Flashcards in Analgesic Adjunctive Agents (Coanalgesics) Deck (13)
What are analgesic adjunctive agents?
Pharmacological agents which are useful in the management of pain but are not classified as analgesics
--can be used as monotherapy or in combination with non-opioids and opioids
The analgesic adjunctive agents include antidepressants, anticonvulsants, glucocorticoids and other drugs. Antidepresseants and anticonvulsants are the mainstay of treatment for a variety of neuropathic pain. First lets discuss the antidepressants, what are some features?
Serotonin and NE mediate descending inhibition of ascending pain pathways in the brain and spinal cord
--TCAs and SNRIs are used because they enhance both serotonin and NE transmission
SSRIs that enhance only serotonergic transmission are less effective analgesics
Lets discuss a little on the TCAs (tricyclic antidepressants), first off what are they?
(Again these are all SNRIs)
What types of pain can TCAs relieve?
Neuropathic pain including:
--diabetic, postherpetic, polyneuropathy, or nerve injury or fibromyalgia
What are the adverse effects of TCAs?
Constipation, Dry mouth, blurred vision, cognitive changes, tachycardia, urinary hesistation
---all associated with anticholinergic activity
Desipramine and Nortriptyline have fewer anticholinergic and sedative effects (so give to old ppl)
What are the warnings, precautions, and contraindications?
1. Angle-closure glaucoma
3. Urinary retention
5. CVS (2nd or 3rd degree heart block, arrhythmias)
6. Impaired liver function
In addition to TCAs what are other SNRIs?
Venlafaxine and Duloxetine
--lack potent antihistamine, alpha adrenergic blocking, and anticholinergic effects
--used for several types of neuropathic pain
--better tolerated then TCAs
What are adverse effects of Venlafaxine and Duloxetine (SNRIs)?
Moving on to the Anticonvulsants, what are they?
---useful in management of neuropathic pain
First up in the anticonvulsants is Gabapentin and Pregabalin, what are some features?
Gabapentin: postherpetic neuralgia
Pregabalin: neuropathic pain associated with postherpetic neuraligia, diabetic neuropathy and fibromyalgia
---block voltage gated calcium channels (this reduces release of glutamate, NE and substance P)
--Dizziness, Somnolence and Peripheral Edema
Finally Carbamazepine is the third anticonvulsant, what are some features?
Drug of choice for trigeminal neuralgia
--Blockage of voltage gated sodium channels (located in sensory neurons)
--drowsiness, dizziness, nausea, vomiting
--leukopenia but is benign
--aplastic anemia is rare
Next drugs up that can be used as analgesic adjunctive agents are the glucocorticoids. What are some features?
Used in advanced illness
---acute nerve compression, ICP, bone pain, visceral pain, anorexia, nausea and depressed mood
Dexamethasone is the drug of choice: minimal mineralocorticoid effect
(prednisone and methylprednisolone can also be used)