Analgesics Flashcards
Define acute/nociceptive pain.
Short-term pain, with an easily identifiable cause.
Define chronic/neuropathic pain.
Pain which persists. Constant and intermittent.
Define allodynia.
Pain from a stimulus that does not usually cause pain.
Define parasthesis.
Painful feelings e.g pins and needles. With no apparent stimulus.
What are 3 classes of drugs used for analgesia?
Opioids. Antidepressants/Antiepileptics. Local Anaesthetics.
What is the mechanism of action for opioids?
Act at the level of the spinal cord and the CNS. Decrease neurotransmitter release and block postsynaptic receptors. Activate inhibitory pathways.
What are the advantages of using opioids?
Highly effective, range of durations of effects, variety of routes.
What are the side effects of opioids?
N&V, constipation, drowsiness, respiratory depression, hypotension, sedation, dependance.
What can opioids interact with?
Alcohol, MAOIs, SSRIs
What are opioid μ-receptors?
Involves CNS, spinal cord, Peripheral sensory neurons and GI tract. Responsible for most of the analgesic effects. Most opioids are μ-receptor agonists.
Examples of opioids?
Morphine, methadone, codein, tramadol, fentanyl
What are the 2 types of antidepressants that can be used for analgesia?
Serotonin and noradrenaline reuptake inhibitors (SNRI).
Selective Serotonin Reuptake Inhibitors (SSRI).
What are SNRIs used for?
Highly effective for neuropathic pain.
What are examples of SNRI drugs?
Venlafaxine - prescribed for diabetic neuropathy, Duloextine - prescribed for peripheral neuropathy.
What are example of SSRI drugs?
Paroxetine, Citalopram.
How do SNRI/SSRI work?
Prevent the recycling of neurotransmitters and enhance the signal.
What are the side effects of SNRIs?
Nausea, insomnia, sedation, headache, dizziness. Can cause: epilepsy, cardiac disease, diabetes.
How do antiepileptic drugs work for analgesia?
Inhibit voltage gated sodium channels. Inhibit voltage gated calcium channels. Inhibit Glutamate and GABA receptors. This inhibits action potentials firing and limits neuronal excitation.
What is carbamazepine?
Antiepileptic drug. Used to treat different types of neuralgia and diabetic neuropathies.
What are the side effects of carbamazepine?
Dizziness, drowsiness, fatigue, nausea, hepatoxicity, renal impairment, skin reactions, anorexia, tremor.
What is Gabapentin?
An anti epileptic drug. Used to treat neuropathy of the face, neuralgia, sciatic type pain, neuropathy.
What are the side effects of gabapentin?
Anorexia, dyspepsia, tremor.
How do local anaesthetics work?
Inhibit voltage gated sodium channels or NMDA receptors. Prevent nerve-cell communication. Inhibit firing and prevent impulse transmission.
What is the name of the local anaesthetic that blocks sodium channels?
Lidocaine. IV.
What are the side effects of lidocaine?
CNS effects, respiratory depression, convulsions, hypotension, bradycardia.
What does Ketamine do?
Blocker of Glutamate receptors (NMDA).
What are the side effects of ketamine?
HTN, tachycardia, tremor, myocardial depression.
