No report of overdose has been received from the RHODOS study.
There is no specific antidote for idebenone. When needed, supportive symptomatic treatment should be given.
Not applicable.
Summary of the safety profile
The most commonly reported adverse reactions to idebenone are mild to moderate diarrhoea (usually not requiring the discontinuation of the treatment), nasopharyngitis, cough and back pain.
Tabulated list of adverse reactions
The following adverse reactions emerging from clinical trials in LHON patients or reported post-marketing in other indications are tabulated below. Frequency groupings are defined to the following convention: very common (>1/10), common (>1/100 to <1/10), not known (cannot be estimated from the available data).
| System Organ Class | Preferred Term | Frequency |
| Infections and Infestations | Nasopharyngitis | Very common |
| Bronchitis | Not known | |
| Blood and lymphatic system disorders | Agranulocytosis, anaemia, leukocytopenia, thrombocytopenia, neutropenia | Not known
|
| Metabolism and nutrition disorders | Blood cholesterol increased, blood triglycerides increased | Not known |
| Nervous system disorders | Seizure, delirium, hallucinations, agitation, dyskinesia, hyperkinesia, poriomania, dizziness, headache, restlessness, stupor | Not known |
| Respiratory, thoracic and mediastinal disorders | Cough | Very common |
| Gastrointestinal disorders | Diarrhoea | Common |
| Nausea, vomiting, anorexia, dyspepsia | Not known | |
| Hepatobiliary disorders | Alanine aminotransferase increased, aspartate aminotransferase increased, blood alkaline phosphatase increased, blood lactate dehydrogenase increased, gamma- lutamyltransferase increased, blood bilirubin increased, hepatitis | Not known |
| Skin and subcutaneous tissue disorders | Rash, pruritus | Not known |
| Musculoskeletal and connective tissue disorders | Back pain | Common |
| Pain in extremity | Not known | |
| Renal and urinary disorders | Azotaemia, chromaturia | Not known |
| General disorders and administration site conditions | Malaise | Not known |
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the national reporting system:
United Kingdom
Yellow Card Scheme
Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store
Ireland
HPRA Pharmacovigilance
Earlsfort Terrace
IRL - Dublin 2
Tel: +353 1 6764971
Fax: +353 1 6762517
Website: www.hpra.ie
e-mail: [email protected]
Idebenone is indicated for the treatment of visual impairment in adolescent and adult patients with Leber's Hereditary Optic Neuropathy (LHON).
Pharmacotherapeutic group: Psychoanaleptics, Other psychostimulants and nootropics;
ATC code: N06BX13
Idebenone, a short-chain benzoquinone, is an anti-oxidant assumed to be capable of transferring electrons directly to complex III of the mitochondrial electron transport chain, thereby circumventing complex I and restoring cellular energy (ATP) generation under experimental conditions of complex I deficiency. Similarly, in LHON idebenone can transfer electrons directly to complex III of the electron transport chain, thereby bypassing complex I which is affected by all three primary mtDNA mutations causing LHON, and restoring cellular ATP generation.
According to this biochemical mode of action, idebenone may re-activate viable-but-inactive retinal ganglion cells (RGCs) in LHON patients. Depending on the time since symptom onset and the proportion of RGCs already affected, idebenone can promote recovery of vision in patients who experience vision loss.
Clinical safety and efficacy of idebenone in LHON have been assessed in one double-blind, randomised, placebo-controlled study (RHODOS).
In RHODOS a total of 85 LHON patients, 14-66 years of age, with any of the 3 primary mtDNA mutations (G11778A, G3460A or T14484C) and disease duration of not more than 5 years were enrolled. Patients received either 900 mg/day Idebenone or placebo for a period of 24 weeks (6 months). Idebenone was given as 3 daily doses of 300 mg each with meals.
The primary endpoint “best recovery of visual acuity (VA)†was defined as the result from the eye experiencing the most positive improvement in VA from baseline to week 24 using ETDRS charts. The main secondary endpoint “change in best VA†was measured as the difference between best VA in either the left or right eye at 24 weeks compared to baseline (Table 1).
Table 1: RHODOS: Best recovery of VA and change in best VA from baseline to week 24
| Endpoint (ITT) | Idebenone (N=53) | Placebo (N=29) |
| Primary endpoint: Best recovery of VA (mean ± SE; 95%CI) | logMAR -0.135 ± 0.041 | logMAR -0.071 ± 0.053 |
| logMAR -0.064, 3 letters (-0.184; 0.055) p=0.291 | ||
| Main secondary endpoint: Change in best VA (mean ± SE; 95% CI) | logMAR -0.035 ± 0.046 | logMAR 0.085 ± 0.060 |
| logMAR -0.120, 6 letters (-0.255; 0.014) p=0.078 | ||
Analysis according to Mixed Model of Repeated Measures
One patient in the placebo group presented with ongoing spontaneous recovery of vision at baseline. Exclusion of this patient yielded similar results as in the ITT population; as could be expected, the difference between idebenone and placebo arm was slightly larger.
A pre-specified analysis in RHODOS determined the proportion of patients with an eye with baseline VA of ≤0.5 logMAR in whom the VA deteriorated to >1.0 logMAR. In this small subgroup of patients (n=8), 0 of 6 patients in the idebenone group deteriorated to >1.0 logMAR whereas 2 of 2 patients in the placebo group showed such a deterioration.
In a single-visit observational follow-up study of RHODOS VA assessments from 58 patients obtained on average 131 weeks after discontinuation of treatment indicates that the effect of Idebenone may be maintained.
A post-hoc responder analysis was performed in RHODOS evaluating the proportion of patients who had a clinically relevant recovery of VA from baseline in at least one eye, defined as either: (i) improvement in VA from unable to read a single letter to able to read at least 5 letters on the ETDRS chart; or (ii) improvement in VA by at least 10 letters on the ETDRS chart. Results are shown in Table 2 including supporting data from 62 LHON patients using Idebenone in an Expanded Access Programme (EAP) and from 94 untreated patients in a Case Record Survey (CRS).
Table 2: Proportion of patients with clinically relevant recovery of VA after 6 months from baseline
| RHODOS (ITT) | RHODOS Idebenone (N=53) | RHODOS Placebo (N=29) |
| Responders (N, %) | 16 (30.2 %) | 3 (10.3 %) |
| EAP and CRS | EAP-Idebenone (N=62) | CRS-untreated (N=94) |
| Responders (N, %) | 19 (30.6 %) | 18 (19.1 %) |
In the EAP the number of responders increased with longer treatment duration, from 19 out of 62 patients (30.6%) at 6 months to 17 out of 47 patients (36.2%) at 12 months.
Paediatric population
In clinical trials in Friedreich's Ataxia, 32 patients between the ages of 8 and 11 years and 91 patients between the ages of 12 and 17 years received idebenone at > 900 mg/day for up to 42 months.
In RHODOS and the EAP in LHON, a total of 3 patients between the ages of 9 and 11 years and 27 patients between the ages of 12 and 17 years received idebenone at 900 mg/day for up to 33 months.
This medicinal product has been authorised under 'exceptional circumstances'.
This means that due to the rarity of the disease it has not been possible to obtain complete information on this medicinal product.
The European Medicines Agency will review any new information which may become available every year and this SmPC will be updated as necessary.
Absorption
Food increases the bioavailability of idebenone by approximately 5-7-fold and therefore, Idebenone should always be administered with food. The tablets should not be broken or chewed.
After oral administration of Idebenone, idebenone is rapidly absorbed. On repeat dosing, maximum plasma concentrations of idebenone are reached on average within 1 hour (median 0.67 h range: 0.33-2.00 h). In phase I pharmacokinetic studies, proportional increases in plasma concentrations of idebenone were observed for doses from 150 mg to 1050 mg. Neither idebenone nor its metabolites showed time-dependent pharmacokinetics.
Distribution
Experimental data have shown that idebenone passes the blood-brain barrier and is distributed at significant concentrations in cerebral tissue. Following oral administration pharmacologically relevant concentrations of idebenone are detectable in the aqueous humor of the eye.
Biotransformation
Metabolism occurs by means of oxidative shortening of the side chain and by reduction of the quinone ring and conjugation to glucuronides and sulphates. Idebenone shows a high first pass metabolism resulting in conjugates of idebenone (glucuronides and sulphates (IDE-C)) and the Phase I metabolites QS10, QS6, and QS4 as well as their corresponding Phase II metabolites (glucuronides and sulphates (QS10+QS10-C, QS6+QS6-C, QS4+QS4-C)). The main metabolites in plasma are IDE-C and QS4+QS4-C.
Elimination
Due to the high first-pass effect, the plasma concentrations of idebenone were generally only measurable up to 6 hours after oral administration of 750 mg Idebenone, given either as a single oral dose or after repeated (14 days) t.i.d dosing. The main route of elimination is metabolism, with the majority of dose excreted via the kidneys as metabolites. After a single or repeated oral dose of 750 mg Idebenone, QS4+QS4-C were the most prominent idebenone-derived metabolites in urine, representing on average between 49.3% and 68.3% of the total administered dose. QS6+QS6 represented 6.45% to 9.46%, whereas QS10+QS10-C and IDE+IDE-C were close to 1% or below.
Hepatic or renal impairment
No data are available in these populations.
Paediatric population
Whilst clinical trials experience in paediatrics with LHON is limited to patients of 14 years of age and above, pharmacokinetic data from population pharmacokinetic studies, which included paediatric Friedreich's Ataxia patients of age 8 years and above, did not reveal any significant differences in the pharmacokinetics of idebenone.
Monitoring
Patients should be regularly monitored according to local clinical practice.
Hepatic or renal impairment
No data are available in these populations. Therefore, caution should be exercised when prescribing Idebenone to patients with hepatic or renal impairment.
Chromaturia
The metabolites of idebenone are coloured and may cause chromaturia, i.e. a reddish-brown discoloration of the urine. This effect is harmless, not associated with haematuria, and does not require any adaptation of dose or discontinuation of treatment. Caution should be exercised to ensure that the chromaturia does not mask changes of colour due to other reasons (e.g. renal or blood disorders).
Lactose
Idebenone contains lactose. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take Idebenone.
Sunset yellow
Idebenone contains sunset yellow (E110) which may cause allergic reactions.
Idebenone has no or negligible influence on the ability to drive and use machines.
Treatment should be initiated and supervised by a physician with experience in LHON.
Posology
The recommended dose is 900 mg/day idebenone (300 mg, 3 times a day).
No data regarding a continuous treatment with idebenone beyond 6 months is available from controlled clinical trials.
Special populations
Elderly
No specific dose adjustment is required for the treatment of LHON in elderly patients.
Hepatic or renal impairment
Patients with hepatic or renal impairment have not been investigated. Caution is advised in treatment of patients with hepatic or renal impairment.
Paediatric population
The safety and efficacy of Idebenone in LHON patients under 12 years of age have not yet been established.2, but no recommendation on posology can be made.
Method of administration
Idebenone film-coated tablets should be swallowed whole with water. The tablets should not be broken or chewed. Idebenone should be administered with food because food increases the bioavailability of idebenone.
Any unused medicinal product or waste material should be disposed of in accordance with local requirements.
