Gabapentin For Pain

What is gabapentin?

Gabapentin is a prescription drug. It comes as an oral capsule, an immediate-release oral tablet, an extended-release oral tablet, and an oral solution.

Gabapentin oral capsule is available as the brand-name drug Neurontin. It’s also available as a generic drug. Generic drugs usually cost less than the brand-name version. In some cases, the brand-name drug and the generic version may be available in different forms and strengths.

Why it’s used?

Gabapentin oral capsule is used to treat the following conditions:

Seizures: Gabapentin is used to treat partial (focal) seizures. It’s taken together with other seizure medications in adults and in children 3 years of age and older who have epilepsy.
Postherpetic neuralgia: This is pain from nerve damage caused by shingles, a painful rash that affects adults. Shingles appears after infection with the varicella zoster virus. This virus occurs in people who have had chicken pox.

Gabapentin may be used as part of a combination therapy. This means you may need to take it with other drugs.

How it works?

Gabapentin belongs to a class of drugs called anticonvulsants. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

It’s not fully understood how gabapentin works. For postherpetic neuralgia, it seems to prevent the increase in sensitivity to pain that occurs. For seizures, it may alter the effect of calcium (low levels of calcium may cause seizures).

Gabapentin is off label used for treatment of nerve pain not all kinds of pains. 65% patients think it is effective for pain but as high as 35% think it doesnot work.

bubba smith Reviewed it very good for nerve pain:

“I have severe spine damage. t7 t8 and disc in between basically gone, nerve pain unbelievable. I tried lyrica in large dose and no relief.

Then one doctor said some meds don’t work on some but do on others you just have to get the correct one. So I tried gabapentin and to me it was a life saver, within 3 days the pain was gone or close to gone. 1800 mgs a day ( 6x300mg) plus 40 mg of oxyneo (4x10mg) which is oxycodone time release formula.

The pain specialist say maybe more dose needed but I can’t function properly. That is my minimum dose even drop 1 pill out of them amounts I can feel the difference in pain.

The side effects to me are , tiredness, constipation, memory, blurred vision, moody, seems heat and humid days if outside I get really disoriented so I stay inside”

But a Anonymous guy reviewed it not good for Knee Pain:

“My Husband was given this medication due to suffering long term knee pain. He took it for approx 6 weeks max and had to stop.

The most awful side effects you can imagine for the whole time blighted him. Maybe he was just unlucky and this med didn’t suit him but it’s Cons certainly outweighed its Pros in his case.

Weight gain Excess gas Dizzyness Nausea Vomiting Diarrhoea Headaches…… Not a good one for him at all. UK Based.”

Because I am a recovering alcoholic it is crucial for me to find non-narcotic treatment for the persevering pain of my chronic pancreatitis.

I was feeling a bit hopeless with the repeated prescriptions of pain meds (which of course offer only temporary relief, and for me a danger of over-use), until my GI prescribed me Gabapentin.

This med has been incredibly successful in mitigating my pain, while also giving me huge energy (I’m a consistent runner so this factor is welcomed), and allowing me to move forward with my sobriety.

I give it four stars, though I realize like anything, it’s not for everyone. That said, good luck to you all with finding what works.

Gabapentin is Widely Used for Pain Relief

Gabapentin is approved to treat the type of nerve pain (neuralgia) that results from nerve damage. Gabapentin is used to treat neuralgia caused by a herpes zoster viral infection, also known as shingles. This pain is called post-herpetic neuralgia (PHN), and it can be severe and chronic. Gabapentin is also used to treat pain from diabetic neuropathy, which happens when nerves in the feet damaged by diabetes cause chronic burning pain.

The exact way that gabapentin works to relieve pain is not known. It may change the way the body senses and reacts to pain. Gabapentin is used to manage long-term (chronic) pain, not to be taken for pain as needed. Chronic pain can interfere with sleep and work, and lead to depression.

Studies show that pain relief may start within one week and reach a maximum effect in about 4 weeks. It can take this long because gabapentin is usually started at a low dose and gradually increased over time until it works.

For treating neuralgia, gabapentin is often started at 300 mg per day and gradually raised by 300 mg per day. One 2017 review of 37 studies found that pain relief usually occurs at a dose of 1,200 mg or more.

The same review compared gabapentin to an inactive medicine (placebo) in almost 6,000 adults with chronic pain from PHN or diabetic neuropathy. Study participants were given either gabapentin or a placebo for 4 to at least 12 weeks. The results showed that 30-40% of people taking gabapentin were able to reduce their pain by half or more, compared to 10-20% of people taking the placebo.

Although some people may get significant relief, others may have side effects without relief of pain. More than half of people taking gabapentin did not get significant relief and had side effects from the drug.

According to the review, about 60% of people taking gabapentin had side effects, including:

Dizziness
Sleepiness
Water retention (edema)
Clumsiness while walking (ataxia)

It does not typically make pain worse: In trials comparing gabapentin side effects to placebo side effects, only 1% of people reported increased pain, and this was the same for gabapentin and placebo.

Once you find the dose that relieves neuralgia for you, it is important not to stop taking it suddenly. Stopping suddenly can lead to withdrawal symptoms such as:

Anxiety
Insomnia
Nausea
Pain
Sweating

Gabapentin Dosage

Usual Adult Dose of Gabapentin for Epilepsy:

Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses. If necessary, the dose may be increased using 300 mg or 400 mg capsules three times a day up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long-term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the three times a day schedule should not exceed 12 hours.

The safety and effectiveness of gabapentin available under the trade name Gralise (R) or Horizant (R) in patients with epilepsy has not been studied.

Usual Adult Dose for Postherpetic Neuralgia:

Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.

The dose may be titrated up as needed for pain relief to a daily dose of 1800 mg.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses.
Efficacy was demonstrated in clinical studies over a range of 1800 mg/day to 3600 mg/day. However, no additional benefit was demonstrated from the use of doses over 1800 mg/day.

Gabapentin available under the trade name Gralise (R):
Maintenance dose: Gralise (R) should be titrated to 1800 mg orally once daily with the evening meal.
Recommended titration schedule:

Day 1: 300 mg orally with the evening meal
Day 2: 600 mg orally with the evening meal
Days 3 through 6: 900 mg orally with the evening meal
Days 7 through 10: 1200 mg orally with the evening meal
Days 11 through 14: 1500 mg orally with the evening meal
Day 15: 1800 mg orally with the evening meal

Gralise (R) is not interchangeable with other gabapentin products because of differing pharmacokinetic profiles that affect the frequency of administration.
Gabapentin enacarbil extended release tablets available under the trade name Horizant (R):
The recommended dosage is 600 mg orally twice daily. Therapy should be initiated at a dose of 600 mg orally in the morning for 3 days of therapy, then increased to 600 mg twice daily (1,200 mg/day) on day four.

Gabapentin enacarbil extended release tablets available under the trade name Horizant (R) and gabapentin are not interchangeable.

Usual Adult Dose for Restless Legs Syndrome:

Gabapentin enacarbil available under the trade name Horizant (R):
600 mg orally once daily with food at about 5 PM

Usual Pediatric Dose for Epilepsy:

Less than 3 years: Effectiveness has not been established.

Greater than or equal to 3 and less than 12 years:
Starting Dose: ranges from 10 to 15 mg/kg/day in 3 divided doses.
Effective Dose: reached by upward titration over a period of approximately 3 days. The effective dose of gabapentin in patients 5 years of age and older is 25 to 35 mg/kg/day and given in divided doses (three times a day). The effective dose in pediatric patients ages 3 and 4 years is 40 mg/kg/day and given in divided doses (three times a day). Gabapentin may be administered as the oral solution, capsule, or tablet, or using combinations of these formulations. Dosages up to 50 mg/kg/day have been well tolerated in a long term clinical study. The maximum time interval between doses should not exceed 12 hours.
Greater than 2 years:
Initial dose: 300 mg orally on day one, 300 mg orally twice a day on day two, then 300 mg orally 3 times a day on day three.
Maintenance dose: 900 to 1800 mg orally in 3 divided doses. If necessary, the dose may be increased using 300 mg or 400 mg capsules three times a day up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the three times a day schedule should not exceed 12 hours.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

For oral dosage forms (capsules, liquid, and tablets):
- For epilepsy:
  - Adults and teenagers 12 years of age and older—At first, 300 milligrams (mg) 3 times per day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 1800 mg per day.
  - Children 3 to 12 years of age—Dose is based on body weight and must be determined by your doctor. The starting dose is 10 to 15 milligrams (mg) per kilogram (kg) of body weight per day and divided in 3 doses. Your doctor may adjust your dose as needed.
  - Children younger than 3 years of age—Use and dose must be determined by your doctor.
- For postherpetic neuralgia:
  - Adults— At first, 300 milligrams (mg) as a single dose in the evening. Your doctor may adjust your dose as needed. However, the dose is usually not more than 1800 mg per day.
  - Children—Use and dose must be determined by your doctor.
For oral dosage form (extended-release tablets):
- For postherpetic neuralgia:
  - Adults— At first, 600 milligrams (mg) in the morning. Then, your doctor will increase your dose to 600 mg 2 times per day.
  - Children—Use and dose must be determined by your doctor.
- For restless legs syndrome:
  - Adults—600 milligrams (mg) as a single dose at about 5 PM.
  - Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Horizant® extended-release tablets: If you miss a dose of this medicine, skip the missed dose and go back to your regular dosing schedule.

What is Gabapentin Used for ? What is the Off-Label Usages of Gabapentin ?

Gabapentin is used to help control partial seizures (convulsions) in the treatment of epilepsy. This medicine cannot cure epilepsy and will only work to control seizures for as long as you continue to take it.

Gabapentin is also used in adults to manage a condition called postherpetic neuralgia, which is pain that occurs after shingles.

Gabapentin extended-release tablet is used to treat a condition called Restless Legs Syndrome (RLS). RLS is a neurologic disorder that makes the legs feel uncomfortable. This results in an irresistible feeling of wanting to move your legs to make them comfortable.

Gabapentin works in the brain to prevent seizures and relieve pain for certain conditions in the nervous system. It is not used for routine pain caused by minor injuries or arthritis. Gabapentin is an anticonvulsant.

Gabapentin is also used to treat certain types of long-lasting pain caused by damage to nerves. This type of pain, called neuropathic pain, can be caused by a number of different diseases, such as diabetes (where it is called diabetic neuropathy) and shingles (where it is called postherpetic neuralgia).

Although gabapentin is only licensed for use in epilepsy and neuropathic pain, it may also prescribed to help to prevent attacks of migraine. If you have been given it for this reason, then you should speak with your doctor if you have any questions about your treatment.

Gabapentin capsules, tablets, and oral solution are also used to relieve the pain of postherpetic neuralgia (PHN; the burning, stabbing pain or aches that may last for months or years after an attack of shingles).
Gabapentin extended-release tablets (Horizant) are used to treat restless legs syndrome (RLS; a condition that causes discomfort in the legs and a strong urge to move the legs, especially at night and when sitting or lying down).
Gabapentin is in a class of medications called anticonvulsants. Gabapentin treats seizures by decreasing abnormal excitement in the brain. Gabapentin relieves the pain of PHN by changing the way the body senses pain. It is not known exactly how gabapentin works to treat restless legs syndrome.

What is the Off-Label Usages of Gabapentin ?

Gabapentin is in the drug class gamma-aminobutyric acid analogs.
Gabapentin is used to treat the following conditions:
- Alcohol Withdrawal
- Anxiety
- Benign Essential Tremor
- Bipolar Disorder
- Burning Mouth Syndrome
- Carpal Tunnel Syndrome
- Cluster-Tic Syndrome
- Cough
- Diabetic Peripheral Neuropathy
- Epilepsy
- Erythromelalgia
- Fibromyalgia
- Hiccups
- Hot Flashes
- Hyperhidrosis
- Insomnia
- Lhermitte’s Sign
- Migraine
- Nausea/Vomiting, Chemotherapy Induced
- Neuropathic Pain
- Occipital Neuralgia
- Pain
- Periodic Limb Movement Disorder
- Peripheral Neuropathy
- Postherpetic Neuralgia
- Postmenopausal Symptoms
- Primary Orthostatic Tremor
- Pruritus
- Pudendal Neuralgia
- Reflex Sympathetic Dystrophy Syndrome
- Restless Legs Syndrome
- Small Fiber Neuropathy
- Spondylolisthesis
- Syringomyelia
- Transverse Myelitis
- Trigeminal Neuralgia
- Vulvodynia

Gabapentin is Widely Used for Neuropathic Pain and Postherpetic Neuralgia

Postherpetic neuralgia is a painful condition that affects the nerve fibers and skin. It is a complication of shingles, and shingles is a complication of chicken pox.

If the pain caused by shingles continues after the bout of shingles is over, it is known as post-herpetic neuralgia (PHN). It is estimated that about 1 in 5 patients with shingles will go on to have PHN.
Neuralgia is neuropathic pain that occurs along the course of a nerve. It tends to happen when an irritation or damage to a nerve alters its neurological structure or function.
The sensation may be of intense burning or stabbing, and it may feel as if it is shooting along the course of the affected nerve.
Neuropathic pain comes from inside the nervous system. It is not caused by an outside stimulus, such as an injury. People often refer to it as a pinched nerve, or trapped nerve. The nerve itself sends pain messages because it is either faulty or irritated.

Symptoms of Postherpetic Neuralgia

Symptoms are usually limited to the area of skin where the shingles outbreak first occurred and may include:

occasional sharp burning, shooting, jabbing pain
constant burning, throbbing, or aching pain
extreme sensitivity to touch
extreme sensitivity to temperature change
itching
numbness
headaches

In rare cases, if the nerve also controls muscle movement, there may be muscle weakness or paralysis.

Drug Treatments for Postherpetic Neuralgia

[PHN can follow shingles] — Postherpetic neuralgia can cause severe pain in people who have had shingles.

Painkillers: These may include tramadol (Ultram) or oxycodone (OxyContin). There is a small risk of dependency.
Anticonvulsants: The pain of PHN can be lessened with anticonvulsants, because they are effective at calming nerve impulses and stabilizing abnormal electrical activity in the nervous system caused by injured nerves. Gabapentin, or Neurontin, and pregabalin, also known as Lyrica, are commonly prescribed to treat this type of pain.
Steroids: A corticosteroid medication can be injected into the area around the spinal cord. Steroids should not be used until the shingles pustular skin rash has completely disappeared.
Lidocaine skin patches: Lidocaine is a common local anesthetic and antiarrhythmic drug. Applied to the skin, it can relieve itching, burning, and pain from inflammation. The patches can be cut to fit the affected area.
Antidepressants: These affect key brain chemicals, such as serotonin and norepinephrine, which influence how the body interprets pain. Examples of drugs that inhibit the reuptake of serotonin or norepinephrine are tricyclic antidepressants, such as amitriptyline, desipramine (Norpramin), nortriptyline (Pamelor), and duloxetine (Cymbalta).
Gabapentin for neuropathic pain has been found to be very effective when used correctly. Neuropathic pain refers to nerve pain and can be highly debilitating and affect the sufferer’s quality of life significantly. It occurs most commonly in patients with diabetes and after a herpes infection such as shingles. Gabapentin for neuropathic pain is available in most countries by prescription only and may be known by different trade names in different countries, according to manufacturer.
Neuropathic pain, often referred to as postherpetic neuralgia when occurring after a herpes zoster (shingles) infection, occurs due to damage caused to the nerves during the infection. This may result in various symptoms including burning pain, sensitivity to light touch or clothes, itching or numbness and may last for months to years. Treatment is often difficult and may include the use of analgesics, tricyclic antidepressants and antiepileptic drugs, like gabapentin.
Gabapentin is most commonly used to treat some types of epilepsy. It is not fully understood how gabapentin for neuropathic pain works but many studies have shown it to be effective for this indication. Due to the difficulty often experienced in trying to control neuropathic pain, the treating doctor may try different medications from different classes until pain control is achieved. In some cases this may entail the use of numerous medications together.

Treatment for Postherpetic neuralgia

Postherpetic neuralgia is a nerve disease occurs after an attack of herpes zoster infection. Herpes zoster or ‘shingles’ is a viral infection which affects the skin, especially sides of the chest, caused by varicella zoster virus. This is the same virus which causes chicken pox in children.
After an episode of herpes, the virus remains dormant in the nerve tissues of the body. This virus may become active when the immunity of the individual reduces or during convalescence after a major illness, resulting in blisters on the skin, known as shingles. It is accompanied with a rash which disappears without major consequences in about two to four weeks. Around 50% of individuals with shingles go on to develop post herpetic neuralgia (PHN) or after-shingles pain.
The neuralgia begins when the herpetic eruptions begin to heal. The pain appears usually in the affected dermatone or the affected nerve course and results in severe pain in the region which has the same nerve supply. The pain is a drawing, pricking type of intense pain, sometimes accompanied with burning sensation of the skin. The pain lasts from a few weeks to few months, rarely years.

Causes

- - Severe rash within three days of shingles infection
  - A study shows that, 65% of patients were women
  - The chances of developing PHN, increases when the shingles occurs in persons over 50 years.
  - The incidence of herpes zoster is up to 15 times higher in HIV-infected patients than in uninfected persons, and as many as 25 percent of patients with Hodgkin’s lymphoma develop herpes zoster.
  - Blacks are one fourth as likely as whites to develop this condition.
  - Site of HZ involvement
    - Lower risk – Jaw, neck, sacral, and lumbar
    - Moderate risk – Thoracic
    - Highest risk – Trigeminal (especially ophthalmic division), brachial plexus.

Signs and symptoms:

- A pain that continues for 3 months or more, after the healing of shingles, is defined as PHN.
- PHN pain may be burning, aching, itching and sharp and the pain can be constant or it can come and go
- The skin which was affected with blisters, may show scarring
- The involved dermatome may show altered sensations, either hypersensitivity or reduced sensitivity.
- In rare cases, where if the nerves involved also control muscle movement, the patient might also experience muscle weakness, tremor or paralysis

Postherpetic Neuralgia Treatment:

The conventional treatment is directed at pain control while waiting for the condition to resolve. Pain therapy may include multiple interventions, such as topical medications, over-the-counter analgesics, tricyclic antidepressants, anticonvulsants and a number of non medical modalities. Occasionally, narcotics may be required.
When it comes to treating postherpetic neuralgia, you may need to take a combination of medications to effectively manage your pain and other PHN symptoms. No single treatment plan is right for everyone—what medications you take will depend on your PHN symptoms.
While symptoms differ from person to person, for most people, PHN does improve over time. Researchers found that more than half of all patients with PHN stop experiencing pain within one year.¹
Fortunately, during that period of intense pain and other symptoms, there are certain medications that you can take to significantly help control postherpetic neuralgia symptoms.
Before trying a prescription medication, your doctor will most likely want you to try an over-the counter (OTC) analgesic (painkiller) medication, such as acetaminophen or non-steroidal anti-inflammatory drugs (NSAIDs). These medications can help relieve pain and other PHN symptoms.
Tylenol is an example of acetaminophen, and Advil is an example of an NSAID you can take to help treat PHN.
Another OTC medication you may want to try for PHN is capsaicin cream. This cream—made from hot chili pepper seeds—is applied to the affected skin, and it can be helpful for reducing PHN-related pain. But this cream can be painful, so talk to your doctor about how much you should apply.
If these medications aren’t strong enough to treat your PHN symptoms, your doctor may suggest some of the prescription medications below to treat your postherpetic neuralgia.

- Tricyclic antidepressants, such as amitriptyline (Elavil), nortriptyline (Pamelor), and desipramine (Norpramin) are effective at treating postherpetic neuralgia pain. Other classes of antidepressant are also helpful. All classes of antidepressant take a few weeks to start working.
- Anticonvulsants, developed to control seizures, can help reduce the pain of PHN. These include gabapentin (Neurontin), carbamazepine (Tegretol) and pregabalin (Lyrica). Gabapentin enacarbil (Horizant) and gabapentin (Gralise) are approved by the FDA for the treatment of PHN in adults.
- Anti-viral drugs valacyclovir and acyclovir are also becoming medications of choice for treating postherpetic neuralgia.
- Lidocaine Patches for Postherpetic Neuralgia. Lidocaine patches are FDA-approved to treat PHN. The medication in the patch—lidocaine—can penetrate your skin and go to the nerves that are sending the pain signals. A benefit of lidocaine patches is that they don’t numb the skin.
- Prescription capsaicin patches. These patches contain a very high concentration of the chili pepper extract capsaicin. The capsaicin patch Qutenza is applied in a doctor’s office for one hour every three months.

If you have severe pain and other medications don’t work for you, your doctor may want you to try an opioid. Tramadol (eg, Ultram) is an example of a relatively weak opioid that can be used to help you manage PHN. Your doctor may have you try a weaker opioid first. Opioids, such as morphine (MS Contin), oxycodone (OxyContin), and hydrocodone (Vidocin), are also used to treat moderate to severe pain of postherpetic neuralgia.

Homoeopathic Medicine:

Mezereum – For Postherpetic Neuralgia with Intense Burning

Mezereum is rated among the best medicines for postherpetic neuralgia. It is the best-suited prescription when postherpetic neuralgic pains are violent and attended with marked burning. Mezereum is the most helpful among medicines for postherpetic neuralgia in postherpetic pains located in the face. The pain in the face may get worse while eating.
Warmth brings relief. Mezereum is also helpful during active herpes zoster where eruptions are present. The key symptoms to look out for before prescribing Mezereum during herpes zoster infection are violently itching vesicles with shining red areola and intense burning.

2. Ranunculus Bulbosus – For Pains coming in Paroxysms

Another of the prominently indicated medicines for postherpetic neuralgia is Ranunculus Bulbosus. It is indicated for sharp, shooting, postherpetic neuralgic pains that come in paroxysms.
It is also one of the top listed medicines for intercostal neuralgia following herpetic infection. Ranunculus Bulbosus is also indicated for herpes zoster when the vesicles eruptions are bluish in colour. The eruptions are attended with itching and burning symptoms which worsen on contact.

3. Rhus Tox – One of the best Medicines for Postherpetic Neuralgia

Rhus Tox also figures on the list of highly effective medicines for postherpetic neuralgia. It is one of the best medicines for postherpetic neuralgia where the pains are attended with marked restlessness. The skin is sensitive to cold air in such cases. In herpes zoster, Rhus Tox is the most preferred among medicines when the vesicles are yellowish with itching and stinging.

Reviews of Gabapentin for Postherpetic Neuralgia

Gabapentin for the Treatment of Postherpetic Neuralgia

Postherpetic neuralgia (post-hur-PET-ik noo-RAL-juh) is the most common complication of shingles. The condition affects nerve fibers and skin, causing burning pain that lasts long after the rash and blisters of shingles disappear.

The chickenpox (herpes zoster) virus causes shingles. The risk of postherpetic neuralgia increases with age, primarily affecting people older than 60. There’s no cure, but treatments can ease symptoms. For most people, postherpetic neuralgia improves over time.

Symptoms

The signs and symptoms of postherpetic neuralgia are generally limited to the area of your skin where the shingles outbreak first occurred — most commonly in a band around your trunk, usually on one side of your body.

Signs and symptoms might include:

Pain that lasts three months or longer after the shingles rash has healed. The associated pain has been described as burning, sharp and jabbing, or deep and aching.
Sensitivity to light touch. People with the condition often can’t bear even the touch of clothing on the affected skin (allodynia).
Itching and numbness. Less commonly, postherpetic neuralgia can produce an itchy feeling or numbness.

Prevention

The Centers for Disease Control and Prevention (CDC) recommends that adults 50 and older get a Shingrix vaccine to prevent shingles, even if they’ve had shingles or the older vaccine Zostavax. Shingrix is given in two doses, two to six months apart.

The CDC says two doses of Shingrix is more than 90 percent effective in preventing shingles and postherpetic neuralgia. Shingrix is preferred over Zostavax. The effectiveness may be sustained for a longer period of time than Zostavax. Zostavax may still be used sometimes for healthy adults age 60 and older who aren’t allergic to Zostavax and who don’t take immune-suppressing medications.

Gabapentin for the Treatment of Postherpetic Neuralgia

Context.— Postherpetic neuralgia (PHN) is a syndrome of often intractable neuropathic pain following herpes zoster (shingles) that eludes effective treatment in many patients.

Objective.— To determine the efficacy and safety of the anticonvulsant drug gabapentin in reducing PHN pain.

Design.— Multicenter, randomized, double-blind, placebo-controlled, parallel design, 8-week trial conducted from August 1996 through July 1997.

Setting.— Sixteen US outpatient clinical centers.

Participants.— A total of 229 subjects were randomized.

Intervention.— A 4-week titration period to a maximum dosage of 3600 mg/d of gabapentin or matching placebo. Treatment was maintained for another 4 weeks at the maximum tolerated dose. Concomitant tricyclic antidepressants and/or narcotics were continued if therapy was stabilized prior to study entry and remained constant throughout the study.

Main Outcome Measures.— The primary efficacy measure was change in the average daily pain score based on an 11-point Likert scale (0, no pain; 10, worst possible pain) from baseline week to the final week of therapy. Secondary measures included average daily sleep scores, Short-Form McGill Pain Questionnaire (SF-MPQ), Subject Global Impression of Change and investigator-rated Clinical Global Impression of Change, Short Form-36 (SF-36) Quality of Life Questionnaire, and Profile of Mood States (POMS). Safety measures included the frequency and severity of adverse events.

Results.— One hundred thirteen patients received gabapentin, and 89 (78.8%) completed the study; 116 received placebo, and 95 (81.9%) completed the study. By intent-to-treat analysis, subjects receiving gabapentin had a statistically significant reduction in average daily pain score from 6.3 to 4.2 points compared with a change from 6.5 to 6.0 points in subjects randomized to receive placebo (P<.001). Secondary measures of pain as well as changes in pain and sleep interference showed improvement with gabapentin (P<.001). Many measures within the SF-36 and POMS also significantly favored gabapentin (P≤.01). Somnolence, dizziness, ataxia, peripheral edema, and infection were all more frequent in the gabapentin group, but withdrawals were comparable in the 2 groups (15 [13.3%] in the gabapentin group vs 11 [9.5%] in the placebo group).

Conclusions.— Gabapentin is effective in the treatment of pain and sleep interference associated with PHN. Mood and quality of life also improve with gabapentin therapy.

Gabapentin for Postherpetic Neuralgia Comment

The results of our study clearly show that gabapentin reduces PHN pain compared with placebo. This was demonstrated on several measures of pain and as assessed by subjects as well as investigators. For the primary outcome variable, change in average daily pain score, the actual calculated power of the study in demonstrating the predicted level of efficacy of gabapentin approached 100%. In addition, several secondary outcome measures also showed gabapentin as superior to placebo. Sleep, several quality-of-life measures, and several mood state variables were significantly improved by gabapentin therapy. Significant improvement was evident during the titration phase (at the 2-week time period) and continued to accrue over the course of 8 weeks of treatment. Adverse effects of gabapentin were minor and well tolerated, consisting primarily of somnolence and dizziness. These 2 adverse effects accounted for most of the adverse event–related withdrawals. Despite doses of gabapentin up to 3600 mg/d in a population with an average age of 73 years, no serious drug-related adverse events were reported. In clinical practice, adverse effects such as these can be managed by a slower upward titration, dose reduction, and use of lower maximum doses than allowed in the clinical trial protocol. Serious adverse events, especially of a cardiovascular nature, were not evident. Overall, gabapentin reduced PHN pain with a very acceptable adverse effect profile.

The mechanism of action of gabapentin remains uncertain. Spinal cord neuronal calcium channels play a potentially important role in chronic neuropathic pain and are modulated by gabapentin. Analgesia through GABAergic neurotransmission effects is much less certain. Despite the uncertainty regarding the mechanism of action of gabapentin, the drug has been shown effective in rat models of chronic neuropathic pain.²²^-25 Results of treatment of PHN can likely be predicted by testing in preclinical neuropathic pain models because PHN is not only common, but has consistent symptomatology, a clear cause, and consistent neuropathology.

The current standard of treatment for PHN with oral medications are the TCAs. Nontricyclic antidepressants with better adverse effect and safety profiles, including the selective serotonin reuptake inhibitors, have not been proven equivalent to TCAs in terms of efficacy.¹⁶ In the elderly population afflicted with PHN, therapy with TCAs is frequently either contraindicated (usually for cardiovascular reasons) or poorly tolerated because of excessive sedation, cognitive impairment, dry mouth, constipation, sexual dysfunction, and orthostatic lightheadedness. Other approaches with good safety and evidence of efficacy, such as topical local anesthetics and topical aspirin-nonsteroidal anti-inflammatory agents, are either unproven in long-term use or not commercially available.² Topical capsaicin produces a modest improvement in pain after long-term use, but has a high rate of burning sensations that are unacceptably severe.¹ Opioids are frequently used to treat PHN in clinical practice, but do not yet have adequate support from placebo-controlled studies of long-term use. Many of the problematic adverse effects of TCAs also pertain to the use of opioids, such as sedation, cognitive impairment, and constipation. In addition, many patients and physicians are reluctant to use medications that carry the stigma of being addicting, despite the lack of evidence that this is a problem in the PHN population.

From the safety and efficacy evidence in our study, a strong case can be made for considering gabapentin as a first-line oral medication for management of PHN pain. There are no studies directly comparing gabapentin with TCAs. From published systematic reviews of antidepressants and anticonvulsants for neuropathic pain by McQuay et al,³² comparisons of safety and efficacy can be made by calculating the number needed to treat (NNT) for both parameters. The NNT is the reciprocal of the difference in the percentage of patients improved or harmed by active therapy compared with control therapy, expressed for benefit as 1/[(% improved active)−(% improved placebo)]. For placebo-controlled TCA studies of PHN pain, the NNT for benefit ranged from 1.9 to 4.1; for minor adverse events, the NNT ranged from 1.7 to 8.8; and for adverse events leading to study withdrawal, the NNT ranged from 13 to 37. From the data in Figure 4 and the text, the gabapentin NNT for benefit is 3.2, the NNT for minor adverse events is 3.7, and the NNT for adverse events leading to study withdrawal is 25. From this perspective, gabapentin should be considered at least as effective as TCAs, at least as safe, and with fewer contraindications to use.

Tricyclic antidepressants and opioids each have a different mechanism of action than gabapentin. Tricyclic antidepressants may relieve pain through serotonin and norepinephrine reuptake blockade, by blockade of α-adrenergic receptors, by sodium channel-blocking effects, and by relief of depression. Opioids relieve pain through activation of a family of specific receptors found in both the central and peripheral nervous systems.

Because of its straightforward pharmacokinetics and relative lack of adverse drug interactions, multidrug regimens to control chronic neuropathic pain can include gabapentin if gabapentin monotherapy fails. In summary, based on the results of this 8-week study, gabapentin can be added to the list of first-line medications for treatment of chronic neuropathic pain syndromes such as PHN.