Gabapentin is Used to Treat Nerve Pain

Nerve pain can be a symptom of many different conditions, including cancer, HIV, diabetes, and shingles.

For some, nerve pain is frustrating; for others, nerve pain is devastating and life-changing.

Whether it feels like burning, pinpricks, or sudden shocks of electricity, nerve pain can disrupt your life at home and at work. It can limit your ability to get around. Over time, it can grind you down. Studies show that people with nerve pain have higher rates of sleep problems,anxiety, and depression.Your nervous system is involved in everything your body does, from regulating your breathing to controlling your muscles and sensing heat and cold.

There are three types of nerves in the body:

1. 1. Autonomic nerves. These nerves control the involuntary or partially voluntary activities of your body, including heart rate, blood pressure, digestion, and temperature regulation.
   2. Motor nerves. These nerves control your movements and actions by passing information from your brain and spinal cord to your muscles.
   3. Sensory nerves. These nerves relay information from your skin and muscles back to your spinal cord and brain. The information is then processed to let you feel pain and other sensations.

Because nerves are essential to all you do, nerve pain and damage can seriously affect your quality of life.

When you have a serious medical condition such as cancer or HIV, dealing with the additional misery of nerve pain can be especially hard. But there is good news. While nerve pain can’t always be cured, it can be treated — and there are a lot of good options available.

Experts believe that 40 million Americans are living with nerve pain. The impact of nerve pain is tremendous. Both the costs to the healthcare system as well as loss of wages and productivity are staggering.

Neuropathic pain is a chronic debilitating pain syndrome that is complex to treat. Current medication management for neuropathic pain includes select neuromodulating agents such as anticonvulsants, serotonin norepinephrine reuptake inhibitors, tricyclic antidepressants, and certain opioids. Gabapentin remains among the most commonly used anticonvulsants for neuropathic pain.

The established therapeutic dosing for gabapentin in neuropathic pain trials is 1800-3600 mg/day in 3 divided doses in patients with normal renal function.3 This means the minimum effective dose is 600 mg 3 times a day. Renal adjustments are recommended in patients with CrCl below 60 mL/min. For patients on dialysis, gabapentin can often be 3 times weekly following dialysis.

Several cross-sectional studies have reported gabapentin being used in subtherapeutic doses among most patients. In a retrospective analysis of 939 patients with post-herpetic neuralgia, the mean daily dose of gabapentin was 826 mg. In another 2-year retrospective study of 151 veterans with various neuropathic pain syndromes, the median daily dose for gabapentin was 900 mg. In both studies, the most prevalent gabapentin dosing was half the therapeutic dosing.

The cornerstones of effective pharmacotherapy are the right patient, the right drug, and the right dose. If an analgesic medication is being used at a suboptimal dose, oftentimes a knee-jerk reaction is to add another analgesic for synergy.

While this may well be indicated under appropriate circumstances, it is inappropriate without maximizing the dose of each single agent with careful attention to dose titration in order to minimize toxicity of each add-on.

Consider for example a patient who starts low dose gabapentin that was not properly titrated, returns for follow-up and is given an additional prescription for duloxetine for neuropathic pain since gabapentin “does not work,” assuming there are no tolerability issues.

This adds to polypharmacy, increased costs, and the pain remains inadequately treated.

Pharmacists as medication experts can collaborate with prescribers to optimize the rational use of gabapentin in neuropathic pain. First, let’s take a look into the pharmacology of gabapentin.

Gabapentin is a gaba aminobutyric acid (GABA) analogue anticonvulsant but does not exhibit any significant agonistic effects at the GABA receptor.  Gabapentin inhibits the alpha-2-delta subunit of the N-type voltage-gated calcium channels. Receptor binding causes presynaptic inhibition of excitatory neurotransmitter release (i.e. glutamate) thereby attenuating neuropathic pain.

Gabapentin’s counterpart, pregabalin, shares the same mechanism of action but there are key pharmacologic differences between both medications. Gabapentin has saturable, non-linear absorption kinetics, where bioavailability decreases as the dose increases.

Following oral administration, gabapentin’s bioavailability is 60%, 47%, 34%, and 33%, following 900, 1200, 2400, and 3600 mg/day in 3 divided doses, respectively. On the other hand, pregabalin has ≥90% bioavailability irrespective of the dose, leading to more predictable kinetics. Pregabalin boasts a binding affinity for the alpha-2-delta receptor that is six times greater than that of gabapentin.

How Are Nerve Pain and Nerve Damage Treated?

In many instances, nerve damage cannot be cured entirely. But there are various treatments that can reduce your symptoms. Because nerve damage is often progressive, it is important to consult with a doctor when you first notice symptoms. That way you can reduce the likelihood of permanent damage.

Often, the first goal of treatment is to address the underlying condition that’s causing your nerve pain or nerve damage. This may mean:

• • Regulating blood sugar levels for people with diabetes
  • Correcting nutritional deficiencies
  • Changing medications when drugs are causing nerve damage
  • Physical therapy or surgery to address compression or trauma to nerves
  • Medications to treat autoimmune conditions

Additionally, your doctor may prescribe medications aimed at minimizing the nerve pain you are feeling. These may include:

• • Pain relievers
  • Tricyclic antidepressants
  • Certain anti-seizure drugs – Gabapentin

Complementary and alternative approaches may also help alleviate your nerve pain and discomfort. These include:

• • Acupuncture
  • Biofeedback
  • Hypnosis
  • Meditation