What are the characteristics of pregabalin?📄📄📄

Pregabalin is a drug used to treat neuropathic pain. Clinically, it is widely used to treat post-herpetic neuralgia, neuralgia caused by diabetic neuropathy, etc.

What are the clinical indications for pregabalin?

Pregabalin is clinically approved for the treatment of diabetic peripheral neuropathy, fibromyalgia, neuralgia associated with spinal cord injury, partial seizures in certain adults with epilepsy, and postherpetic neuralgia. In addition, it will also be used to treat postoperative or post-traumatic neuropathic pain, tumor-related neuropathic pain, and chemotherapy-related neuropathic pain.

What is the mechanism of action of pregabalin?

Clinically, it is believed that changes in calcium ion channels in the nervous system are related to neuropathic pain. Calcium ion channels are composed of four subunits: α1, α2-δ, β, and γ. Pregabalin binds to the α2-δ subunit of calcium channels in the nervous system. It inhibits neuronal presynaptic membrane Ca2+ influx. This reduces the release of excitatory neurotransmitters (such as calcitonin, glutamate, substance P, etc.), thereby controlling pain. 

What is the dosage of pregabalin?

Oral pregabalin mainly comes in regular dosage forms and sustained-release dosage forms.

Common oral dosage forms of pregabalin: It is generally taken two to three times daily, with or without food.

Treatment of postherpetic neuralgia and diabetic peripheral neuropathic pain:

• Initial dose: 150 mg orally daily in two to three divided doses.
• Adjust the dose: According to the drug's efficacy and the patient's tolerance, it can be increased to 300 mg orally daily within one week, taken in two to three times. If the patient takes 300 mg daily, the pain symptoms cannot be fully relieved after two to four weeks and the patient can tolerate pregabalin. The dose can be increased to 600 mg orally daily in two to three divided doses.

Treating fibromyalgia:

• Initial dose: 75 mg orally twice daily.
• Adjust the dose: It can be increased to 150 mg twice daily (300 mg/d) within a week based on the efficacy of the drug and the patient's tolerance. If the patient does not have sufficient efficacy even if taking 300 mg daily, the dosage can be increased to 225 mg twice daily (450 mg/d). However, it is considered that the adverse effects of pregabalin are dose-dependent, so the dose exceeding 450 mg/d is not recommended.

Sustained-release preparation: Take once daily orally after dinner. 

Pregabalin is mainly absorbed in the upper small intestine and its sustained-release dosage forms generally use a material that floats in the stomach as a backbone. After dinner, the gastric pylorus closes better and the gastric emptying rate slows down. Therefore, taking the extended-release form of pregabalin after dinner may increase its retention and release time in the stomach. It promotes drug absorption and improves bioavailability. Additionally, patients often experience more severe pain symptoms at night. Therefore, patients will have better analgesic effects if they take the medicine at night. Drowsiness and dizziness are the most common adverse reactions of pregabalin. Therefore, by the time a patient takes pregabalin in the evening and its drug levels reach peak levels, the patient will already be less active or sleeping. This increases patient tolerance and compliance with the medication.

What are the adverse reactions of pregabalin?

The most common adverse reactions are drowsiness and dizziness. Common ones include increased appetite (weight gain), blurred vision, conjunctivitis, disorientation, ecchymosis, abnormal gait, loss of libido, joint pain, leg cramps, myalgia, nasopharyngitis, etc. Some patients with diabetes may need to adjust the dose of their antidiabetic medications because they gain weight while taking pregabalin. If the patient develops angioedema, he should stop taking the drug immediately and seek medical treatment promptly. Patients should inform their doctor as soon as possible if they develop unexplained muscle pain, tenderness, or weakness (especially if these muscle symptoms are accompanied by general malaise or fever) and visual changes.

After short-term or long-term treatment with pregabalin, some patients may experience withdrawal symptoms after stopping the drug. Therefore, if a patient needs to discontinue pregabalin, it is recommended that the dose be tapered over at least one week. Patients should abstain from alcohol while taking pregabalin.