Gout and Neuropathic Pain

Question 1

Gout Patho

Answer 1

• after metabolism of purine, sodium urate crystals are deposited in the joint which leads to inflammation
• inflammation and mechanical grinding on these crystals leads to pain in joint

Question 2

Colchicine

Answer 2

• MOA: inhibits migration of granulocytes to inflamed area and reduces lactic acid and proinflammatory enzyme release
• ONLY works with gout
• SE: inhibits growth, histamine release, insulin release. Most common are NVD and abd pain.

Question 3

Allopurinol

Answer 3

• MOA: inhibits uric acid synthesis by inhibiting xanthine oxidase
• SE: itching and eruptions of erythematosus
• renal patients need lower doses

Question 4

Febuxostat

Answer 4

• MOA: inhibits xanthine oxidase to stop uric acid synthesis
• SE: nausea, rash, joint pain, gout flare, and lever problems
• similar to allopurinol but requres no dose adjustment for renal pt

Question 5

Uricosuric drugs

Answer 5

-these drugs increase excretion of uric acid

Probenecid and Sulfinpyrazone

Question 6

Probenecid

Answer 6

• inhibits inorganic acid transport

- SE:GI irritation and skin rash

Question 7

Sulfinpyrazone

Answer 7

• inhibits tubular reabsoption of uric acid

- SE:GI irritation and several drug interactions

Question 8

what is neuropathic pain?

Answer 8

• chronic pain caused by damage, injury, or dysfunction to neurons or their myelin sheaths. This causes sensory neurons to fire inappropriately.
• There are lots of causes to neuropathic pain
• To differentiate neuropathic pain from inflammatory pain ask about burning, shooting, stabbing, shocking, tingling, or numb pain

Question 9

Hyperalgesia vs Aldynia

Likely test question

Answer 9

• Hyperalgesia is an exaggerated response to a stimulus that normally evokes pain
• Allodynia is when a stimulus that normally wouldn’t cause pain evokes a painful response

Question 10

patho of neuropathic pain

Answer 10

-upregulation of sodium channel is responsible for increased transmission of neuronal signal.

Question 11

indications for the use of antidepressants in neuropathy

Answer 11

migraine and tension headaches, pain after shingles or stroke, diabetic neuropahty, and fibromyalgia

Question 12

antidepressants used for neuropathic pain

Answer 12

AMITRIPTYLINE, desipramine, nortriptyline, imipramine, tramadol, and doxepin

Question 13

MOA of antidepressants for neuropathic pain

Answer 13

potentiates descending inhibitory transmission by blocking reuotake of NE and seratonin
-also vasodilatory and local anesthetic effects

Question 14

Dosage of antidepressants for neuropathic pain

Likely a test question

Answer 14

• the dosage needed for neuropathy is much lower than that required for depression
• whereas depression requires several weeks of therapy to work, antidepressants work nearly immediately for neuropathy
• titrate the dose of antidepressant to therapeutic endpoint and SE profile

Question 15

SE of antidepressants for neuropathic pain

Answer 15

anticholinergic and proarrhythmic

Question 16

Indications for the use of anticonvulsants for neuropathic pain

Answer 16

• trigeminal neuralgia, diabetic neuropathy, pain after shingles, any other neuropathic pain
• not for gullaine-barre

Question 17

anticonvulsants approved for neuropathic pain

Answer 17

carbamazepine, phenytoin, valproic acid, clonazepam, GABAPENTIN, PREGABALIN, lamotrigine, and zonisamide

• carbamazepine was popular
• phenytoin works, but not ideal r/t gingival hyperplasia

Question 18

Dosage of anticonvulsants for neuroppathic pain

Answer 18

• Unlike antidepressants, the neuropathic dose for anticonvulsants is similar to the dose for epilepsy
• these can be used alone or in combination with analgesics
• remember phenytoin requires blood monitoring
• titrate to therapeutic endpoint

Question 19

Adverse effects of anticonvulsants for neuropathic pain

Answer 19

• each anticonvulsant has its own SE profile, but the main one is drowsiness
• the exception is gabapentin and pregabalin which have very few SE

Question 20

Antihistamines for neuropathic pain

Answer 20

• hydroxyzine, orphenadrine, and diphenhydramine have some analgesic effect for neuropathy, but the effect is poorly understood
• can potentiate effects of analgesics
• limited use

Question 21

Cannabinoids for neuropathic pain

Answer 21

-indicated for MS and other demyelinating neuropathies