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Bogan RK, Bornemann MAC, Kushida CA, Trân PV, Barrett RW. Long-term maintenance treatment of restless legs syndrome with gabapentin enacarbil: a randomized controlled study. Mayo Clin Proc 2010; 85:512-21. [PMID: 20511481 PMCID: PMC2878254 DOI: 10.4065/mcp.2009.0700] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
OBJECTIVE To assess maintenance of efficacy and tolerability of gabapentin enacarbil in patients with moderate to severe primary restless legs syndrome (RLS). PATIENTS AND METHODS This study (conducted April 18, 2006, to November 14, 2007) comprised a 24-week, single-blind (SB) treatment phase (gabapentin enacarbil, 1200 mg) followed by a 12-week randomized, double-blind (DB) phase. Responders from the SB phase (patients with improvements on the International Restless Legs Scale [IRLS] and investigator-rated Clinical Global Impression-Improvement scale at week 24 and stable while taking a gabapentin enacarbil dose of 1200 mg for at least 1 month before randomization) were randomized to gabapentin enacarbil, 1200 mg, or placebo once daily at 5 pm with food. The primary end point was the proportion of patients experiencing relapse (worse scores on the IRLS and investigator-rated Clinical Global Impression of Change scale on 2 consecutive visits at least 1 week apart or withdrawal because of lack of efficacy) during the DB phase. RESULTS A total of 221 of 327 patients completed the SB phase, 194 (96 in the gabapentin enacarbil group and 98 in the placebo group) were randomized to DB treatment, and 168 (84 in the gabapentin enacarbil group and 84 in the placebo group) completed the DB phase. A significantly smaller proportion of patients treated with gabapentin enacarbil (9/96 [9%]) experienced relapse compared with the placebo-treated patients (22/97 [23%]) (odds ratio, 0.353; 95% confidence interval, 0.2-0.8; P=.02). Somnolence and dizziness were the most common adverse events. One death occurred (unintentional choking during the SB phase) and was judged as being unrelated to the study drug. No clinically relevant changes were observed in laboratory values, in vital signs, or on electrocardiograms. CONCLUSION Gabapentin enacarbil, 1200 mg, maintained improvements in RLS symptoms compared with placebo and showed long-term tolerability in adults with moderate to severe primary RLS for up to 9 months of treatment.
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Agarwal P, Griffith A, Costantino HR, Vaish N. Gabapentin enacarbil - clinical efficacy in restless legs syndrome. Neuropsychiatr Dis Treat 2010; 6:151-8. [PMID: 20505847 PMCID: PMC2874339 DOI: 10.2147/ndt.s5712] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Restless legs syndrome (RLS) is a sleep-related movement disorder commonly involving an unpleasant urge to move the limbs, typically the legs. Dopaminergic agents represent the first-line therapy for RLS; however, long-term use of such drugs results in worsening symptoms due to "augmentation" or other adverse events. Gabapentin, an analog of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), is an anticonvulsant/analgesic agent. Gabapentin is only mildly effective in relieving RLS symptoms, perhaps a result of its poor absorption from the gastrointestinal (GI) tract. Gabapentin enacarbil is a prodrug of gabapentin specifically designed to enhance absorption via the GI tract, and hence provide improved circulating levels of gabapentin on metabolism. Clinical trials to date have demonstrated favorable safety and (compared to traditional gabapentin) improved pharmacokinetics and efficacy in treating RLS symptoms. Thus, gabapentin enacarbil may prove to be a useful drug in treating RLS. An application of gabapentin enacarbil for treatment of RLS is currently pending with FDA for approval.
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103
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Gabapentin enacarbil in restless legs syndrome: a phase 2b, 2-week, randomized, double-blind, placebo-controlled trial. Clin Neuropharmacol 2010; 32:311-20. [PMID: 19667976 DOI: 10.1097/wnf.0b013e3181b3ab16] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES Assess the efficacy and tolerability of gabapentin enacarbil (GEn), a transported prodrug of gabapentin with improved gabapentin exposure, in adults with moderate-to-severe primary restless legs syndrome. METHODS This 14-day, double-blind, randomized, controlled trial of GEn at 1200 or 600 mg or placebo taken once daily, evaluated the mean change from baseline International Restless Legs Scale (IRLS) total score at end of treatment (day 14:primary comparison, GEn at 1200 mg vs placebo). Secondary end points included Clinical Global Impression-Improvement scale outcomes at day 14. RESULTS Ninety-five subjects were randomized (GEn: 1200 mg, n = 33 and 600 mg, n = 29; placebo, n = 33); 2 subjects (GEn at 1200 mg) withdrew because of adverse events. At day 14,the mean (SD) change from baseline IRLS total score was significantly greater with GEn at 1200 mg (-16.1 [7.93]) compared with placebo (-8.9 [7.72]; adjusted mean treatment difference, -7.2; P < 0.0001). Investigator-rated Clinical Global Impression-Improvement scale responses also significantly favored GEn at 1200 mg compared with placebo (P G 0.0001).The mean (SD) change from baseline IRLS total score with GEn at 600 mg at day 14 was -9.1 (5.95), similar to placebo. The most commonly reported treatment-emergent adverse events were somnolence (GEn: 1200 mg, 36% and 600 mg, 14%; placebo,15%) and dizziness (GEn: 1200 mg, 18% and 600 mg, 14%; placebo, 3%), most of which were rated mild or moderate in intensity. CONCLUSIONS Gabapentin enacarbil at 1200 mg significantly improved restless legs syndrome symptoms compared with placebo. Efficacy outcomes for GEn at 600 mg were similar to placebo. Both GEn doses were generally well tolerated.
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Bialer M, White HS. Key factors in the discovery and development of new antiepileptic drugs. Nat Rev Drug Discov 2010; 9:68-82. [PMID: 20043029 DOI: 10.1038/nrd2997] [Citation(s) in RCA: 374] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Since the early 1990s, many new antiepileptic drugs (AEDs) that offer appreciable advantages in terms of their favourable pharmacokinetics, improved tolerability and lower potential for drug-drug interactions have entered the market. However, despite the therapeutic arsenal of old and new AEDs, approximately 30% of patients with epilepsy still suffer from seizures. Thus, there remains a substantial need for the development of more efficacious AEDs for patients with refractory seizures. Here, we briefly review the emerging knowledge on the pathological basis of epilepsy and how it might best be used in the design of new therapeutics. We also discuss the current approach to AED discovery and highlight some of the unique features of newer models of pharmacoresistance and epileptogenesis that have emerged in recent years.
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Affiliation(s)
- Meir Bialer
- Institute of Drug Research, School of Pharmacy, Faculty of Medicine, and the David R. Bloom Centre for Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel.
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105
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Jones R, Rickards H, Cavanna AE. Gabapentin Enacarbil: Pharmacotherapy of Restless Legs Syndrome. J Cent Nerv Syst Dis 2010; 2:45-55. [PMID: 23861631 PMCID: PMC3661230 DOI: 10.4137/jcnsd.s4886] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Restless Legs Syndrome (RLS) is a prevalent sleep-associated movement disorder greatly affecting patients’ quality of life (QoL). Several drugs can be used to control this condition although the first-line dopamine agents often cause adverse effects. Non-dopaminergic drugs such as oral gabapentin (GBP) have been more recently advocated. Despite ameliorating RLS symptoms, GBP’s pharmacokinetic limitations restrict its overall effectiveness. A novel specifically designed prodrug, gabapentin enacarbil (GE), has demonstrated successful RLS alleviation with a superior pharmacokinetic profile. This review aims to examine the efficacy and tolerability of both GBP and GE as pharmacotherapy for RLS. Despite some heterogeneity and limitations across research methodologies, GE appears to be a potential RLS therapy superior to GBP and other dopaminergic agents.
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Affiliation(s)
- Ruth Jones
- Department of Neuropsychiatry, BSMHFT and University of Birmingham, Birmingham, UK
| | - Hugh Rickards
- Department of Neuropsychiatry, BSMHFT and University of Birmingham, Birmingham, UK
| | - Andrea Eugenio Cavanna
- Department of Neuropsychiatry, BSMHFT and University of Birmingham, Birmingham, UK
- Department of Neurology, UHB and University of Birmingham, Birmingham, UK
- Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, UCL, London, UK
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Lal R, Sukbuntherng J, Luo W, Chen D, Vu A, Tovera J, Cundy KC. Pharmacokinetics and tolerability of single escalating doses of gabapentin enacarbil: a randomized-sequence, double-blind, placebo-controlled crossover study in healthy volunteers. Clin Ther 2009; 31:1776-86. [PMID: 19808136 DOI: 10.1016/j.clinthera.2009.07.026] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/23/2009] [Indexed: 11/25/2022]
Abstract
BACKGROUND Gabapentin enacarbil is an actively transported prodrug of gabapentin that provides predictable dose-proportional gabapentin exposure with high (> or =68%) oral bioavailability. OBJECTIVES The aims of this study were to investigate the pharmacokinetics and tolerability of gabapentin enacarbil up to supratherapeutic doses and the effects of gabapentin enacarbil on cardiac repolarization in healthy volunteers, and to provide a dose reference for a future definitive QT/corrected QT (QTc) study. METHODS This was a randomized-sequence, double-blind, placebo-controlled, single escalating-dose, crossover study of gabapentin enacarbil 600-mg extended-release tablets administered as a single oral dose of 2400, 3600, 4800, or 6000 mg or placebo, with a 1-week washout between administrations. Blood samples were collected over a period of 36 hours after administration and were analyzed using a validated method of liquid chromatography/tandem mass spec-trometry. Blood gabapentin enacarbil and gabapentin concentrations were analyzed using noncompartmental methods. Tolerability was assessed by monitoring adverse events (AEs) (using subject interview/reporting), laboratory parameters, vital sign measurements, and 12-lead electrocardiography (ECG). Holter ECG was also performed. RESULTS Thirty-two healthy volunteers were included in the study (18 women, 14 men; mean [SD] age, 31.2 [11.4] years; body mass index, 24.9 [3.04] kg/m(2)). Gabapentin enacarbil was converted rapidly to gaba-pentin after absorption. Gabapentin exposure in blood was proportional to gabapentin enacarbil dose over the range of 2400 to 6000 mg (1250-3125 mg-equivalent gabapentin). Blood concentrations of intact gabapen-tin enacarbil were low and transient (< or =0.5% of the released gabapentin concentration at all doses). The most commonly reported AEs were dizziness and nausea (50% and 25% of subjects, respectively). All but 4 AEs were mild to moderate in intensity. Two subjects experienced treatment-emergent AEs rated as severe: psychomotor retardation, vertigo, and sedation (4800-mg dose) and somnolence (6000 mg). All treatment-emergent AEs resolved without medical intervention. No serious AEs were reported, and none of the AEs led to study withdrawal. There were no clinically significant changes in laboratory parameters, vital sign measurements, or ECG values; QTc intervals did not exceed 480 msec or change from baseline >30 msec at any gabapentin enacarbil dose. CONCLUSIONS Gabapentin enacarbil was associated with dose-proportional gabapentin exposure at doses up to 6000 mg and was generally well tolerated in these healthy subjects. These findings support the use of 6000-mg gabapentin enacarbil in a definitive QT/QTc study.
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Affiliation(s)
- Ritu Lal
- XenoPort, Inc., Santa Clara, California 95051, USA.
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107
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Lal R, Sukbuntherng J, Tai EHL, Upadhyay S, Yao F, Warren MS, Luo W, Bu L, Nguyen S, Zamora J, Peng G, Dias T, Bao Y, Ludwikow M, Phan T, Scheuerman RA, Yan H, Gao M, Wu QQ, Annamalai T, Raillard SP, Koller K, Gallop MA, Cundy KC. Arbaclofen placarbil, a novel R-baclofen prodrug: improved absorption, distribution, metabolism, and elimination properties compared with R-baclofen. J Pharmacol Exp Ther 2009; 330:911-21. [PMID: 19502531 DOI: 10.1124/jpet.108.149773] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Baclofen is a racemic GABA(B) receptor agonist that has a number of significant pharmacokinetic limitations, including a narrow window of absorption in the upper small intestine and rapid clearance from the blood. Arbaclofen placarbil is a novel transported prodrug of the pharmacologically active R-isomer of baclofen designed to be absorbed throughout the intestine by both passive and active mechanisms via the monocarboxylate type 1 transporter. Arbaclofen placarbil is rapidly converted to R-baclofen in human and animal tissues in vitro. This conversion seems to be primarily catalyzed in human tissues by human carboxylesterase-2, a major carboxylesterase expressed at high levels in various tissues including human intestinal cells. Arbaclofen placarbil was efficiently absorbed and rapidly converted to R-baclofen after oral dosing in rats, dogs, and monkeys. Exposure to R-baclofen was proportional to arbaclofen placarbil dose, whereas exposure to intact prodrug was low. Arbaclofen placarbil demonstrated enhanced colonic absorption, i.e., 5-fold higher R-baclofen exposure in rats and 12-fold higher in monkeys compared with intracolonic administration of R-baclofen. Sustained release formulations of arbaclofen placarbil demonstrated sustained R-baclofen exposure in dogs with bioavailability up to 68%. In clinical use, arbaclofen placarbil may improve the treatment of patients with gastroesophageal reflux disease, spasticity, and numerous other conditions by prolonging exposure and decreasing the fluctuations in plasma levels of R-baclofen.
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Affiliation(s)
- Ritu Lal
- XenoPort, Inc., 3410 Central Expressway, Santa Clara, CA 95051, USA.
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108
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Bennewitz MF, Saltzman WM. Nanotechnology for delivery of drugs to the brain for epilepsy. Neurotherapeutics 2009; 6:323-36. [PMID: 19332327 PMCID: PMC2673491 DOI: 10.1016/j.nurt.2009.01.018] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2008] [Revised: 01/23/2009] [Accepted: 01/23/2009] [Indexed: 01/16/2023] Open
Abstract
Epilepsy results from aberrant electrical activity that can affect either a focal area or the entire brain. In treating epilepsy with drugs, the aim is to decrease seizure frequency and severity while minimizing toxicity to the brain and other tissues. Antiepileptic drugs (AEDs) are usually administered by oral and intravenous routes, but these drug treatments are not always effective. Drug access to the brain is severely limited by a number of biological factors, particularly the blood-brain barrier, which impedes the ability of AEDs to enter and remain in the brain. To improve the efficacy of AEDs, new drug delivery strategies are being developed; these methods fall into the three main categories: drug modification, blood-brain barrier modification, and direct drug delivery. Recently, all three methods have been improved through the use of drug-loaded nanoparticles.
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Affiliation(s)
- Margaret F. Bennewitz
- grid.47100.320000000419368710Department of Biomedical Engineering, Yale University, 414 Malone Engineering Center, 55 Prospect Street, 06520-8260 New Haven, CT
| | - W. Mark Saltzman
- grid.47100.320000000419368710Department of Biomedical Engineering, Yale University, 414 Malone Engineering Center, 55 Prospect Street, 06520-8260 New Haven, CT
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109
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Biopharmaceutical aspects of gastro-retentive dosage forms: the gabapentin paradigm. J Drug Deliv Sci Technol 2009. [DOI: 10.1016/s1773-2247(09)50046-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Cundy KC, Sastry S, Luo W, Zou J, Moors TL, Canafax DM. Clinical pharmacokinetics of XP13512, a novel transported prodrug of gabapentin. J Clin Pharmacol 2008; 48:1378-88. [PMID: 18827074 DOI: 10.1177/0091270008322909] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Gabapentin absorption occurs in only a limited region of the small intestine and saturates at doses used clinically, resulting in dose-dependent pharmacokinetics, high interpatient variability, and potentially ineffective drug exposure. XP13512/GSK1838262 is a novel transported prodrug of gabapentin that is absorbed throughout the entire length of the intestine by high-capacity nutrient transporters. In 4 studies of healthy volunteers (136 subjects total), the pharmacokinetics of XP13512 immediate- and extended-release formulations were compared with those of oral gabapentin. XP13512 immediate-release (up to 2800 mg single dose and 2100 mg twice daily) was well absorbed (>68%, based on urinary recovery of gabapentin), converted rapidly to gabapentin, and provided dose-proportional exposure, whereas absorption of oral gabapentin declined with increasing doses to <27% at 1200 mg. Compared with 600 mg gabapentin, an equimolar XP13512 extended-release dose provided extended gabapentin exposure (time to maximum concentration, 8.4 vs 2.7 hours) and superior bioavailability (74.5% vs 36.6%). XP13512 may therefore provide more predictable gabapentin exposure and decreased dosing frequency.
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Affiliation(s)
- Kenneth C Cundy
- XenoPort Inc, 3410 Central Expressway, Santa Clara, CA 95051, USA.
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111
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Rhee YS, Park S, Lee TW, Park CW, Nam TY, Oh TO, Jeon JW, Han SB, Lee DS, Park ES. In Vitro/in Vivo relationship of gabapentin from a sustained-release tablet formulation: A pharmacokinetic study in the beagle dog. Arch Pharm Res 2008; 31:911-7. [DOI: 10.1007/s12272-001-1246-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 03/20/2008] [Accepted: 07/03/2008] [Indexed: 10/21/2022]
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112
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Morris ME, Felmlee MA. Overview of the proton-coupled MCT (SLC16A) family of transporters: characterization, function and role in the transport of the drug of abuse gamma-hydroxybutyric acid. AAPS JOURNAL 2008; 10:311-21. [PMID: 18523892 DOI: 10.1208/s12248-008-9035-6] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Accepted: 04/01/2008] [Indexed: 11/30/2022]
Abstract
The transport of monocarboxylates, such as lactate and pyruvate, is mediated by the SLC16A family of proton-linked membrane transport proteins known as monocarboxylate transporters (MCTs). Fourteen MCT-related genes have been identified in mammals and of these seven MCTs have been functionally characterized. Despite their sequence homology, only MCT1-4 have been demonstrated to be proton-dependent transporters of monocarboxylic acids. MCT6, MCT8 and MCT10 have been demonstrated to transport diuretics, thyroid hormones and aromatic amino acids, respectively. MCT1-4 vary in their regulation, tissue distribution and substrate/inhibitor specificity with MCT1 being the most extensively characterized isoform. Emerging evidence suggests that in addition to endogenous substrates, MCTs are involved in the transport of pharmaceutical agents, including gamma-hydroxybuytrate (GHB), 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins), salicylic acid, and bumetanide. MCTs are expressed in a wide range of tissues including the liver, intestine, kidney and brain, and as such they have the potential to impact a number of processes contributing to the disposition of xenobiotic substrates. GHB has been extensively studied as a pharmaceutical substrate of MCTs; the renal clearance of GHB is dose-dependent with saturation of MCT-mediated reabsorption at high doses. Concomitant administration of GHB and L: -lactate to rats results in an approximately two-fold increase in GHB renal clearance suggesting that inhibition of MCT1-mediated reabsorption of GHB may be an effective strategy for increasing renal and total GHB elimination in overdose situations. Further studies are required to more clearly define the role of MCTs on drug disposition and the potential for MCT-mediated detoxification strategies in GHB overdose.
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Affiliation(s)
- Marilyn E Morris
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, State University of New York, Amherst, New York 14260, USA.
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113
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Abstract
Prodrugs are bioreversible derivatives of drug molecules that undergo an enzymatic and/or chemical transformation in vivo to release the active parent drug, which can then exert the desired pharmacological effect. In both drug discovery and development, prodrugs have become an established tool for improving physicochemical, biopharmaceutical or pharmacokinetic properties of pharmacologically active agents. About 5-7% of drugs approved worldwide can be classified as prodrugs, and the implementation of a prodrug approach in the early stages of drug discovery is a growing trend. To illustrate the applicability of the prodrug strategy, this article describes the most common functional groups that are amenable to prodrug design, and highlights examples of prodrugs that are either launched or are undergoing human trials.
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114
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Simplício AL, Clancy JM, Gilmer JF. Prodrugs for amines. Molecules 2008; 13:519-47. [PMID: 18463563 PMCID: PMC6245426 DOI: 10.3390/molecules13030519] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 02/25/2008] [Accepted: 02/25/2008] [Indexed: 11/21/2022] Open
Abstract
The purpose of this work is to review the published strategies for the production of prodrugs of amines. The review is divided in two main groups of approaches: those that rely on enzymatic activation and those that take advantage of physiological chemical conditions for release of the drugs. A compilation of the most important approaches is presented in the form of a table, where the main advantages and disadvantages of each strategy are also referred.
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Affiliation(s)
- Ana L. Simplício
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República – EAN, 2780-157 Oeiras, Portugal
- IBET, Apartado 12, 2781-901 Oeiras, Portugal
- Author to whom correspondence should be addressed; E-mail:
| | - John M. Clancy
- School of Pharmacy, Trinity College, Dublin 2, Ireland; E-mails: ;
| | - John F. Gilmer
- School of Pharmacy, Trinity College, Dublin 2, Ireland; E-mails: ;
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115
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Rautio J, Laine K, Gynther M, Savolainen J. Prodrug approaches for CNS delivery. AAPS JOURNAL 2008; 10:92-102. [PMID: 18446509 DOI: 10.1208/s12248-008-9009-8] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Accepted: 01/04/2008] [Indexed: 12/29/2022]
Abstract
Central nervous system (CNS) drug delivery remains a major challenge, despite extensive efforts that have been made to develop novel strategies to overcome obstacles. Prodrugs are bioreversible derivatives of drug molecules that must undergo an enzymatic and/or chemical transformation in vivo to release the active parent drug, which subsequently exerts the desired pharmacological effect. In both drug discovery and drug development, prodrugs have become an established tool for improving physicochemical, biopharmaceutical or pharmacokinetic properties of pharmacologically active agents that overcome barriers to a drug's usefulness. This review provides insight into various prodrug strategies explored to date for CNS drug delivery, including lipophilic prodrugs, carrier- and receptor-mediated prodrug delivery systems, and gene-directed enzyme prodrug therapy.
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Affiliation(s)
- Jarkko Rautio
- Department of Pharmaceutical Chemistry, University of Kuopio, PO Box 1627, FI-70211, Kuopio, Finland.
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116
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Gynther M, Laine K, Ropponen J, Leppänen J, Mannila A, Nevalainen T, Savolainen J, Järvinen T, Rautio J. Large Neutral Amino Acid Transporter Enables Brain Drug Delivery via Prodrugs. J Med Chem 2008; 51:932-6. [DOI: 10.1021/jm701175d] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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117
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Bialer M, Johannessen SI, Kupferberg HJ, Levy RH, Perucca E, Tomson T. Progress report on new antiepileptic drugs: a summary of the Eigth Eilat Conference (EILAT VIII). Epilepsy Res 2006; 73:1-52. [PMID: 17158031 DOI: 10.1016/j.eplepsyres.2006.10.008] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2006] [Accepted: 10/30/2006] [Indexed: 12/15/2022]
Abstract
The Eigth Eilat Conference on New Antiepileptic Drugs (AEDs)-EILAT VII, took place in Sitges, Barcelona from the 10th to 14th September, 2006. Basic scientists, clinical pharmacologists and neurologists from 24 countries attended the conference, whose main themes included a focus on status epilepticus (epidemiology, current and future treatments), evidence-based treatment guidelines and the potential of neurostimulation in refractory epilepsy. Consistent with previous formats of this conference, the central part of the conference was devoted to a review of AEDs in development, as well as updates on marketed AEDs introduced since 1989. This article summarizes the information presented on drugs in development, including brivaracetam, eslicarbazepine acetate (BIA-2-093), fluorofelbamate, ganaxolone, huperzine, lacosamide, retigabine, rufinamide, seletracetam, stiripentol, talampanel, valrocemide, JZP-4, NS1209, PID and RWJ-333369. Updates on felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine and new extended release oxcarbazepine formulations, pregabalin, tiagabine, topiramate, vigabatrin, zonisamide and new extended release valproic acid formulations, and the antiepileptic vagal stimulator device are also presented.
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Affiliation(s)
- Meir Bialer
- Department of Pharmaceutics, School of Pharmacy, David R. Bloom Center for Pharmacy, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel.
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Bialer M. New antiepileptic drugs that are second generation to existing antiepileptic drugs. Expert Opin Investig Drugs 2006; 15:637-47. [PMID: 16732716 DOI: 10.1517/13543784.15.6.637] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In the last decade, 10 new antiepileptic drugs (AEDs) have been introduced that offer appreciable advantages in terms of their favourable pharmacokinetics, improved tolerability and lower potential for drug interactions. However, despite the large therapeutic range of old and new AEDs, approximately 30% of the patients with epilepsy are still not seizure free and, consequently, there is a substantial need to develop new AEDs. The new AEDs currently in development can be divided into two categories: drugs with completely new chemical structures such as lacosamide (formally harkoseride), retigabine, rufinamide and talampanel; and drugs that are derivatives or analogues of existing AEDs that can be regarded as second-generation or follow-up compounds of established AEDs. This article focuses on the second category and thus critically reviews the following second-generation compounds: eslicarbazepine acetate or BIA-2-093 and 10-hydroxy carbazepine (carbamazepine derivatives); valrocemide and NPS 1776 (isovaleramide; valproic acid derivatives); pregabalin and XP13512 (gabapentin derivatives); brivaracetam (ucb 34714) and seletracetam (ucb 44212; levetiracetam derivatives); and fluorofelbamate (a felbamate derivative). In addition, a series of valproic acid derivatives that are currently in preclinical stage has also been evaluated because some lead compounds of this series have a promising potential to become new antiepileptics and CNS drugs. For any of these follow-up compounds to become a successful second generation to an existing AED, it has to be more potent, safer and possess favourable pharmacokinetics, including low potential for pharmacokinetic and pharmacodynamic drug interactions.
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Affiliation(s)
- Meir Bialer
- The Hebrew University of Jerusalem, Department of Pharmaceutics, School of Pharmacy, Faculty of Medicine, P.O. Box 12065, Ein Karem, Jerusalem 91120, Israel.
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Recent Advances in Oral Prodrug Discovery. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2006. [DOI: 10.1016/s0065-7743(06)41027-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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120
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Abstract
Efforts to improve oral drug bioavailability have grown in parallel with the pharmaceutical industry. As the number and chemical diversity of drugs has increased, new strategies have been required to develop orally active therapeutics. The past two decades have been characterised by an increased understanding of the causes of low bioavailability and a great deal of innovation in oral drug delivery technologies, marked by an unprecedented growth of the drug delivery industry. The advent of biotechnology and consequent proliferation of biopharmaceuticals have brought new challenges to the drug delivery field. In spite of the difficulties associated with developing oral forms of this type of therapeutics, significant progress has been made in the past few years, with some oral proteins, peptides and other macromolecules currently advancing through clinical trials. This article reviews the approaches that have been successfully applied to improve oral drug bioavailability, primarily, prodrug strategies, lead optimisation through medicinal chemistry and formulation design. Specific strategies to improve the oral bioavailability of biopharmaceuticals are also discussed.
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121
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Abstract
Drug development is a risky business, and the final product can have serious, sometimes deadly flaws. But by focusing on fixing those flaws, companies are catapulting themselves to profitability.
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Cundy KC, Annamalai T, Bu L, De Vera J, Estrela J, Luo W, Shirsat P, Torneros A, Yao F, Zou J, Barrett RW, Gallop MA. XP13512 [(+/-)-1-([(alpha-isobutanoyloxyethoxy)carbonyl] aminomethyl)-1-cyclohexane acetic acid], a novel gabapentin prodrug: II. Improved oral bioavailability, dose proportionality, and colonic absorption compared with gabapentin in rats and monkeys. J Pharmacol Exp Ther 2004; 311:324-33. [PMID: 15146029 DOI: 10.1124/jpet.104.067959] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The absorption of gabapentin (Neurontin) is dose-dependent and variable between patients. Rapid clearance of the drug necessitates dosing three or more times per day to maintain therapeutic levels. These deficiencies appear to result from the low capacity, limited intestinal distribution, and variable expression of the solute transporter responsible for gabapentin absorption. Saturation of this transporter at doses used clinically leads to unpredictable drug exposure and potentially ineffective therapy in some patients. XP13512 [(+/-)-1-([(alpha-isobutanoyloxyethoxy)carbonyl]aminomethyl)-1-cyclohexane acetic acid] is a novel prodrug of gabapentin designed to be absorbed by high-capacity nutrient transporters located throughout the intestine. XP13512 was efficiently absorbed and rapidly converted to gabapentin after oral dosing in rats and monkeys. Exposure to gabapentin was proportional to prodrug dose, whereas exposure to intact XP13512 was low. In rats, >95% of an oral dose of (14)C-XP13512 was excreted in urine in 24 h as gabapentin. In monkeys, oral bioavailability of gabapentin from XP13512 capsules was 84.2% compared with 25.4% after a similar oral Neurontin dose. Compared with intracolonic gabapentin, intracolonic XP13512 gave a 17-fold higher gabapentin exposure in rats and 34-fold higher in monkeys. XP13512 may therefore be incorporated into a sustained release formulation to provide extended gabapentin exposure. XP13512 demonstrated improved gabapentin bioavailability, increased dose proportionality, and enhanced colonic absorption. In clinical use, XP13512 may improve the treatment of neuropathic pain, epilepsy, and numerous other conditions by increasing efficacy, reducing interpatient variability, and decreasing frequency of dosing.
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Affiliation(s)
- Kenneth C Cundy
- XenoPort, Inc., 3410 Central Expressway, Santa Clara, CA 95051, USA.
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