Therapeutics

Rivastigmine

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Overview

Name: Rivastigmine
Synonyms: Exelon™, Rivastigmine tartrate , Rivastach® Patch, Prometax®, SDZ ENA 713
Chemical Name: (S)-3-[1-(dimethylamino)ethyl]phenyl N-ethyl-N-methylcarbamate
Therapy Type: Small Molecule
Target Type: Cholinergic System
Condition(s): Alzheimer's Disease, Parkinson's Disease Dementia
U.S. FDA Status: Alzheimer's Disease (Approved), Parkinson's Disease Dementia (Approved)
Company: Novartis Pharmaceuticals Corporation
Approved for: Mild to moderate Alzheimer’s disease and mild to moderate dementia related to Parkinson's disease

Background

Rivastigmine is a reversible inhibitor of both the acetylcholinesterase and butyrylcholinesterase enzymes. It is widely used for the treatment of Alzheimer's across its mild, moderate, and severe stages, as well as for the treatment of dementia associated with Parkinson's disease (PDD). Rivastigmine was first approved to be marketed for AD in 1997 in Switzerland, and in the years since has come to be available in some 80 countries worldwide, including the United States, Canada, and Europe, for both AD and PDD.

This drug was originally formulated as a twice-daily oral capsule, and it was the first AD therapy to be made available as a skin patch that provides continuous delivery of the drug over 24 hours. The patch is sold in three doses, though not all are available in all countries. By way of transdermal absorption, the patch provides steady plasma concentrations of rivastigmine and bypasses first-pass metabolism in the intestine and liver. Because it generates markedly fewer gastrointestinal side effects, it enables patients to receive a higher therapeutic dose (Cummings et al., 2007). Generic versions of different doses of rivastigmine capsules started becoming available in 2010. A generic version of the rivastigmine transdermal patch is on hold pending resolution of a patent dispute (Law360 story).

Rivastigmine's side effects are consistent with class effects of cholinesterase inhibition. They include most commonly nausea, vomiting, diarrhea, and loss of appetite, and less frequently agitation, depression, dizziness, fatigue/sleeplessness, and others. Side effects tend to be strongest in the beginning weeks, when the dose is titrated up to the therapeutic level, and milder in the maintenance phase. Apart from rare skin sensitivity reactions, the patch is generally better tolerated than the capsules.

Findings

About 65 clinical trials Phase 2 and higher have been registered with rivastigmine. For example, in a six-month North American trial comparing a dose of 6-12 mg/day to 1-4 mg/day and to placebo in 699 patients with mild to moderate AD, rivastigmine capsules showed a modest but dose-dependent treatment benefit on cognition, function, and activities of daily living as measured by the ADAS-cog, the CIBIC-plus, and the Progressive Deterioration Scale (PDS), respectively. A similar European trial in 725 patients with mild to moderate AD that compared 6-12 mg/day to 1-4 mg/day of rivastigmine and placebo, also for six months and using the same outcome measures, had similar results. Only a quarter to a third of patients had a significant treatment response to rivastigmine capsules (Corey-Bloom et al., 1998; Rosler et al., 1999).

The skin patch formulation was evaluated in the six-month, Phase 3 IDEAL (Investigation of transDermal Exelon in ALzheimer's disease) study in 1,195 patients with mild to moderate AD. Participants received either one of two doses of the rivastigmine patch (9.5 or 17.4 mg over the course of 24 hours), 6-mg twice-daily capsules, or placebo. On efficacy, both doses of the patch outperformed placebo; the lower-dose patch with a similar effect to that of the capsules, the high-dose patch adding a small benefit on cognition. With the patch, the incidence of gastrointestinal complaints dropped nearly to that of placebo, and two-thirds of caregivers said they preferred the patch. More recently, a six-month, 716-patient trial comparing a 4.6 mg/24-hour to a 13.3 mg/24-hour patch reported that the higher dose was more efficacious at comparable tolerability (e.g., Grossberg et al., 2007Grossberg et al., 2011Farlow et al., 2013). An open-label study in a real-life clinical setting outside of randomized controlled trials reported that 969 patients with mild to moderate AD treated with the rivastigmine patch tended to maintain cognitive and global function over 18 months (Gauthier et al., 2013).

Most double-blind randomized controlled trials of rivastigmine lasted three to six months; however, some longer-term treatment data are available from open-label extensions or from analyses of clinical observation. For example, one study of 1,998 patients treated for up to five years found that their mean baseline MMSE score of 19.3 declined to above 10 points after five years of rivastigmine treatment, while model-based projections predicted that without treatment it would have declined to below 10 points by three years. Other studies reported clinically meaningful treatment benefits compared with historical controls for two years of treatment (Small et al., 2005Grossberg et al., 2004).

Overall, the acetylcholinesterase therapies donepezil, rivastigmine, and galantamine are viewed as having similar efficacy and safety, but direct side-by-side comparisons are few. One three-month study randomized 111 patients with mild to moderate AD to either donepezil titrated up to 10 mg once daily, or rivastigmine capsules up to 6 mg twice daily. Both regimens led to comparable symptomatic benefits on cognition. Donepezil was better tolerated, though this has since changed with the rivastigmine patch (Wilkinson et al., 2001). A two-year trial comparing rivastigmine to donepezil in 994 patients with moderate to severe AD found that almost half dropped out, most due to gastrointestinal side effects. Patients who continued had a similar benefit with either therapy on measures of cognition and behavior, though rivastigmine appeared to perform slightly better on activities of daily living and global function. Subgroup analyses hinted at better results for rivastigmine in patients with a particular butyrylcholinesterase genotype and patients who had symptoms of concomitant Lewy body disease, as well (Bullock et al, 2005).

Several trials have evaluated rivastigmine for dementia with Lewy bodies and Parkinson's disease dementia. This came up when routine clinical use of cholinesterase inhibitors in dementia patients with symptoms other than typical AD seemed to show a cognitive and clinical benefit in a large minority of such patients (Pakrasi et al., 2003). One multicenter, five-month trial in 120 patients with DLB showed a benefit on apathy, anxiety, delusions, hallucinations, as well as on cognitive performance and attention in the treatment group. About two-thirds of the treated patients had a clinically signifcant response to rivastigmine (McKeith et al., 2000). Hallucinations are a hallmark symptom of DLB and PDD and represent an area of overlap between these forms of dementia and AD; retrospective analysis of several trials indicates that AD patients with hallucinations respond better to rivastigmine treatment than those without (Cummings et al., 2010). More broadly, rivastigmine treatment appears to reduce somewhat the concomitant use of antipsychotic medications in people with AD (Scharre et al., 2010). How to manage behavioral symptoms of AD has become a pressing issue since 2005, when the FDA responded with a black-box warning to reports of increased mortality in dementia patients on antipsychotics (see Feb 2011 news storyOct 2005 news story).

The EXPRESS (EXelon in PaRkinson's disEaSe dementia Study) trial tested 3 to 12 mg/day of rivastigmine capsules in 541 patients with Parkinson's disease dementia, first for six months in a double-blind and placebo controlled phase, and then in an open-label extension. At six months, treated patients improved modestly on cognition, overall function, and psychiatric symptoms. By 48 weeks, the mean ADAS-cog score for the treatment group remained above baseline, and placebo patients who switched to rivastigmine for the extension phase had a treatment benefit similar to that of the original rivastigmine group during the double-blind trial. Again, patients with hallucinations tended to respond better (e.g., Poewe et al., 2006). Rivastigmine also appeared to improve apathy in patients with advanced PD who did not yet have dementia; this finding is from a small trial conducted in France (Devos et al., 2013).

More recently, Novartis ran an 18-month trial comparing the capsule and patch formulations in 583 patients with mild to moderately severe PDD. This trial specifically assessed whether long-term treatment with rivastigmine improves cognitive and psychiatric symptoms of PDD at the cost of worsening motor symptoms. Data from NCT00623103 are not published yet. Traditionally, cholinergic agents have been considered counterindicated for the motor and autonomic aspects of PD. This is in part because anticholinergic drugs have been used for the symptomatic treatment of PD since the late 19th century, particularly muscarinic receptor antagonists. This view is changing. Guidelines by the U.K. National Institute for Health and Clinical Excellence (NICE) challenge the evidence for the safety and effectiveness of anticholinergics in PD and recommend against their use as a first-line treatment in this disease, particularly in patients with cognitive dysfunction (see guideline).

Some studies indicate that rivastigmine may have an effect on cerebrovascular factors influencing dementia. Alzheimer's patients who also have cardiovascular risk factors such as hypertension have been reported to respond better to rivastigmine than patients with more "pure" Alzheimer's disease, and some evidence exists for a treatment benefit of rivastigmine for vascular dementia  (e.g., Erkinjuntti et al., 2003Farlow et al., 2011Birks et al., 2013).

For some years after cholinesterase inhibitor therapies were initially approved for Alzheimer's disease, their modest effect size created controversy about their cost-effectiveness (see Jul 2004 news story and extensive commentary). Since then, studies have shown that rivastigmine is modestly effective in the long-term treatment of AD, see above. Pharmacoeconomic studies in the United States and European countries have generally found that cholinesterase inhibitor treatment reduces the cost of care (e.g., Nagy et al., 2011). In the United Kingdom, where this debate had called into question coverage of rivastigmine by its universal health care system, NICE in 2011 issued a guidance recommending the use of rivastigmine in the treatment of mild to moderate AD (see, e.g., Fillit et al., 1999; Wimo et al., 2003; NICE guidance).

Rivastigmine is being evaluated in trials of Down's syndrome, mild cognitive impairment in Parkinson's disease, supranuclear palsy, delirium, traumatic brain injury, and cocaine dependence. For a list of rivastigmine trials, see clinicaltrials.gov.

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References

News Citations

  1. Warning on Antipsychotics Heeded, But What’s the Alternative?
  2. More Trouble for Atypical Antipsychotics—Dementia Patients at Risk
  3. Cholinesterase Inhibitors Not What They're Cracked Up To Be?

Paper Citations

  1. . For the ENA 713 B352 Study. A randomised trial evaluating the efficacy and safety of ENA 713 (rivastigmine tartrate), a new acetylcholinesterase inhibitor, in patients with mild to moderately severe Alzheimer’s disease. Int J Ger Psychopharmacol 1998. 155–65.65
  2. . Efficacy and safety of rivastigmine in patients with Alzheimer's disease: international randomised controlled trial. BMJ. 1999 Mar 6;318(7184):633-8. PubMed.
  3. . IDEAL: a 6-month, double-blind, placebo-controlled study of the first skin patch for Alzheimer disease. Neurology. 2007 Jul 24;69(4 Suppl 1):S14-22. PubMed.
  4. . Dose effects associated with rivastigmine transdermal patch in patients with mild-to-moderate Alzheimer's disease. Int J Clin Pract. 2011 Apr;65(4):465-71. PubMed.
  5. . A 24-Week, Randomized, Controlled Trial of Rivastigmine Patch 13.3 mg/24 h Versus 4.6 mg/24 h in Severe Alzheimer's Dementia. CNS Neurosci Ther. 2013 Oct;19(10):745-52. PubMed.
  6. . Real-life effectiveness and tolerability of the rivastigmine transdermal patch in patients with mild-to-moderate Alzheimer's disease: the EMBRACE study. Curr Med Res Opin. 2013 Aug;29(8):989-1000. PubMed.
  7. . Cognitive performance in Alzheimer's disease patients receiving rivastigmine for up to 5 years. Int J Clin Pract. 2005 Apr;59(4):473-7. PubMed.
  8. . Rivastigmine in Alzheimer disease: efficacy over two years. Am J Geriatr Psychiatry. 2004 Jul-Aug;12(4):420-31. PubMed.
  9. . A multinational, randomised, 12-week, comparative study of donepezil and rivastigmine in patients with mild to moderate Alzheimer's disease. Int J Clin Pract. 2002 Jul-Aug;56(6):441-6. PubMed.
  10. . Rivastigmine and donepezil treatment in moderate to moderately-severe Alzheimer's disease over a 2-year period. Curr Med Res Opin. 2005 Aug;21(8):1317-27. PubMed.
  11. . Clinical predictors of response to Acetyl Cholinesterase Inhibitors: experience from routine clinical use in Newcastle. Int J Geriatr Psychiatry. 2003 Oct;18(10):879-86. PubMed.
  12. . Efficacy of rivastigmine in dementia with Lewy bodies: a randomised, double-blind, placebo-controlled international study. Lancet. 2000 Dec 16;356(9247):2031-6. PubMed.
  13. . Effects of rivastigmine in Alzheimer's disease patients with and without hallucinations. J Alzheimers Dis. 2010;20(1):301-11. PubMed.
  14. . Use of antipsychotic drugs in patients with Alzheimer's disease treated with rivastigmine versus donepezil: a retrospective, parallel-cohort, hypothesis-generating study. Drugs Aging. 2010 Nov 1;27(11):903-13. PubMed.
  15. . Long-term benefits of rivastigmine in dementia associated with Parkinson's disease: an active treatment extension study. Mov Disord. 2006 Apr;21(4):456-61. PubMed.
  16. . Rivastigmine in apathetic but dementia and depression-free patients with Parkinson's disease: a double-blind, placebo-controlled, randomised clinical trial. J Neurol Neurosurg Psychiatry. 2014 Jun;85(6):668-74. Epub 2013 Nov 11 PubMed.
  17. . Potential long-term effects of rivastigmine on disease progression may be linked to drug effects on vascular changes in Alzheimer brains. Int J Clin Pract. 2003 Nov;57(9):756-60. PubMed.
  18. . The effect of vascular risk factors on the efficacy of rivastigmine patch and capsule treatment in Alzheimer's disease. Dement Geriatr Cogn Dis Extra. 2011 Jan;1(1):150-62. PubMed.
  19. . Rivastigmine for vascular cognitive impairment. Cochrane Database Syst Rev. 2013;5:CD004744. PubMed.
  20. . Assessing the cost-effectiveness of the rivastigmine transdermal patch for Alzheimer's disease in the UK using MMSE- and ADL-based models. Int J Geriatr Psychiatry. 2011 May;26(5):483-94. PubMed.
  21. . Donepezil use in managed Medicare: effect on health care costs and utilization. Clin Ther. 1999 Dec;21(12):2173-85. PubMed.
  22. . An economic evaluation of donepezil in mild to moderate Alzheimer's disease: results of a 1-year, double-blind, randomized trial. Dement Geriatr Cogn Disord. 2003;15(1):44-54. PubMed.
  23. . Pharmacokinetic rationale for the rivastigmine patch. Neurology. 2007 Jul 24;69(4 Suppl 1):S10-3. PubMed.

External Citations

  1. NCT00623103
  2. guideline
  3. NICE guidance
  4. clinicaltrials.gov
  5. Law360 story

Further Reading

Papers

  1. . Clinical trials of dementia with lewy bodies and Parkinson's disease dementia. Curr Neurol Neurosci Rep. 2012 Oct;12(5):492-501. PubMed.
  2. . A review on cholinesterase inhibitors for Alzheimer's disease. Arch Pharm Res. 2013 Apr;36(4):375-99. PubMed.
  3. . A meta-analysis of the efficacy of donepezil, rivastigmine, galantamine, and memantine in relation to severity of Alzheimer's disease. J Alzheimers Dis. 2013 Jan 1;35(2):349-61. PubMed.
  4. . The effectiveness and cost-effectiveness of donepezil, galantamine, rivastigmine and memantine for the treatment of Alzheimer's disease (review of Technology Appraisal No. 111): a systematic review and economic model. Health Technol Assess. 2012;16(21):1-470. PubMed.