Lidocaine injected into the epidural space around the lumbar spinal cord acts as an anesthetic that mitigates the pain of childbirth (this is called an epidural). Lidocaine works by preventing depolarization of the action potential in the sensory neuron. Lidocaine blocks the the sodium channel activation gate on the cytoplasmic side of the membrane.

Lidocaine is a weak base and at physiological pH exists in 2 forms: neutral and positive, where the positive form is dominant.  As the pH decreases the concentration shifts in favor of the positive state even more. Justify why

  1. only the neutral form is the active form of the drug and
  2. why a drop in pH decreases the drug’s effectiveness.

Physiology In Action Guidelines: One (1) page, double-spaced, written assignment (introduction, body, conclusion format)

    1. State the position in the introduction.
    2. Examine, scrutinize, and decide what information given is relevant to your position.
    3. Provide additional information in support as needed.
    4. Explain your conclusions based in the evidence.