Vigabatrin Explained

Watchedfields:changed
Verifiedrevid:470630102
Pronounce:
Tradename:Sabril, Vigpoder, Vigafyde
Pregnancy Au:D
Routes Of Administration:By mouth
Atc Prefix:N03
Atc Suffix:AG04
Legal Au:S4
Legal Br:C1
Legal Br Comment:[1]
Legal Ca:Rx-only
Legal Uk:POM
Legal Us:Rx-only
Legal Eu:Rx-only
Bioavailability:80–90%
Protein Bound:0%
Metabolism:not metabolized
Elimination Half-Life:5–8 hours in young adults, 12–13 hours in the elderly.
Excretion:Kidney
Iuphar Ligand:4821
Cas Number:68506-86-5
Pubchem:5665
Drugbank:DB01080
Chemspiderid:5463
Unii:GR120KRT6K
Kegg:D00535
Chembl:89598
Synonyms:γ-Vinyl-GABA
Iupac Name:(RS)-4-aminohex-5-enoic acid
C:6
H:11
N:1
O:2
Smiles:O=C(O)CCC(\C=C)N
Stdinchi:1S/C6H11NO2/c1-2-5(7)3-4-6(8)9/h2,5H,1,3-4,7H2,(H,8,9)
Stdinchikey:PJDFLNIOAUIZSL-UHFFFAOYSA-N
Melting Point:171
Melting High:177

Vigabatrin, sold under the brand names Vigafyde, Vigpoder and Sabril among others, is a medication used in the management and treatment of infantile spasms and refractory complex partial seizures.

It works by inhibiting the breakdown of γ-aminobutyric acid (GABA). It is also known as γ-vinyl-GABA, and is a structural analogue of GABA, but does not bind to GABA receptors.[2]

Vigabatrin is generally used only in cases of treatment-resistant epilepsy due to the risk of permanent vision loss.[3] Although estimates of visual field loss vary substantially, risk appears to be lower among infants with treatment duration less than 12 months and the risk of clinically meaningful vision loss is very low among children treated for infantile spasms.[4] [5]

Medical uses

Epilepsy

In Canada, vigabatrin is approved for use as an adjunctive treatment (with other drugs) in treatment resistant epilepsy, complex partial seizures, secondary generalized seizures, and for monotherapy use in infantile spasms in West syndrome.[2]

As of 2003, vigabatrin is approved in Mexico for the treatment of epilepsy that is not satisfactorily controlled by conventional therapy (adjunctive or monotherapy) or in recently diagnosed patients who have not tried other agents (monotherapy).[6]

Vigabatrin is also indicated for monotherapy use in secondarily generalized tonic-clonic seizures, partial seizures, and in infantile spasms due to West syndrome.[6]

In August 2009, Lundbeck announced that the US Food and Drug Administration had granted two New Drug Application approvals for vigabatrin. The drug is indicated as monotherapy for pediatric patients one month to two years of age with infantile spasms for whom the potential benefits outweigh the potential risk of permanent vision loss, and as adjunctive (add-on) therapy for adult patients with refractory complex partial seizures (CPS) who have inadequately responded to several alternative treatments and for whom the potential benefits outweigh the risk of vision loss.[7]

In 1994, Feucht and Brantner-Inthaler reported that vigabatrin reduced seizures by 50-100% in 85% of children with Lennox-Gastaut syndrome who had poor results with sodium valproate.[8]

Others

Vigabatrin reduced cholecystokinin tetrapeptide-induced symptoms of panic disorder, in addition to elevated cortisol and ACTH levels, in healthy volunteers.[9]

Vigabatrin is also used to treat seizures in succinic semialdehyde dehydrogenase deficiency (SSADHD), which is an inborn GABA metabolism defect that causes intellectual disability, hypotonia, seizures, speech disturbance, and ataxia through the accumulation of γ-Hydroxybutyric acid (GHB). Vigabatrin helps lower GHB levels through GABA transaminase inhibition. However, this is in the brain only; it has no effect on peripheral GABA transaminase, so the GHB keeps building up and eventually reaches the brain.[10]

Adverse effects

Central nervous system

Sleepiness (12.5%), headache (3.8%), dizziness (3.8%), nervousness (2.7%), depression (2.5%), memory disturbances (2.3%), diplopia (2.2%), aggression (2.0%), ataxia (1.9%), vertigo (1.9%), hyperactivity (1.8%), vision loss (1.6%) (See below), confusion (1.4%), insomnia (1.3%), impaired concentration (1.2%), personality issues (1.1%). Out of 299 children, 33 (11%) became hyperactive.[2]

Some patients develop psychosis during the course of vigabatrin therapy,[11] which is more common in adults than in children.[12] This can happen even in patients with no prior history of psychosis.[13] Other rare CNS side effects include anxiety, emotional lability, irritability, tremor, abnormal gait, and speech disorder.[2]

Gastrointestinal

Abdominal pain (1.6%), constipation (1.4%), vomiting (1.4%), and nausea (1.4%). Dyspepsia and increased appetite occurred in less than 1% of subjects in clinical trials.[2]

Body as a whole

Fatigue (9.2%), weight gain (5.0%), asthenia (1.1%).[2]

Teratogenicity

A teratology study conducted in rabbits found that a dose of 150 mg/kg/day caused cleft palate in 2% of pups and a dose of 200 mg/kg/day caused it in 9%. This may be due to a decrease in methionine levels, according to a study published in March 2001.[14] In 2005, a study conducted at the University of Catania was published stating that rats whose mothers had consumed 250–1000 mg/kg/day had poorer performance in the water maze and open-field tasks, rats in the 750 mg group were underweight at birth and did not catch up to the control group, and rats in the 1000 mg group did not survive pregnancy.[15]

There is no controlled teratology data in humans to date.

Sensory

In 2003, vigabatrin was shown by Frisén and Malmgren to cause irreversible diffuse atrophy of the retinal nerve fiber layer in a retrospective study of 25 patients.[16] This has the most effect on the outer area (as opposed to the macular, or central area) of the retina.[17] Visual field defects had been reported as early as 1997 by Tom Eke and others, in the UK. Some authors, including Comaish et al. believe that visual field loss and electrophysiological changes may be demonstrable in up to 50% of Vigabatrin users.

The retinal toxicity of vigabatrin can be attributed to a taurine depletion.[18]

Due to safety issues, the Vigabatrin REMS Program is required by the FDA to ensure informed decisions before initiating and to ensure appropriate use of this drug.[19]

Interactions

A study published in 2002 found that vigabatrin causes a statistically significant increase in plasma clearance of carbamazepine.[20]

In 1984, Drs Rimmer and Richens at the University of Wales reported that administering vigabatrin with phenytoin lowered the serum phenytoin concentration in patients with treatment-resistant epilepsy.[21] Five years later, the same two scientists reported a fall in concentration of phenytoin of 23% within five weeks in a paper describing their failed attempt at elucidating the mechanism behind this interaction.[22]

Pharmacology

Vigabatrin is an irreversible mechanism-based inhibitor of gamma-aminobutyric acid aminotransferase (GABA-AT), the enzyme responsible for the catabolism of GABA. Inhibition of GABA-AT results in increased levels of GABA in the brain.[23] Vigabatrin is a racemic compound, and its [S]-enantiomer is pharmacologically active.[24] ,[25]

Pharmacokinetics

With most drugs, elimination half-life is a useful predictor of dosing schedules and the time needed to reach steady state concentrations. In the case of vigabatrin, however, it has been found that the half-life of biologic activity is far longer than the elimination half-life.[26]

For vigabatrin, there is no range of target concentrations because researchers found no difference between the serum concentration levels of responders and those of non-responders.[27] Instead, the duration of action is believed to be more a function of the GABA-T resynthesis rate; levels of GABA-T do not usually return to their normal state until six days after stopping the medication.

History

Vigabatrin was developed in the 1980s with the specific goal of increasing GABA concentrations in the brain in order to stop an epileptic seizure. To do this, the drug was designed to irreversibly inhibit the GABA transaminase, which degrades the GABA substrate. Although the drug was approved for treatment in the United Kingdom in 1989, the authorized use of Vigabatrin by US Food and Drug Administration was delayed twice in the United States before 2009. It was delayed in 1983 because animal trials produced intramyelinic edema, however, the effects were not apparent in human trials so the drug design continued. In 1997, the trials were temporarily suspended because it was linked to peripheral visual field defects in humans.[28]

On June 17, 2024, Pyros Pharmaceuticals, Inc. announced that the U.S. Food and Drug Administration (FDA) approved Vigafyde, the first and only ready-to-use vigabatrin oral solution.[29]

Society and culture

Brand Names

Vigabatrin is sold as Vigafyde, Vigpoder and Sabril in the United States.

Sabril was approved in the United States on August 21, 2009, and is marketed in the U.S. by Lundbeck Inc., which acquired Ovation Pharmaceuticals, the U.S. sponsor in March 2009.

Vigpoder was approved in the United States on June 24, 2022, and is marketed in the U.S. by Pyros Pharmaceuticals, Inc. Pyros is providing ongoing personalized support services to caregivers through Pyros Total Care for those prescribed Vigpoder.[30]

Vigafyde was approved in the United States on June 17, 2024, and is marketed in the U.S. by Pyros Pharmaceuticals, Inc. Compared with other vigabatrin products, Vigafyde is a concentrated solution containing 100mg/mL of vigabatrin and requires a smaller volume than other vigabatrin products to obtain the same dosage (eg, currently available vigabatrin for oral solution products have a final concentration of 50mg/mL).[31]

Vigabatrin is sold as Sabril in Canada,[32] Mexico,and the United Kingdom.[33] The brand name in Denmark is Sabrilex.

Generic equivalents

In April 2017, the Food and Drug Administration approved the first generic powder packets for oral solution version of Sabril (vigabatrin) in the United States.[34] On January 16, 2019, the Food and Drug Administration approved the first generic tablet version of Sabril (vigabatrin) in the United States.[35]

Research

The PREVeNT Trial

The PREVeNT study found that early vigabatrin treatment delayed the onset and reduced the overall prevalence of infantile spasms in TSC infants. However, the seizure prevention was not seen for other seizure types, including focal seizures, that are highly prevalent in this population. PREVeNT, similarly to EPISTOP, reported a reduced incidence of infantile spasms up to 24 months of age.

EPISTOP Trial

Infantile spasms are seen in 50 to 70% of children with TSC, and are associated with both drug-resistance and intellectual disability. Importantly, in EPISTOP, none of the children who received preventive treatment developed infantile spasms throughout the 2-year course of the study, in contrast to 10 of 25 (40%) receiving conventional treatment.

Notes and References

  1. Web site: Anvisa . Brazilian Health Regulatory Agency . March 31, 2023 . RDC Nº 784 - Listas de Substâncias Entorpecentes, Psicotrópicas, Precursoras e Outras sob Controle Especial . Collegiate Board Resolution No. 784 - Lists of Narcotic, Psychotropic, Precursor, and Other Substances under Special Control. live . https://web.archive.org/web/20230803143925/https://www.in.gov.br/en/web/dou/-/resolucao-rdc-n-784-de-31-de-marco-de-2023-474904992 . August 3, 2023 . August 16, 2023 . . pt-BR . April 4, 2023.
  2. Web site: Long PW . Vigabatrin . Drug Monograph . https://web.archive.org/web/20060423082047/http://www.mentalhealth.com/drug/p30-s07.html . April 23, 2006 . Internet Mental Health . 2003 .
  3. Web site: Sabril (vigabatrin) Tablets for Oral Use, Powder for Oral Solution. Full Prescribing Information. Lundbeck.
  4. High vigabatrin dosage is associated with lower risk of infantile spasms relapse among children with tuberous sclerosis complex. 2018 . 6347124 . Hussain SA, Schmid E, Peters JM, Goyal M, Bebin EM, Northrup H, Sahin M, Krueger DA, Wu JY, Williams ME, Hanson E, Bing N, Kent B, o'Kelley S, Filip-Dhima R, Dies K, Bruns S, Scherrer B, Cutter G, Murray DS, Roberds SL . Tuberous Sclerosis Complex Autism Center of Excellence Network . Epilepsy Research . 148 . 1–7 . 10.1016/j.eplepsyres.2018.09.016 . 30296632 .
  5. A lack of clinically apparent vision loss among patients treated with vigabatrin with infantile spasms: The UCLA experience. 2016 . 26921595 . Schwarz MD, Li M, Tsao J, Zhou R, Wu YW, Sankar R, Wu JY, Hussain SA . Epilepsy & Behavior . 57 . Pt A . 29–33 . 10.1016/j.yebeh.2016.01.012 .
  6. Web site: DEF Mexico: Sabril . https://web.archive.org/web/20050914050706/http://www.facmed.unam.mx/bmnd/plm/mex/productos/10130.htm . September 14, 2005 . Diccionario de Especialdades Farmaceuticas. . 49 . 2003 .
  7. Bresnahan R, Gianatsi M, Maguire MJ, Tudur Smith C, Marson AG . Vigabatrin add-on therapy for drug-resistant focal epilepsy . The Cochrane Database of Systematic Reviews . 2020 . 7 . CD007302 . July 2020 . 32730657 . 8211760 . 10.1002/14651858.CD007302.pub3 .
  8. Feucht M, Brantner-Inthaler S . Gamma-vinyl-GABA (vigabatrin) in the therapy of Lennox-Gastaut syndrome: an open study . Epilepsia . 35 . 5 . 1994 . 993 - 8 . 7925171 . 10.1111/j.1528-1157.1994.tb02544.x. 24204172 .
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  15. Lombardo SA, Leanza G, Meli C, Lombardo ME, Mazzone L, Vincenti I, Cioni M . Maternal exposure to the antiepileptic drug vigabatrin affects postnatal development in the rat . Neurological Sciences . 26 . 2 . 2005 . 89 - 94 . 15995825 . 10.1007/s10072-005-0441-6 . 2108/194069 . 25257244 . free . September 3, 2019 . August 27, 2021 . https://web.archive.org/web/20210827182311/https://art.torvergata.it/retrieve/handle/2108/194069/383064/lombardo2005.pdf . live .
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  17. Buncic JR, Westall CA, Panton CM, Munn JR, MacKeen LD, Logan WJ . Characteristic retinal atrophy with secondary "inverse" optic atrophy identifies vigabatrin toxicity in children . Ophthalmology . 111 . 10 . 2004 . 1935 - 42 . 15465561 . 3880364 . 10.1016/j.ophtha.2004.03.036.
  18. Gaucher D, Arnault E, Husson Z, Froger N, Dubus E, Gondouin P, Dherbécourt D, Degardin J, Simonutti M, Fouquet S, Benahmed MA, Elbayed K, Namer IJ, Massin P, Sahel JA, Picaud S . Taurine deficiency damages retinal neurones: cone photoreceptors and retinal ganglion cells . Amino Acids . 43 . 5 . 1979–1993 . November 2012 . 22476345 . 3472058 . 10.1007/s00726-012-1273-3 .
  19. Web site: Sabril (vigabatrin) tablets, for oral use Sabril (vigabatrin) powder for oral.... Sabril.net. en. May 31, 2019.
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  28. Ben-Menachem E . Mechanism of action of vigabatrin: correcting misperceptions . Acta Neurologica Scandinavica. Supplementum . 124 . 192 . 5–15 . 2011 . 22061176 . 10.1111/j.1600-0404.2011.01596.x . 25347559 . free .
  29. Web site: June 17, 2024 . Pyros Pharmaceuticals Announces FDA Approval of VIGAFYDE™ (vigabatrin) as the First and Only Ready-to-Use Vigabatrin Oral Solution . June 18, 2024 . Businesswire.
  30. Web site: Pyros Total Care .
  31. Web site: PharmD . Brian Park . June 18, 2024 . Ready-to-Use Vigabatrin Oral Solution Approved for Infantile Spasms . June 18, 2024 . MPR . en-US.
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  34. Web site: Sabril (vigabatrin) – First-time generic . OptumRx.
  35. Kotulska K, Kwiatkowski DJ, Curatolo P, Weschke B, Riney K, Jansen F, Feucht M, Krsek P, Nabbout R, Jansen AC, Wojdan K, Sijko K, Głowacka-Walas J, Borkowska J, Sadowski K, Domańska-Pakieła D, Moavero R, Hertzberg C, Hulshof H, Scholl T, Benova B, Aronica E, de Ridder J, Lagae L, Jóźwiak S . Prevention of Epilepsy in Infants with Tuberous Sclerosis Complex in the EPISTOP Trial . Annals of Neurology . 89 . 2 . 304–314 . February 2021 . 33180985 . 7898885 . 10.1002/ana.25956 .