Many medications are used in the treatment of pain. The most common pain medications include opioids, anti-inflammatories, simple analgesics, and others. Read our previous blog for more detailed information on these common pain medications.
For many patients, these common pain medications are not effective and specialized medications are often used. These uncommon medications include seizure medications, antidepressants, and a variety of others. These drugs are often considered neuropathic medications and are used whenever abnormal nerve function is suspected in causing pain. Read on for more detailed information about these uncommon pain meds and how they’re used in the treatment of pain.
Antidepressant Medications
Antidepressant medications are used to control neuropathic pain. Two types of antidepressants are commonly used:
- Tri-cyclic antidepressants (TCAs). Tricyclic antidepressants include amitriptyline, Nortriptyline, and desipramine, the later two are the best tolerated and used at very low dose. The TCAs have many side affects including dry mouth, low blood pressure, sedation, and urinary problems.
- Serotonin/noradrenaline reuptake inhibitors (SNRIs). The newer SNRIs include Cymbalta and Savella have very few side affects. Cymbalta is very effective in a number of neuropathic pain situations including diabetes, radiculopathy and fibromyalgia, while Savella only is known to work in fibromyalgia.
Antidepressants such as Zoloft, Prozac, and Celexa along with Effexor have no affect on pain. These medications decrease nerve transmission and nerve sensitivity.
Seizure Medications
Seizure medications were among the first neuropathic medications. The originals were Dilantin and Depakote, but due to their significant side affects, these are now rarely used. Tegretol is also used rarely for similar reasons, but has been found uniquely helpful with trigeminal neuralgia.
All seizure medications work by decreasing the ability of the nerves to be active and send signals. They can be sedating and can cause mental clouding. The newer ones include gabapentin (Neurontin) and Lyrica. For any pain nerve associated, these medications can be very effective, and if monitored and prescribed correctly have minimal side effects.
Lidocaine Skin Patches
Lidocaine skin patches use a local anesthetic to decrease nerve sensitivity at the skin. These patches work on a variety of painful conditions including shingles (post-herpetic neuropathy), and diabetic neuropathy. They may be helpful in headaches, neck and low back pain. Myofascial pain and fibromyalgia sometimes respond to lidocaine skin patches as well.
Clonidine & Tizanidine (Zanaflex)
Clonidine and tizanidine (Zanaflex) are alpha-2 adrenergic agonists, blocking certain sensory interneurons important in pain transmission. Clonidine is normally a potent blood pressure medication, but sometimes is very effective in neuropathic pain and is sometimes even used in intrathecal pumps. Tizanidine has properties that help with analgesia in neuropathic pain and helps with muscle spasms, and was originally developed for controlling muscle spasm in quadriplegia.
Capsaicin & Baclofen
Capsaicin is a crème derived from chili peppers used in neuropathic diabetic pain and post-herpetic neuralgia. It activates certain pain fibers on the skin.
Baclofen is an unusual medication affecting nerve receptors in the spinal cord and brainstem. Originally, it has been for spasticity, often in paraplegia, quadriplegia, cerebral palsy, and multiple sclerosis. It is used orally as pills and sometimes by intrathecal pump. It can help also with neuropathic pain.
NMDA Receptor Antagonists
A final group of adjuvant pain medications are NMDA receptor antagonists. These medications also block a set of sensory fibers and pain transmission. Ketamine is the main drug in this category. It can only be given by IV or intrathecal pump, and has been used in CRPS, and cancer. It is similar to the drug LSD, and can cause hallucinations.