Transcript Carnitine Overview

Carnitine Overview
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Carnitine: historical overview
1905
Carnitine is isolated from muscle tissue
1927
Identification of L-Carnitine chemical structure
CH3
H3C
N+
CH3
H
CH2
C
OH
CH2
_
COO
Background
Stimulation of fatty acid oxidation
Congenital carnitine metabolism disorders are discovered
L-Carnitine first launched in Italy
Carnitine’s role in acyl-group transfer is recognised
US FDA Orphan Drug designation:
1952
1973
1977
1978
1982
Sigma-Tau synthesizes the biologically active
L-carnitine and its derivative Acetyl-L-Carnitine
1985
1995
•
•
•
1984 *primary deficiency
1992 secondary deficiency
1999 dialysis deficiency
Sigma-Tau is the first inventor of L-Carnitine industrial
production process (Italian Patent no.1156852)
*second Orphan Drug Designation awarded by US FDA
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Carnitine
• Carnitine is an endogenous quaternary
compound that is synthesised from amino
acids lysine and methionine, reaction
catalyzed by γ-butyrobetaine hydroxylase.
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Carnitine sources
25% of free L-carnitine is synthesized in liver and kidney where enzyme
γ-butyrobetaine hydroxylase is highly expressed.
75% of free L-carnitine, is absorbed from dietary intake.
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Carnitine/Acetyl-L-Carnitine ratio in fluid
Plasma concentration of
free carnitine is in
dynamic balance with
acylcarnitines with the
acyl to free Carnitine
ratio of ≤ 0.4 being
considered normal.
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Carnitine System Overview - PB – 29.03.2013
Cellular localization of Carnitine system
enzymes and proteins
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The essential role of Carnitine
• Fatty acid transport and oxidation
• Detoxification of toxic metabolites
• Regulation of the mitochondrial acyl-CoA/CoA ratio
• Stabilization of cell membranes
• Balance glucose & fatty acid oxidation
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Fatty acid transport and oxidation
Carnitine is the only one transporter.
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Acyl-CoA-Synthetase
Long-chain fatty acids (>12 C) are extracted from triglycerides by an
intracellular lipase. Fatty acids are then activated by Acyl-CoA
Synthetase, located in the outer mitochondrial membrane.
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Carnitine Palmitoyl-Transferase I
Carnitine
The Carnitine Palmitoyl - Transferase I
catalyzes the transfer of acyl groups from activated fatty acid (acyl-CoA) to
carnitine, forming acylcarnitine and releasing CoA in cytoplasm
Acyl-CoA
CPT I
CoA + Acyl-L-carnitine
Acyl CoA + L-carnitine
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Carnitine System Overview - PB – 29.03.2013
Carnitine Translocase
The Carnitine–acylcarnitine translocase
carries a molecule of cytosolic acylcarnitine within the mitochondrion
exchanging it with one molecule of free carnitine present in the
mitochondrion, that is transported in the cytosol.
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Carnitine System Overview - PB – 29.03.2013
Carnitine Palmitoyl-Transferase II
The Carnitine Palmitoyl - Transferase II
is located on the inner side of mitochondrial matrix. It converts
acylcarnitine in acyl-CoA and L-Carnitine.
Acyl-carnitine + CoA
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CPT II
Acyl-CoA + L-carnitine
Energy production
Finally the acyl-CoA is conveyed to the
beta-oxidation and fragmented in chains
containing two Carbons (acetyl-CoA),
which subsequently enter in the Krebs
cycle, the Electron Transport Chain, with
the final result of energy production
(ATP).
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Carnitine System Overview - PB – 29.03.2013
L-Carnitine: Mechanism of Action
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Detoxification of toxic metabolites
Long chain fatty acids then
accumulate and become cytotoxic by
degrading cellular membranes and
inhibiying enzymes.
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Regulation of the mitochondrial
Acyl-CoA/ CoA ratio
• Free CoA is an essential element in the cell’s metabolic pathsways, cell
membranes are impermeable to CoA.
• Carnitine controls intracellular/intramitochondrial concentrations of acyl-CoA
and free CoA.
Acyl CoA + L-carnitine
CoA + Acyl-L-carnitine
Free CoA regulates mitochondrial key-enzymes
(pyruvate dehydrogenase and beta-oxidation dehydrogenases),
which control lipid and glucose metabolism.
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Stabilization of cell membranes
Carnitine has a stabilizing effect on cell membranes, regulates the
turnover of damaged fatty acids within the phospholipid membranes
(ie, after oxidative stress insult).
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Mitochondrial carnitine pathway
interplay between lipid and glucose metabolism
Indications for L-Carnitine
Cardiovascular disease
Sport
Renal insufficiency
Pregnancy/
Delivery
Immunedeficits
Inborn metabolic
errors
L-Carnitine
Fatigue/Chronic
Fatigue Syndrome
(CFS)
Muscle
diseases
Cancer
Nutritional
deficits
Diabetes
Infertility
Carnitine Primary Deficiency
•
Primary deficiency: a genetic defect in the transport of Carnitine across
the cell membrane: OCTN2.
Carnitine
Secondary deficiencies
Inborn errors of Metabolism
Drug-induced Carnitine deficiency
 Organic acidurias –amino acid oxidation errors
Physiopathologically-induced Carnitine
deficiency:
 Fatty acid oxidation defects:
 Carnitine system enzyme defects
 Beta oxidation defects
 Mitochondrial respiratory chain enzyme defects
 Dys-Metabolism
 Myocardial Infarction
 Haemodialysis
FDA approval
based on the Clinical Cases
of Prof Susan Winter
L-Carnitine: seven orphan drug status in the USA
February 1984
L-Carnitine in the treatment of genetic Carnitine Deficiency
July 1984
L-Carnitine in the treatment of primary and secondary Carnitine Deficiency
of genetic origin
September 1988
L-Carnitine in the treatment of manifestation of Carnitine Deficiency in
patients with end stage renal disease who require dialysis
November 1989
L-Carnitine for prevention of secondary Carnitine Deficiency in valproic
acid toxicity
November 1989
L-Carnitine in the treatment of secondary Carnitine Deficiency in valproic
acid toxicity
November 1993
L-Carnitine in the treatment of pediatric cardiomyopathy
April 1997
L-Carnitine in the treatment of Zidovudine-induced mitochondrial
myopathy
Methylmalonic Aciduria
mutase 0 (MMA)
Isoleucine ,valine, methionine
threonine
Propionyl CoA
Methylmalonyl CoA
X
Succinyl CoA (TCA Cycle)
Initial Patient Experience
• 1982- MMA mut0-neonatal onset
– Results in increased excretion of propionyl carnitine (not
understood in 1982)
– Only treatment in 1982 was dietary and supportive
– Long term prognosis fatal
•
Rousson T, Guibaud P. Long term outcome of organic acidurias:survey of 105 French cases (1967-1983) J Inherit Metab
Dis 1984;7 Suppl 1:10-2
– 1983/1984-Carnitine treatment
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Roe CR, Hoppel CL, Stacey TE, Chalmers RA, Tracey BM, Millington DS. Metabolic response to carnitine in methylmalonic
aciduria. An effective strategy for elimination of propionyl groups. Arch Dis Child 1983 Nov;58(11):916-20
•
Chalmers RA, Stacey TE, Tracey BM, de Sousa C, Roe CR, Millington DS, Hoppel,C. L-Carnitine insufficiency in disorders
of organic acid metabolism: response to L-carnitine by patients with methylmalonic aciduria and 3-hydroxy-3-methylglutaric
aciduria.J Inherit Metab Dis. 1984;7 Suppl 2:109-10
Carnitine Values
Plasma
Micromoles/liter
 Total -
17.4
 Normal (30-70)
 Free -
7.9
 Normal (25-65)
 Ester -
9.5
 Normal (0-10)
Urine
Micromoles/liter
53.1
 Normal (300-360)
7.5
 Normal (140-200)
45.6
 Normal (140-200)
Metabolic Analysis Laboratory. Austin Shug, PhD
Weight gain
First 36 Cases of Carnitine Deficiency
(1965-1987)
• Encephalopathy (77%)
• Progressive Muscle Weakness (77%)
• Lipid Excess in Muscle (100%)
• Cardiomyopathy (23%)
• Low Serum Carnitine (89%)
• Low Muscle Carnitine (100%)
Plasma Carnitine Deficiency
51 Cases
• Hypotonia/ gross motor delay (85%)
• Recurrent infections with metabolic
decompensations (85%)
• Failure to thrive (75%)
• Mental retardation (40%)
• Cardiomyopathy (30%)
• Encephalopathy (5%)
Winter SC et al. Am J Dis Child 1987;141:660.
Medium Chain Fatty Acyl CoA
Dehydrogenase Deficiency (MCAD)
FDA approval of Carnitine for Inborn Errors of
Metabolism
• 1985- oral carnitine approved by FDA for
treatment of primary carnitine deficiency
• 1992-NDA for treatment for secondary carnitine
deficiency due to IEM based on retrospective data
 Limited to disorders where Acyl CoA metabolites accumulate
Summary of Data
• Significant drop in hospitalization frequency for
all groups
• Significant increase in survival
• Significant improvement in failure to thrive
• Significant change in biochemical parameters
– Improved ketosis-restoration of beta oxidation
– Increased excretion of accumulating acyl groups
– Positive effect on Acyl CoA/Free CoA ratio
RB – Age 10 Years
MMA Mut 0
RB – Effect of Carnitine PO and IV on Plasma
Carnitine Metabolites
Carnitine intake
(mg/kg/day)
Plasma carnitine
(mmol/L)
Date
Oral
IV
Total
Free
Ester
6/13
400
0
87.6
7.2
80.4
6/16
0
200
170.0
63.4
106.6
6/21
400
300
396.7
304.0
92.7
6/26
666
300
523.5
338.8
134.7
6/30
666
0
186.5
94.6
91.9
10 years on IV carnitine therapy
6 months on IV carnitine therapy
Glutaric Aciduria II-ETF
GA II patient when
diagnosed and
started on IV
carnitine, riboflavin,
and protein/fat
restricted diet
Same patient
after 10 days
of carnitine,
riboflavin and
diet
Patient at Age 14 Remaining well on
L-Carnitine treatment
Valproic Acid,
Hepatic Failure
and Carnitine
Deficiency
Drug induced Carnitine Deficiency:
Valproate
Survival (%)
The survival of patients with VPA hepatotoxicity gets worse the longer the
valproate is continued: comparison of L-carnitine–treated patients with
untreated patients
100
L-Carnitine treated
80
Untreated controls
60
40
20
0
Hepatotoxic episode duration before valproate stopped
Reproduced with permission from Lippincott, Williams & Wilkins. Bohan TP.
Neurology. 2001;56:1405-1409.
The essential role of Carnitine
• Life-saving
• Key role in healthy metabolism
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谢谢
Thank You
L-Carnitine