ABEM Pharmacology & Medical Management Flashcards

Excessive use of isoniazid (INH) for tuberculosis can cause peripheral neuropathy due to depletion of which vitamin?

Answer: Vitamin B6 (pyridoxine)

INH competitively inhibits pyridoxine phosphokinase, depleting active vitamin B6 and causing an axonal sensorimotor neuropathy.

A patient on amiodarone develops a demyelinating neuropathy. Which finding would you expect on nerve conduction studies?

Answer: Slowed conduction velocity with prolonged distal latencies

Amiodarone-induced neuropathy is demyelinating, so NCS shows slowed conduction velocities and prolonged distal latencies rather than reduced amplitudes.

Which immunosuppressant is commonly used as a steroid-sparing agent in chronic inflammatory demyelinating polyneuropathy (CIDP)?

Answer: All of the above may be used

Azathioprine, mycophenolate mofetil, and cyclosporine are all used as steroid-sparing agents in CIDP, with none clearly superior in randomized trials.

Botulinum toxin injected for spasticity reduces muscle tone by:

Answer: Cleaving SNARE proteins, preventing ACh vesicle release

Botulinum toxin cleaves SNARE proteins (such as SNAP-25 or synaptobrevin) required for synaptic vesicle fusion, blocking presynaptic acetylcholine release.

A diabetic patient presenting with a painful, asymmetric motor neuropathy affecting the thigh is most likely experiencing:

Answer: Diabetic amyotrophy (lumbosacral radiculoplexus neuropathy)

Diabetic amyotrophy (also called lumbosacral radiculoplexus neuropathy) presents with acute painful, asymmetric proximal lower limb weakness and is immune-mediated.

Which medication can cause myopathy characterized by elevated CK, myalgia, and proximal weakness in susceptible individuals?

Answer: Statins (HMG-CoA reductase inhibitors)

Statins can cause a spectrum of muscle injury from mild myalgia to rhabdomyolysis, and in rare cases an immune-mediated necrotizing myopathy with anti-HMGCR antibodies.