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L-Carnitine



Interactions

Carnitine/Drug Interactions:
  • Adefovir dipivoxilAdefovir dipivoxil: Based on a clinical trial, adefovir dipivoxil may reduce free carnitine levels (68).
  • AdriamycinAdriamycin: Based on animal studies, carnitine may prevent arrhythmias provoked by adriamycin (69).
  • AntiarrhythmicsAntiarrhythmics: Based on a clinical trial of angina patients, L-carnitine may decrease the need for antiarrhythmics (9).
  • AnticoagulantsAnticoagulants: Based on a clinical trial of angina patients, L-carnitine may decrease the need for anticoagulants (9).
  • Anticonvulsants (phenobarbital, phenytoin, carbamazepine)Anticonvulsants (phenobarbital, phenytoin, carbamazepine): Decreased serum carnitine has been noted in children using these medications (70).
  • Antidiabetic drugsAntidiabetic drugs: Increased triglycerides, increased ApoB 100, increased Apo A1, and decreased glucose were found in individuals with diabetes using L-carnitine (6). Carnitine levels did not change in diabetics with insulin or sulfonylurea therapy (71).
  • Beta-blockersBeta-blockers: Based on a clinical trial of angina patients, L-carnitine may decrease the need for beta-blockers (9).
  • Calcium channel blockersCalcium channel blockers: Based on clinical trials of angina patients, L-carnitine may decrease the need for calcium channel blockers (8; 9).
  • CephalosporinCephalosporin: Clinical studies with S-1108 suggest this drug may reduce plasma carnitine levels (72; 73).
  • CinnoxicamCinnoxicam: L-carnitine plus acetyl-L-carnitine plus cinnoxicam are more effective in improving sperm parameters as compared with L-carnitine plus acetyl-L-carnitine alone (74).
  • CisplastinCisplastin: Based on a case series, cisplastin may increase urinary excretion of carnitine, but the loss did in the study did not exceed 3-5% and was easily replenished with food (75). Based on a case series, carnitine may reduce neuropathy symptoms associated with cisplastin use (60), as well as diminish fatigue (76).
  • DigoxinDigoxin: Based on a clinical trial of congestive heart failure patients, L-carnitine may decrease the need for digoxin (20).
  • DiureticsDiuretics: Based on a clinical trial of angina patients, L-carnitine may decrease the need for diuretics (9). In a study of patients with left ventricular dysfunction, no adverse effects were noted when diuretics were used with carnitine (21).
  • GlycosidesGlycosides: Based on a clinical trial of angina patients, L-carnitine may decrease the need for glycosides (9).
  • Hypolipidemic drugsHypolipidemic drugs: Based on a clinical trial of angina patients, L-carnitine may decrease the need for hypolipidemic drugs (9).
  • IfosfamideIfosfamide: Increased urinary loss of carnitine has been noted. During one chemotherapy cycle patients lost about 10% of their carnitine stores in a clinical trial (77). Carnitine has been suggested to reduce fatigue associated with ifosfamide (76).
  • Interleukin-2Interleukin-2: Based on a randomized controlled trial of cancer patients, L-carnitine supplementation may reduce side effects associated with IL-2 (78)
  • IsotretinoinIsotretinoin: Based on a clinical study, supplementation with carnitine may improve liver and muscular side effects associated with isotretinoin in acne patients (79).
  • Nitro derivativesNitro derivatives: Based on a clinical trial of angina patients, L-carnitine may decrease the need for nitro derivatives (9).
  • NortryptilineNortryptiline: Based on a study in rabbits, carnitine may prevent widening of PQ and QRS intervals in ECG caused by nortriptyline (80).
  • Nucleoside analoguesNucleoside analogues: In a clinical trial, subjects suffering from neuropathy induced by nucleosides had significantly reduced levels of acetyl carnitine compared to the control group (81).
  • PaclitaxelPaclitaxel: Based on a case series, carnitine may reduce neuropathy symptoms associated with paclitaxel use (60).
  • Penicillin derivatives (Pivaloyloximethyl-esterified; pivampicillin and pivmecillinam)Penicillin derivatives (Pivaloyloximethyl-esterified; pivampicillin and pivmecillinam): Based on two clinical studies, penicillin derivatives may decrease in serum carnitine concentration, elevate excretion of acyl-carnitine, and reduce muscle carnitine concentration (82; 83). No clinical signs of carnitine deficiency were reported. In seven children pivampicillin treatment reduced levels of total carnitine, free carnitine, and acylcarnitines (84).
  • Potassium chloridePotassium chloride: Based on a case study, L-carnitine chloride and KCl may minimize rhabdomyolysis associated with liquorice ingestion (85).
  • PropafenonePropafenone: Based on a randomized controlled trial, carnitine plus propafenone may improve arrythmia better than propafenone alone (48).
  • SildenafilSildenafil: Based on a randomized controlled trial, sildenafil and propionyl-L-carnitine may be more effective than sildenafil alone (86).
  • Valproic acidValproic acid: In animal studies free valproic acid concentrations in the brain were significantly increased by carnitine, potentially increasing effects associated with valproic acid (87). In humans, treatment with carnitine returned the prolonged half-lives of valproic acid, associated with carnitine deficiency, close to the normal range (88). In a clinical trial,t plasma carnitine concentrations were lower and blood ammonia values were higher in patients treated with valproic acid than in the untreated patients and control subjects (89). In children treated with valproic acid a significant reduction was found in muscle carnitine content (90). Treatment with carnitine improves carnitine levels in children treated with valproate and has no effect on plasma valproic acid levels (91). One case study suggests carnitine supplementation had no effect on valproate-related hepatotoxic effects (92).
  • Zidovudin (AZT)Zidovudin (AZT): In myotubes of human muscle in tissue culture, AZT induced depopulation of myotubes and destructive changes in mitochondria. L-carnitine used concurrently with AZT prevented all these effects (93).

Carnitine/Herb/Supplement Interactions:
  • AnticoagulantsAnticoagulants: Based on a clinical trial of angina patients, L-carnitine may decrease the need for anticoagulants (9).
  • Antidiabetic herbsAntidiabetic herbs: Increased triglycerides, increased ApoB 100, increased Apo A1, and decreased glucose were found in individuals with diabetes using L-carnitine (6). Carnitine levels did not change in diabetics with insulin or sulfonylurea therapy (71).
  • CholineCholine: Based on a clinical study of healthy humans, choline supplementation may reduce excretion, renal clearance, and fractional clearance of non-esterified carnitine (94).
  • DiureticsDiuretics: Based on a clinical trial of angina patients, L-carnitine may decrease the need for diuretics (9). In a study of patients with left ventricular dysfunction, no adverse effects were noted when diuretics were used with carnitine (21).
  • LicoriceLicorice: Based on a case study, L-carnitine chloride and KCl may minimize rhabdomyolysis associated with licorice ingestion (85).

Carnitine/Food Interactions:
  • Breast milkBreast milk: Based on a clinical trial, breast-fed infants may have higher carnitine plasma levels and as a consequence to higher ketone body production than formula-fed infants (95).
  • CholineCholine: Based on a controlled trial, serum and urinary carnitine may decrease with choline supplementation (96).
  • Lipid preparationsLipid preparations: Based on a clinical trial, lipid preparations administered intravenously to malnourished patients may strongly depress urinary carnitine excretion (97). Based on a clinical trial, urinary excretion of acyl-carnitine may be significantly higher and free/total carnitine ratio may be lower in infants ingesting formula containing medium-chain fatty acids (triglycerides) (98).
  • Low proteinLow protein: Based on a crossover clinical study, the rates of carnitine excretion and reabsorption may be lower after a low protein diet than after a high protein diet because of the lower glomerular filtration rate (99).

Carnitine /Lab Interactions:
  • 3-hydroxybutyrate3-hydroxybutyrate: Increases have been noted in infants (100; 101; 102; 103).
  • Anabolic hormonesAnabolic hormones: Based on a study of 10 healthy, recreationally weight-trained men, L-carnitine L-tartrate may significantly increase IGFBP-3 concentrations prior to and at 30, 120, and 180 minutes after acute supplementation (104).
  • Aspartate transaminaseAspartate transaminase: Based on a randomised, double-blind placebo controlled trial, L-carnitine may decrease serum aspartate transaminase levels (40).
  • CarnitineCarnitine: In rats, treatment with L-carnitine restored levels of plasma carnitine (105). Based on a clinical trial, muscle carnitine concentration at rest may not change due to carnitine supplementation (106). In a study of healthy vegans and lacto-ovo-vegetarians, carnitine supplementation increased plasma free and total carnitine concentrations by 30 and 25%, respectively (107). Increase in blood carnitine and acylcarnitine, blood and urinary acetyl-carnitine, and red blood cell and muscle carnitine have been shown by other authors in various populations, including preterm and term infants (100; 108; 109; 11; 110; 111; 112; 42; 96; 101; 113; 102; 114; 115; 116; 117; 118). A decrease in free and total carnitine has been noted in premature infants (117).
  • Based on a study of newborn infants on total parenteral nutrition (Intralipid) for the first seven days of life, Intralipid may increase plasma concentration of total carnitine, free carnitine, and acyl carnitine (119).
  • CreatinineCreatinine: Based on a randomized controlled study in hemodialysis patients, carnitine levels may be decreased (120).
  • Cytosolic proteinsCytosolic proteins: Based on a study in resistence-trained men, exercise-induced increases in circulating cytosolic proteins (myoglobin, fatty acid-binding protein, and creatine kinase) may be significantly attenuated by L-carnitine L-tartrate supplementation (121).
  • Free fatty acidsFree fatty acids: An increase in free fatty acids in premature infants has been noted (116). An increase was noted in full term infants (115). A decrease has been noted in patients with coronary artery disease and in top athletes (122; 123).
  • GlucoseGlucose: In rats, treatment with L-carnitine reduced plasma glucose (105). In healthy volunteers, carnitine was able to reduce the increase in plasma glucose levels induced by glucose infusion (124). In preterm infants, glucose levels increased (125). Decreased glucose was noted in diabetic individuals given L-carnitine (6).
  • GlutamateGlutamate: Breitkreutz (126) has reported that carnitine use in cancer patients may increase plasma glutamate levels.
  • GlycerolGlycerol: An increase in glycerol in premature infants has been noted (116).
  • InsulinInsulin: In rats, treatment with L-carnitine had no effect on insulin levels (105). In healthy subjects a decrease in insulin levels with L-carnitine was noted (127).
  • Ketone bodiesKetone bodies: An increase in ketone bodies in premature infants has been noted (116).
  • LactateLactate: Both an increase and decrease have been noted after exercise (33; 128). No change has been noted (122). A decrease was noted in septic patients on parenteral nutrition (111).
  • Markers of purine catabolismMarkers of purine catabolism: Exercise-induced increases in plasma markers of purine catabolism (hypoxanthine, xanthine oxidase, and serum uric acid) were significantly attenuated by L-carnitine L-tartrate supplementation (121).
  • PhosphorousPhosphorous: A slight decrease has been noted in hemodialysis patients (120).
  • Plasma lipidsPlasma lipids: Carnitine was reported to reduce the level of serum triglycerides in patients with hyperlipidemia (129; 130). Decreased triglycerides were also found in infants (102; 115) and other populations (9; 11; 131; 20; 132; 123). Increased triglycerides, Apo B100 and Apo A1 were found in individuals with diabetes on glyburide or metformin (6). Increased triglycerides were also noted in uremic patients on hemodialysis (7). Decreased cholesterol has been noted (9; 133; 131; 20). Increased HDL has been noted (133; 134; 135; 131; 132). Decreased total cholesterol to HDL cholesterol ratio has been noted (134; 135). No changes in Apo A1 or Apo B were noted in hypertensive individuals (131). No changes in triglycerides, total cholesterol, HDL-cholesterol, ApoA and Apo B were noted in one study (112). No changes in total cholesterol were noted in patients with hemodialysis (132).
  • Plasma fatty acidsPlasma fatty acids: Carnitine supplementation did not affect eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content (107). Use of a new lipid emulsion containing carnitine, in infants, resulted in a decrease in DHA and arachidonic acid (AA) (113).
  • Plasminogen activator inhibitor-1Plasminogen activator inhibitor-1: A decrease has been noted with clinical use of propionyl-L-carnitine (43; 43)
  • Platelet aggregationPlatelet aggregation: An increased in platelet aggregation ex vivo was noted in uremic patients on hemodialysis (7).
  • PotassiumPotassium: No change was noted in one clinical trial (131).
  • PyruvatePyruvate: A decrease was noted in septic patients on parenteral nutrition (111).
  • Serum myoglobinSerum myoglobin: A decrease was noted in a clinical trial of L-carnitine (136).
  • SodiumSodium: No change was noted in one clinical trial (131).
  • TNFalphaTNFalpha: A decrease has been noted in HIV patients (11).
  • Urea nitrogenUrea nitrogen: A slight decrease has been noted in hemodialysis patients (120).
  • White blood cell countsWhite blood cell counts: Increased CD4 and CD8 lymphocyte counts have been noted in some individuals with HIV-1 infection who have not been treated with antiretroviral therapy (137).

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

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