What is the Difference Between Gabapentin and Pregabalin

The key difference between Gabapentin and Pregabalin is that Gabapentin takes 3 hours to reach the peak plasma concentration after oral administration, while Pregabalin is more potent since it absorbs faster and reaches peak plasma concentration within one hour after oral administration.

Gabapentin and Pregabalin are anticonvulsants used to treat various conditions, including seizures, neuropathic pain, and anxiety disorders. They are structural analogues to the neurotransmitter inhibitor gamma amino butyric acid (GABA). However, they do not bind to GABA or benzodiazepine receptors; instead, they bind to the α2δ1 subunit of voltage-gated calcium channels. The mechanism of action of both Gabapentin and Pregabalin is associated with inhibiting excitatory neurotransmitters in the presynaptic membrane. Both drugs are well tolerated but should be prescribed by a doctor. Ultimately, the best choice of medication depends on individual needs and preferences.

CONTENTS

1. Overview and Key Difference
2. What is Gabapentin 
3. What is Pregabalin
4. Similarities – Gabapentin and Pregabalin
5. Gabapentin vs. Pregabalin in Tabular Form
6. Summary – Gabapentin vs. Pregabalin

What is Gabapentin?

Gabapentin is an anticonvulsive medication approved by FDA in 1993. Originally, it was used as a muscle relaxant and anti-spasmodic medication. Currently, Gabapentin is prescribed for seizures, neuropathic pain, neuralgia, and partial-onset seizures. Furthermore, it is also prescribed for certain psychological conditions such as bipolar disorder, anxiety, resistant depressants, and mood disorder. Gabapentin is a structural analogue of the neurotransmitter inhibitor GABA and is known to cross the blood-brain barrier freely. Despite its structural similarity to GABA, it does not promote the synthesis and uptake of GABA. Gabapentin displays a high affinity for α2δ1, a voltage-gated calcium channel, thereby inhibiting the release of excitatory neurotransmitters in the presynaptic area. Furthermore, Gabapentin is known to promote the plasma concentration of serotonin.

Orally administered Gabapentin is absorbed in the intestine via facilitated transport by the L-type amino acid transporter 1 (LAT1). Interestingly, the oral bioavailability of Gabapentin is inversely proportionate to the dose, while no food effect has been identified for the absorption and bioavailability. Upon absorption, less than 3% of the drug remains bound with the plasma protein and does not undergo significant metabolism. Unchanged Gabapentin is eliminated in the urine with an elimination half-life of 5-7 hours. An overdose of Gabapentin is associated with dizziness, drowsiness, lethargy, and gastrointestinal symptoms such as diarrhea. Commonly found brand names of Gabapentin include Gralise and Neurontin.

What is Pregabalin?

Pregabalin is a medication used to treat neuropathic pain, seizures, and anxiety disorders. It is also structurally similar to GABA but does not bind with GABA or other benzodiazepine receptors. It binds to the α2δ1 subunit and inhibits excitatory neurotransmitters, reducing abnormal electrical activity in the brain. However, there is no evidence related to the effect of Pregabalin on dopamine, serotonin, and opiate receptors. Pfizer markets pregabalin under the brand name Lyrica. It is also available as an extended-release formula known as Lyrica Cr.

Orally administered Pregabalin reaches above 90% of the bioavailability 1 hour after oral administration. The absorption is faster when taken in the fasted state. However, Pregabalin is not very lipophilic; it can cross the blood-brain barrier through LAT1. Minor levels of Pregabalin are metabolized in the liver and exclusively excreted in urine with an elimination half-life of 6 hours. Pregabalin may cause severe allergic reactions such as hives, blisters, trouble breathing, and swelling of the face, mouth, and throat. In addition, the overdose of Pregabalin includes somnolence, restlessness, confusion, depression, agitation, and affective disorder.

What are the Similarities Between Gabapentin and Pregabalin?

• Gabapentin and Pregabalin are anticonvulsant medications.
• They treat various conditions, including seizures, neuropathic pain, and anxiety disorders.
• Both are structural analogues to the GABA.
• They bind to the α2δ1 subunit of voltage-gated calcium channels.
• They can cross the blood-brain barrier.

What is the Difference Between Gabapentin and Pregabalin?

Gabapentin and Pregabalin are anticonvulsants commonly used to treat seizures and nerve pain. The key difference between Gabapentin and Pregabalin is that Gabapentin takes 3 hours to reach the peak plasma concentration after oral administration, while Pregabalin is more potent since it absorbs faster and reaches peak plasma concentration within one hour after oral administration. Furthermore, the onset of action is much faster in Pregabalin than in Gabapentin. Gabapentin is more likely to cause side effects such as difficulty speaking, increased risk of viral infections, fever, and unusual eye movements. On the other hand, Pregabalin is more likely to cause side effects such as dry mouth, constipation, breast enlargement, weight gain, and swelling. It is important to note that Gabapentin tends to have a higher risk of addiction compared to Pregabalin. Therefore, when making decisions for individual cases, it’s important to consider all relevant differences.

The infographic below presents the differences between Gabapentin and Pregabalin in tabular form for side-by-side comparison.

Summary – Gabapentin vs. Pregabalin

Gabapentin and Pregabalin are anticonvulsant medications frequently prescribed to manage seizures and alleviate nerve pain. The key difference between Gabapentin and Pregabalin lies in their absorption and potency. Gabapentin takes approximately 3 hours to reach peak plasma concentration after oral administration. Pregabalin is more potent, absorbing faster and reaching peak plasma concentration within just one hour. Additionally, Pregabalin has a faster onset of action compared to Gabapentin. Although these medications share similarities in their mechanism of action and usage, they exhibit differences in side effects and addiction potential. Therefore, the difference between Gabapentin and Pregabalin should be carefully considered before prescriptions.

Reference:

1. Mao, Jianren, and Lucy L. Chen. “Gabapentin in pain management.” Anesthesia & Analgesia, vol. 91, no. 3, 2000, pp. 680–687.
2. Ben-Menachem, Elinor. “Pregabalin pharmacology and its relevance to clinical practice.” Epilepsia, vol. 45, no. s6, 2004, pp. 13–18.

Image Courtesy:

1. “Gabapentin2DACS” By Fuse809 (talk) – Own work (Public Domain) via Commons Wikimedia
2. “Pregabalin” By Harbin – Own work (Public Domain) via Commons Wikimedia