Pregabalin

• 1. Introduction

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  Pregabalin, sold as Lyrica and under a long list of other brand names, once helped set a spending record for a single drug. In January 2016, its maker Pfizer put $24.6 million into television advertising for it in one month. That is more than any other single drug had ever received.

  The pill behind the ads is a small molecule with an odd pedigree. It was built to imitate a chemical in the brain, yet it turned out not to touch that chemical's receptors at all. It treats seizures, nerve pain and anxiety, three conditions that rarely share a medicine cabinet.

  This documentary asks how a university laboratory experiment grew into a global product. It asks what the drug really does inside the body, given that its original theory was wrong. And it asks why regulators in the United Kingdom, Australia and the United States each decided that this popular prescription deserved tighter control.

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• 2. A Wrong Theory, A Right Drug

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  In Evanston, Illinois, at Northwestern University, the medicinal chemist Richard Bruce Silverman was chasing an idea. He wanted a successor to gabapentin, an existing seizure medicine. Pregabalin was first synthesized there in 1990.

  Between 1988 and 1990, a visiting research fellow named Ryszard Andruszkiewicz made a series of molecules that Silverman had requested. Collaborators at Parke-Davis Pharmaceuticals tested them in mouse seizure models. One compound looked especially promising.

  In a test tube, that compound switched on an enzyme called L-glutamic acid decarboxylase. Silverman had hoped the enzyme would raise production of GABA, the brain's main inhibitory messenger, and so block convulsions. That explanation later proved unimportant to how the drug prevents seizures.

  Parke-Davis then ran extensive development studies and clinical trials. The drug won approval in the European Union in 2004. The United States followed in December 2004 for epilepsy, diabetic nerve pain and the nerve pain that can follow shingles. It reached American pharmacies under the name Lyrica in the fall of 2005.

  Making the molecule at scale took its own invention. Hoekstra and colleagues at Warner-Lambert reported the first manufacturing process in 1997, under the investigational name CI-1008. It started from a racemic mixture and separated the useful mirror-image form using (S)-(+)-mandelic acid.

  A cleaner route came from Burk and colleagues, who used a rhodium catalyst to build the correct shape directly. In 2008, Pfizer reported a second-generation process that used a lipase enzyme from the fungus Thermomyces lanuginosus, sold commercially as Lipolase by Novozymes.

  In 2021, Dr. Reddy's Laboratories reported a generic route that combined continuous-flow chemistry with an organocatalytic reaction. Meanwhile, in 2017, the FDA approved an extended-release version called Lyrica CR, though without the fibromyalgia and add-on seizure uses of the original.

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• 3. Not Quite GABA

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  The protein called alpha-2-delta-1 sits at the center of how pregabalin works. It was first described as a helper part of voltage-gated calcium channels, the gates that let calcium enter nerve cells.

  Pregabalin looks like GABA on paper, and it belongs to the class called gabapentinoids. Yet it is inactive at GABA receptors. It does not turn into GABA in the body, and it does not alter how GABA is transported or broken down.

  Instead, it binds to alpha-2-delta-1 and cuts the release of excitatory messengers at synapses. These include glutamate, norepinephrine, serotonin, dopamine, substance P and calcitonin gene-related peptide. Quieting those signals reduces overactive networks of neurons, which is how relief from pain, seizures and anxiety is thought to arrive.

  It is not a calcium channel blocker in the usual sense. It does not bind the pore-forming part of the channel, called alpha-1. Laboratory studies show it instead reduces the traffic of channels from inside the cell to the membrane, where they work.

  There are two alpha-2-delta subunits that bind these drugs, labeled 1 and 2. Pregabalin shows similar affinity for both. In animal models of pain, seizures and anxiety, its effects require binding to alpha-2-delta-1.

  Researchers have also found that this protein, independent of calcium channels, associates with certain NMDA and AMPA glutamate receptors. It also associates with the extracellular matrix protein thrombospondin. This has been proposed as part of the pain-relieving effect.

  The chemistry hints at a stranger story. Pregabalin is (S)-(+)-3-isobutyl-GABA, but it also closely resembles the amino acids L-leucine and L-isoleucine. Those two bind the same subunit with similar affinity, at an IC50 of 71 nM for L-isoleucine.

  Both amino acids are present in human cerebrospinal fluid at micromolar levels: 12.9 micromolar for L-leucine and 4.8 for L-isoleucine. That may explain a puzzle. The drugs bind in the nanomolar range, yet work in the body only in the low micromolar range, perhaps because natural amino acids compete for the site.

  Comparisons with gabapentin vary. One study found six-fold higher affinity for pregabalin. Another measured nearly equal values, with Ki of 32 nM for pregabalin and 40 nM for gabapentin. As an analgesic, pregabalin is 2 to 4 times more potent, and in animals 3 to 10 times more potent as an anticonvulsant.

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• 4. Through the Body

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  Fewer than ten drugs are known to ride the large neutral amino acid transporter 1, also called LAT1 or SLC7A5. Pregabalin is one of them. It is absorbed from the intestine through this carrier, which normally moves amino acids such as L-leucine and L-phenylalanine.

  Gabapentin depends only on LAT1, and that carrier saturates easily. Higher doses of gabapentin therefore absorb poorly. Pregabalin also uses other carriers and shows steady, proportional absorption with no saturation.

  Oral bioavailability is at least 90% across the whole clinical range of 75 to 600 mg per day. Food does not change how much is absorbed, but it changes the timing. Peak levels arrive at about 0.6 hours when fasting and 3.2 hours after a meal, a five-fold difference, and the peak itself is 25-31% lower.

  The same transporter carries pregabalin into the brain. Because the molecule has low lipophilicity, it cannot slip across the blood-brain barrier on its own. LAT1 is highly expressed there. The volume of distribution in humans is about 0.56 liters per kilogram, and less than 1% binds to plasma proteins.

  In rats, the drug crosses the placenta and appears in milk. In people, it undergoes little or no metabolism. Radioactivity studies found that about 98% of what appeared in urine was unchanged pregabalin, with N-methylpregabalin as the main metabolite. It is generally safe in liver cirrhosis.

  The kidneys do the work of removal, at a clearance of 73 mL per minute. The reported half-life is 6.3 hours, which is why doses are taken 2 to 3 times per day. Because clearance tracks kidney function, people with a creatinine clearance below 60 mL per minute need lower doses.

  Dialysis changes the arithmetic again. A standard four-hour hemodialysis session lowers blood levels by roughly half, so a supplemental dose follows each session.

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• 5. What It Treats

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  In drug-resistant focal epilepsy, pregabalin is used as an add-on to other treatments. Taken alone, it works less well than some other seizure medicines. How it compares with gabapentin for seizures remains unclear.

  Nerve pain is where the evidence looks strongest. The European Federation of Neurological Societies recommends pregabalin as a first-line agent for pain from diabetic neuropathy, post-herpetic neuralgia and central neuropathic pain. A minority of patients gain substantial benefit, and a larger group gain moderate benefit.

  It carries equal weight with gabapentin and tricyclic antidepressants, though as of 2010 the antidepressants cost less. It relieves pain about as well as duloxetine and amitriptyline. Combining it with either of those two adds relief for people who are not controlled on one drug, and is considered safe. Higher doses are associated with greater effect.

  Its role in cancer-related nerve pain is controversial, though common. Its use to prevent chronic pain after surgery is also disputed. For acute pain, it is generally not regarded as effective. In trials of acute pain after surgery, overall pain scores did not change, but people needed less morphine and had fewer opioid side effects.

  For generalized anxiety disorder, the picture is different. Effects appear within one week and match those of lorazepam, alprazolam and bromazepam. Pregabalin produced more consistent relief of the bodily symptoms of anxiety. Long-term trials showed no tolerance, and unlike benzodiazepines it enhances slow-wave sleep and causes milder cognitive and movement impairment.

  The World Federation of Biological Psychiatry lists it as one of several first-line choices for generalized anxiety disorder. For obsessive-compulsive disorder and post-traumatic stress disorder it points to SSRIs instead, though pregabalin seems helpful as a complement in PTSD.

  Several off-label uses lack support. There is no evidence of benefit in bipolar disorder or migraine prevention. For sciatica and low back pain there is no evidence and significant risk. A 2025 review did find possible gains in sleep quality among people with fibromyalgia.

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• 6. When It Goes Wrong

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  Dizziness and drowsiness strike more than 10% of the people who take pregabalin. Common effects, in 1-10% of users, include blurred vision, swelling in the legs, increased appetite with weight gain, euphoria, confusion, vivid dreams and memory trouble. Its profile resembles other central nervous system depressants.

  Rare effects, below 0.1%, include pancreatitis, low white blood cell counts and suicidal thoughts or behavior. Though it is both a depressant and an anticonvulsant, it can paradoxically cause seizures, particularly in large overdoses.

  A systematic review pooled five cohort studies covering 1,085,488 patients. It linked gabapentinoids to blood clots in the legs and lungs as early as three months into use. Cardiovascular events rose with use beyond a year. Heart failure did not increase.

  Stopping abruptly is its own hazard. Some people reported symptoms suggesting physical dependence, including insomnia, headache, heart palpitations, nausea, anxiety, flu-like illness, major depression, seizures and muscle twitching. The FDA judged its dependence profile on a withdrawal checklist to be lower than that of benzodiazepines.

  The Lyrica package insert recommends tapering over at least one week. Best Practice Advocacy Centre New Zealand and NHS Somerset advise a much slower withdrawal.

  Overdose brings severe drowsiness, loss of coordination, slurred speech, anxiety and uncontrollable jerking. One case study reported macular detachment. Overdose is usually not fatal unless mixed with another depressant. Several people with kidney failure developed jerking movements as the drug slowly accumulated.

  Mixing is where the danger concentrates. In December 2019, the FDA warned of serious breathing problems with gabapentin or pregabalin, especially for people with lung disease or those also taking other central nervous system depressants. Among 49 case reports from 2012 to 2017, twelve people died of respiratory depression, and each had at least one risk factor.

  The agency weighed two randomized trials in healthy people, three observational studies and animal work. One trial showed pregabalin alone, and with an opioid, can depress breathing. The observational studies tied gabapentinoids before surgery to breathing trouble afterward. The FDA required new warnings and asked manufacturers to study abuse potential alongside opioids.

  A 2020 study in the British Journal of Anaesthesia looked at gabapentinoid prescribing in Scotland. Among recurrent users, benzodiazepines were co-prescribed in 26.8% of cases and opioids in 49.9%, with both in another 17.1%. The age-standardised death rate for people prescribed these drugs was double that of the general Scottish population.

  A 2022 meta-analysis reached a similar caution about opioid combinations. Alcohol compounds impairment, so the prescribing information advises against drinking. Pregabalin may also raise angioedema risk, especially with ACE inhibitors, and may worsen fluid retention from thiazolidinedione diabetes drugs.

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• 7. Laws Around the World

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  About 4% of users in clinical trials reported euphoria, and that figure pushed American regulators to act. The Drug Enforcement Administration classified pregabalin as a depressant and placed it in Schedule V of the Controlled Substances Act. That schedule signals low abuse potential, though not none.

  Reports describe a calm, excited, "high" feeling comparable to cannabis. The two share depressant and appetite-stimulating effects, but cannabis is primarily anxiety-provoking with mild psychedelic effects. Pregabalin is an anxiety-reducing agent with mild euphoria that is prone to rapid tolerance.

  In Norway, the drug sits in prescription Schedule B, alongside benzodiazepines. In the United Kingdom, the Advisory Council on the Misuse of Drugs recommended on the 14th of January 2016 that pregabalin and gabapentin be controlled under the Misuse of Drugs Act 1971.

  In October 2018, the government announced that pregabalin would become a Class C controlled substance from April 2019. A prescription must now state the dose clearly.

  Australia has treated it as prescription-only Schedule 4 since its registration in 2005. Concerns grew anyway. National Coronial Information System data showed pregabalin-related deaths rising from 16 in 2013 to 121 in 2016. A 2019 study in the Medical Journal of Australia found a tenfold rise in related ambulance attendances in Victoria from 2012 to 2017.

  In 2021, the Therapeutic Goods Administration added boxed warnings about abuse and dependence. Every state and territory now monitors prescriptions in real time.

  Approved uses differ by country. The American FDA covers add-on therapy for partial-onset seizures, postherpetic neuralgia, nerve pain from spinal cord injury and diabetes, and fibromyalgia. Australia approves it for adult nerve pain and epilepsy, but not for anxiety or fibromyalgia. The European Union, the United Kingdom and Russia approve it for generalized anxiety disorder.

  Safety in pregnancy remains unclear, with some studies suggesting potential harm.

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• 8. Marketing, Patents and Price

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  Between 2008 and 2018, Pfizer ran extensive consumer advertising for Lyrica, aimed at fibromyalgia and diabetic nerve pain. Global revenues reached $14 billion, more than half from the United States.

  The company also promoted the drug for uses that regulators had not approved, through 2009. Pfizer pleaded guilty to charges tied to advertising and branding with the intent to defraud or mislead. For Lyrica and three other drugs, the Department of Justice fined it a record $2.3 billion.

  Prosecutor Michael Loucks described the scheme. Doctors were invited to consultant meetings, many in resort locations. Their expenses were paid, and they received a fee just for attending.

  The patent story ran on separate tracks. Northwestern University holds the pregabalin patent, exclusively licensed to Pfizer. Generic manufacturers challenged it and others, but the patent was upheld in 2014, which gave Pfizer exclusivity for Lyrica in the United States until 2018.

  In the United Kingdom, the main seizure patent expired in 2013. In November 2018, the UK Supreme Court ruled Pfizer's second patent, for pain, invalid for lack of evidence covering central and peripheral neuropathic pain.

  The delay carried a bill. From October 2015, GPs were forced to move patients from generic pregabalin to the branded version until the second patent ran out in July 2017. That cost the NHS £502 million.

  Generic competition arrived in the United States in July 2019, when a 150 mg capsule wholesaled for US$0.17-0.22. In 2023, it was the 78th most commonly prescribed medication in the country, with more than 8 million prescriptions.

  As of October 2017, the drug was sold under well over a hundred names worldwide, from Algerika and Lyrolin to Xablin. Another group of brands pairs it with mecobalamin. In the United States, Lyrica is now marketed by Viatris, after Upjohn was spun off from Pfizer.

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