Painkillers for Acute and Chronic Pain

by admin | March 26, 2022 6:30 am

Pain is one of the most common and immediate outcomes of several ailments and health conditions. The pain can be very intense but in short bursts (acute pain) or it could be low-intensity but long-term pain (chronic pain). Minimizing pain is as important as addressing the underlying condition in order to increase patient comfort and accelerate recovery. And this is effectively handled by a class of medicines called Painkillers. Painkillers have their own side-effects, so the patient will be informed of the same so that there are no surprises.

Depending on the delivery mechanism, Painkillers are of 3 types: (a) oral medication that is swallowed, chewed or drunk, (b) topical creams, gels and lotions that are applied on the body at the affected area (c) injections that are given directly to concerned areas of the body. The 3^rd category – injections – directly target those nerves that carry pain messages, which is why they are called Nerve-block injections. For the purpose of this article, we are combining the first two classes of Painkillers.

A. Oral and Topical Painkillers

NSAIDs

Non-steroidal anti-inflammatory drugs (NSAIDs) are used when there is mild or moderate pain, along with swelling and inflammation. There are a certain class of enzymes called cyclooxygenase (COX) that are released when there is tissue damage, pain and inflammation. NSAIDs block some of these enzymes and help reduce inflammation and pain. They are used in treating pain caused by arthritis, back and neck pain, menstrual cramps, muscle sprains and muscle strains. Side-effects include stomach pain, stomach bleeding, ulcers[1], nausea, kidney damage, high BP and fluid retention.

Acetaminophen

Acetaminophen is quite popular in overcoming pain in the bones and muscles, as well as arthritic pain. The mechanism for pain-relief is unknown but they could possibly block a COX-3 enzyme. When used for a long period or in high doses, they can cause kidney damage, bleeding, gastric ulcers and liver failure[2].

COX-2 Inhibitors

While NSAIDs block the entire class of COX enzymes, COX-2 inhibitors only block COX-2 enzymes. Similar to NSAIDs, they are used to treat pain caused by arthritis, back pain, neck pain, menstrual cramps, muscle sprains and muscle strains. However, they do not cause the stomach-related side-effects which is common with NSAIDs. Side-effects include high blood pressure, fluid retention and kidney damage.

Anti-depressants

As the name implies, these medicines are generally given to combat depression. However, when given in small doses, they can address nerve-related pain in conditions like diabetic neuropathy[3], back pain and fibromyalgia. These interfere with certain chemical processes that cause the pain sensation. Examples of these drugs include tricyclic anti-depressants, sodium channel blocking medicines and serotonin norepinephrine reuptake inhibitors (SNRIs). These medicines are prescribed in low doses and must be taken continuously whether one has pain or not. Patients with glaucoma will not be given this. Side-effects include sleepiness and dry mouth. However, the doctor will give tips on overcoming these side-effects.

Anti-convulsants

As the name implies, these medicines are generally given to prevent convulsions or seizures caused by epilepsy or another neurological condition. However, they can also address burning or shooting pain (acute pain) in conditions such as postherpetic neuralgia and diabetic neuropathy. These work by quietening the pain signals from damaged nerves. These must be taken continuously whether one has pain or not. Patients with kidney stones, kidney disease and glaucoma are not given this. Side-effects include drowsiness, weight-gain and abdominal pain.

Muscle-relaxants

These are given for people who suffer from painful muscle spasms. Side-effects are mild, which includes drowsiness and dizziness.

Opioids

These are synthetic versions of opium and drugs derived from opium such as heroin and morphine. They are used to treat acute pain caused by injuries such as bone fracture, or surgery. These work by activating feel-good neurotransmitters called endorphins, which suppress pain and give positive feelings. They are useful in providing immense relief during short periods of severe pain such as 2-3 days. The only problem with opioids is that, soon the person becomes dependent or addicted to them. This increases the risk of misuse and long-term addiction.

B. Painkiller Injections

These are generally outpatient procedures carried out by a Pain Management specialist, with the help of a fluoroscope (X-ray) or ultrasound, and a computer monitor, to guide the specialist’s moves. A contrast dye is used sometimes, in order to highlight the affected areas on the computer screen. People who are allergic to such dyes and pregnant women are advised against such procedures. Such patients should inform the doctor in advance, so that he/she can explore alternate solutions.

Epidural Steroid Injection 

The epidural space is an area inside the vertebral canal and is between the canal and the spinal cord. It consists of lymphatics, adipose tissue, spinal nerve roots, a network of internal vertebral venous plexuses, loose connective tissue, dural venous sinuses and small arteries. In patients suffering from neck pain, back pain or pain in the hands and legs, an anti-inflammatory steroidal medicine is injected into the epidural space close to the location of pain. Side-effects include a soreness in the neck, back or limbs at the point where the needle enters the skin. Other side-effects include numbness and weakness for 8 to 10 hours after the procedure.

Facet-joint Application

Facet joints lie at the junction of the vertebrae and the spinal column. They help stabilize the spine in the neck and back. In patients suffering from neck or back pain, it is important to understand what is causing the pain. To achieve this, a nerve-blocking injection is injected into a facet-joint in the back or neck. A needle is pushed into the skin, and then the doctor uses X-ray visualization to precisely move the needle to the level of the joint. Side-effects include soreness at the point of ingress of the needle.

Lumbar Sympathetic Block

Complex Regional Pain Syndrome (CRPS) is a rare condition characterized by chronic pain in an arm or a leg. It typically develops after an injury, heart-attack, stroke or surgery. The lumbar region of the spinal column refers to the lower back and consists of 5 vertebrae named L1 to L5. In people with CPRS, a local anesthesia-like painkiller is injected into the body of the vertebra, especially L2 or L3, to one side of the affected area where the ganglion (a cluster of nerves in the peripheral nervous system) is located. The doctor will use X-rays and contrast dye to position the needle precisely. Side-effects include soreness at the point of ingress of the needle in the skin, and numbness that lasts 8 to 10 hours.

Celiac Plexus Block

The Celiac Plexus, also called Solar Plexus is a bundle of nerves that lies in the abdomen, behind the pancreas and close to the aorta. These nerves send signals to the brain and spinal cord from organs of the digestive system. In patients with chronic abdominal pain, or pain due to cancer, it is important to numb the pain. This is done in 2 steps. The needle is placed in the back at the level of the solar plexus. Firstly, a diagnostic painkiller injection is given in one or more iterations to see where the pain is originating from. Once this is located, in the 2^nd step, a pain-numbing medicine is injected into the precise area. The doctor will use X-rays and contrast dye to guide his/her movements. Side-effects include soreness and numbness for a few hours.

Stellate Ganglion Block

Stellate ganglion is a bundle of nerves pertaining to the sympathetic nervous system, located in the neck, on either side of the larynx or voice box. In people suffering from CPRS (mentioned above), or pain in the head, neck, upper arm and upper chest, a stellate ganglion block injection is given to numb the pain. The injection is given in the neck area at the level of the stellate ganglion. The doctor may use ultrasound, or a combination of X-ray and contrast dye to guide his/her movements. Side-effects include soreness at the point of ingress of the needle, droopy eyelids, stuffy nose, difficulty in swallowing and hoarseness of the voice.

Foraminal injections

Conditions like sciatica and herniated discs cause severe pain and inflammation in the lower back, legs and/or feet. To alleviate this pain, foraminal, also called transforaminal injections are given. Intervertebral foramen or neural foramen are openings between the vertebrae. Here, the nerve-endings leave the spinal cord and travel to other parts of the body such as legs and feet, carrying signals between brain and rest of the body. During this procedure, a steroidal anti-inflammatory drug is given to numb the pain. The procedure is done in 2 steps as mentioned earlier. In the 1^st step, one or more injections locate the precise spot of the pain. In the 2^nd step, a local anesthesia-like-painkiller is given to numb the pain. Side-effects include numbness in the limbs, headache and dizziness.

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Reviewed by Dr Suresh S Venkita, Group Medical Director, Kauvery Hospitals

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Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

Chennai – 044 4000 6000 • Trichy – Cantonment – 0431 4077777 • Trichy – Heartcity – 0431 4003500 • Trichy – Tennur – 0431 4022555 • Hosur – 04344 272727 • Salem – 0427 2677777 • Tirunelveli – 0462 4006000 • Bengaluru – 080 6801 6801

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NOTE: Take medications only when prescribed by your doctors, self-medication must be avoided under any circumstances.

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