxyphene
Tramadol
What drug is used to reverse opioid overdose
Naloxone
Naloxone
Opiate antagonist used to reverse overdose
Why should opiates not be underdosed
Risk of tolerance developing
3 steps of the analgesic ladder
1 Non opioids + adjuvants
2 moderate efficacy opioids + non opioids + adjuvants
3 high efficacy opioids + non opioids - adjuvants
Non opioid painkillers
Paracetamol - analgesic antipyretic
Aspirin - analgesic antipyretic anti inflammatory
Ibuprofen, diclofenac, ketoprofen - analgesic, anti inflammatory
Selective COX2 inhibitors
Anticonvulsants - neuropathic pain, trigeminal neuralgia
Tricyclic antidepressants - neuropathic pain, cancer pain
SSRI
TRPV1 receptor ligands
NMDA glutamate receptor agonists
GABA receptor agonists
Local anaesthesia
Which drugs acts on COX 1 and 2
Paracetamol
Aspirin
Ibuprofen
Diclofenac
Ketoprofen
Selective COX 2 inhibitors
Anticonvulsant drugs
Carbamazepine
Sodium valproate
Pregabalin
What type of drug is Amitryptyline
Tricyclic antidepressant
What channel do carbamazepine and sodium valproate act on
Sodium
What channel does pregabalin act on
Calcium - alpha2delta subunit
Tricyclic antidepressants mechanism
Inhibit amine reuptake
Block sodium and calcium channels
What type of drug is capsaicin
TRPV1 receptor ligand
What type of drugs are ketamine and dextromethorphan
NMDA glutamate receptor agonist
What type of drug is baclophen
GABA receptor agonist
1st line drugs for neuropathic pain
SSRI
Tricyclic antidepressants
Anticonvulsants
Local anaesthetic drugs
Lignocaine
Bupivacaine
Prilocaine
Local anaesthetic mechanism
Block sodium channels
Effects of anaesthetic system toxicity
Hypotension
Respiratory depression
Bradycardia
General anaesthetic mechanism
Activate inhibitory receptors or inhibit excitatory receptors
Do general anaesthetics act as analgesics
No, except ketamine
What type of drugs are halothane enflurane isoflurane and nitrous oxide
Inhalation all general anaesthetics
What type of drugs are propofol thiopental etomidate ketamine and midazolam
IV General anaesthetics
Trigeminal neuralgia
Sudden paroxysmal attacks of electric shock like/sharp/stabbing pain to the face lasting a few seconds to a few minutes
Trigeminal neuralgia main cause
Compression distortion or stretching of Trigeminal nerve by a branch of AICA or PICA
Trigeminal neuralgia treatment
Carbamazepine, baclofen, phenytoin, sodium valproate, clonazepam
Benzodiazepine mechanism
Active GABAa receptors
