MEDICAL DISCLAIMER: Educational research guidelines only. Lyophilized peptides are investigational chemical compounds and are NOT approved for human consumption, diagnosis, or therapy. Consult a licensed physician before any research application.
L-Carnitine Dosage Chart, Schedule & Reconstitution Protocol
Quickstart Highlights
L-Carnitine is a quaternary ammonium compound synthesized endogenously from lysine and methionine that serves as an obligate cofactor for the carnitine palmitoyltransferase (CPT-1/CPT-2) shuttle, which transports long-chain fatty acyl-CoA into the mitochondrial matrix for beta-oxidation. It also buffers excess acyl-CoA, supports branched-chain amino acid metabolism, and contributes to membrane stability. Levocarnitine (the L-isomer) is FDA-approved for primary and secondary carnitine deficiency, including dialysis-associated deficiency, and is studied for cardiovascular outcomes after myocardial infarction, male fertility, diabetic neuropathy, and exercise performance [PMID: 23597933][PMID: 21366839]. Oral, IM, and IV preparations are widely available; subcutaneous use is off-label. Effects on body composition in non-deficient individuals are modest and require chronic dosing on the order of weeks to months to raise muscle carnitine content.
Reconstitute: Add 2 mL bacteriostatic water → 100 mg/mL concentration.
Easy measuring: At 100 mg/mL, 1 unit = 0.01 mL = 1 mg (1000 mcg) on a U-100 insulin syringe.
Storage: Lyophilized frozen; reconstituted refrigerated; avoid repeated freeze–thaw cycles.
Approved deficiency indication: Levocarnitine is FDA-approved (Carnitor) for primary systemic carnitine deficiency and for secondary deficiency in patients on hemodialysis. Cosmetic or performance use is off-label.
TMAO and cardiovascular concern: Gut microbiota convert dietary and supplemental L-carnitine to trimethylamine, which is hepatically oxidized to TMAO. Elevated TMAO has been linked in observational studies to atherosclerosis risk, though the clinical significance for supplement users remains debated.
Acetyl-L-carnitine vs L-carnitine: ALCAR crosses the blood-brain barrier more readily and is studied for cognition, neuropathy, and mood; plain L-carnitine and L-carnitine L-tartrate are preferred for skeletal-muscle fatty acid oxidation and exercise applications.
Quick Protocol Navigation
Reconstitution Instruction & Mixing Step-by-Step
Lyophilized powder must be reconstituted carefully. Agitating peptide chains can shear disulfide bonds and render the peptide biologically inert.
Draw 2.0 mL bacteriostatic water (0.9% benzyl alcohol) with a sterile syringe.
Inject slowly down the vial wall to minimize foaming; avoid direct stream onto powder.
Gently swirl or roll the vial until powder is fully dissolved (do not shake vigorously).
Injection speed: Inject slowly (over several seconds) to minimize discomfort; wait 5–10 seconds before withdrawing needle to prevent leakage[6].
Inject slowly: Depress plunger steadily over 3–5 seconds to minimize discomfort. Injecting volumes <1.0 mL causes minimal pain; larger volumes (1.5–2.0 mL) may be split into two separate injections[6].
Interactive L-Carnitine Syringe Calculator
Currently visualizing the 200 mg vial reconstituted with 2 mL bacteriostatic water. Adjust the target dose to dynamically render syringe units.
Reconstitution Calculation: 200mg dry powder in 2mL water yields 100.00 mg/mL. To evaluate a 250mcg dose, pull to 0.3 units (0 syringe ticks).
U-100 Syringe Representation
0.3 Units (0 Ticks)
Educational reference visual. Assumes standard U-100 insulin syringe where 1.0 mL volume = 100 units.
Titration & Dose Escalation Schedules
| Week | Daily Dose | Units (per injection) (mL) |
|---|---|---|
| Weeks 1–2 | 50 mg | 50 units (0.50 mL) |
| Weeks 3–8 | 100 mg | 100 units (1.0 mL) |
| Weeks 9–12 | 100 mg | 100 units (1.0 mL) |
Administration guidelines: Refer to guidelines | 2 mL Reconstitution
Research Supplies Quantity Planner
Scientific mathematical planning of syringes, bacteriostatic water and dry vials needed for extended research blocks using the 200 mg vial.
Peptide Vials (L-Carnitine, 200 mg each): Note: Each 200 mg vial reconstituted at 2.0 mL provides two 100 mg doses (or four 50 mg doses).
- check8 weeks (56 days @ 100 mg/day) ≈ 28 vials
- check12 weeks (84 days @ 100 mg/day) ≈ 42 vials
- check16 weeks (112 days @ 100 mg/day) ≈ 56 vials
Insulin Syringes (U-100, 1 mL capacity):
- checkPer week: 7 syringes (1/day)
- check8 weeks: 56 syringes
- check12 weeks: 84 syringes
- check16 weeks: 112 syringes
Bacteriostatic Water (10 mL bottles): Use 2.0 mL per vial for reconstitution.
- check8 weeks (28 vials): 56 mL → 6 × 10 mL bottles
- check12 weeks (42 vials): 84 mL → 9 × 10 mL bottles
- check16 weeks (56 vials): 112 mL → 12 × 10 mL bottles
Alcohol Swabs: One for vial stopper + one for injection site each day.
- checkPer week: 14 swabs (2/day)
- check8 weeks: 112 swabs → recommend 2 × 100-count boxes
- check12 weeks: 168 swabs → recommend 2 × 100-count boxes
- check16 weeks: 224 swabs → recommend 3 × 100-count boxes
Sharps Container: For safe disposal of used syringes and needles.
Mechanism of Action (MOA)
L-Carnitine ((R)-3-hydroxy-4-(trimethylammonio)butanoate) is a quaternary ammonium betaine synthesized endogenously in the liver, kidneys, and brain from the essential amino acids lysine and methionine, with iron, vitamin C, vitamin B6, and niacin as cofactors. Approximately 75 percent of body carnitine is obtained from dietary sources, with red meat and dairy as the primary contributors. The total body pool is approximately 20 grams, of which 98 percent is stored in skeletal and cardiac muscle. Carnitine is taken up into tissues by the high-affinity OCTN2 transporter (SLC22A5); loss-of-function mutations in OCTN2 cause primary systemic carnitine deficiency, a recessive metabolic disorder presenting in childhood with cardiomyopathy, hypotonia, and hypoketotic hypoglycemia [1]. The central physiological role of carnitine is to enable mitochondrial oxidation of long-chain fatty acids. Long-chain acyl-CoAs cannot cross the inner mitochondrial membrane directly. Instead, carnitine palmitoyltransferase 1 (CPT-1) on the outer mitochondrial membrane transfers the acyl group from CoA to carnitine, generating acylcarnitine. Acylcarnitine is shuttled across the inner mitochondrial membrane by the carnitine-acylcarnitine translocase (CACT, SLC25A20), and on the matrix side carnitine palmitoyltransferase 2 (CPT-2) transfers the acyl group back to CoA, releasing free carnitine for re-export and acyl-CoA for β-oxidation. CPT-1 is allosterically inhibited by malonyl-CoA, the first committed intermediate of fatty acid synthesis, providing reciprocal regulation between fatty acid synthesis and oxidation [2]. Beyond its fatty acid transport role, carnitine buffers the cellular acyl-CoA:CoA ratio, scavenges acyl groups under conditions of metabolic stress, modulates branched-chain amino acid catabolism, and participates in the export of poorly metabolized acyl groups via acylcarnitine excretion in urine. Carnitine also has indirect effects on glucose metabolism, oxidative stress, and gene expression that contribute to its broader therapeutic interest. FDA-approved indications for L-carnitine (brand name Carnitor) include primary carnitine deficiency and secondary deficiencies in patients on hemodialysis or receiving valproic acid. Standard oral doses for deficiency are 1000–3000 mg per day in divided doses in adults, with intravenous Carnitor (50 mg/kg per dialysis session) used in dialysis patients. Off-label uses include type 2 diabetes (where 1–2 g/day improves insulin sensitivity and reduces fasting glucose in meta-analyses), non-alcoholic fatty liver disease, peripheral artery disease (especially propionyl-L-carnitine 2 g/day for intermittent claudication), male infertility (2–3 g/day improves sperm motility and concentration), chronic fatigue (with acetyl-L-carnitine 1.5–3 g/day), and cardiovascular disease. A non-linear dose-response meta-analysis of 37 randomized trials documented that 2000 mg/day provides the maximum effect for weight loss and body composition modulation, with effects plateauing or diminishing at higher doses, likely because hepatic OCTN2 transporters saturate above this threshold [3]. Oral bioavailability ranges from 10 to 25 percent depending on formulation, dose, and dietary state, and exogenous L-carnitine is excreted unchanged in urine when intake exceeds tissue uptake capacity. Research intramuscular and subcutaneous L-carnitine injection at 200–500 mg per session is used in performance, recovery, and metabolic protocols on the rationale of bypassing the gut and saturating tissue carnitine stores faster than oral dosing; however, controlled comparative pharmacokinetic data in humans are limited [4].
Clinical Trial Efficacy Highlights
- starA non-linear dose-response meta-analysis of 37 randomized controlled trials published in 2020 (Clinical Nutrition) found that L-carnitine supplementation produced significant reductions in body weight and BMI compared with placebo, with the maximum effect achieved at approximately 2000 mg per day; higher doses did not produce additional benefit, likely reflecting saturation of hepatic OCTN2 carnitine transporters [3].
- starL-carnitine (Carnitor) received FDA approval in 1985 for primary carnitine deficiency and in 1999 for secondary deficiency in end-stage renal disease patients on hemodialysis; intravenous Carnitor at 10–20 mg/kg per dialysis session improves muscle weakness, anemia, and cardiac function in deficient dialysis populations [1].
- starPooled analyses of randomized trials in type 2 diabetes indicate that 1–2 g/day oral L-carnitine improves fasting glucose, HbA1c, and HOMA-IR insulin resistance index, with effects more pronounced in patients with established hyperglycemia and concurrent insulin resistance [4].
- starPropionyl-L-carnitine at 2 g/day has been evaluated in multiple randomized trials of intermittent claudication and peripheral artery disease, demonstrating improvements in walking distance and quality of life compared with placebo through enhanced skeletal muscle oxidative metabolism and endothelial function [4].
- starMultiple randomized trials in male infertility demonstrate that L-carnitine 2–3 g/day, often combined with acetyl-L-carnitine, improves sperm concentration, motility, and morphology over three to six months, supporting its inclusion in many male fertility supplementation regimens [2].
- starAcetyl-L-carnitine has been investigated in chronic fatigue syndrome, age-related cognitive decline, and diabetic peripheral neuropathy, with modest but consistent improvements in symptom scores at doses of 1.5–3 g/day in multiple controlled trials [2].
- starSafety data from decades of clinical use in carnitine deficiency, dialysis, and supplementation indicate excellent tolerability with mild gastrointestinal effects as the most common adverse events; concerns about TMAO production and cardiovascular risk from gut microbial metabolism of dietary carnitine have not been confirmed in supplementation trials of cardiac patients [1].
Side Effects & Tolerability Profile
Clinical subjects transiently report mild side effects. Slowly escalating the titration dose represents the single most effective intervention to limit side effects.
- warningOral L-carnitine commonly produces mild gastrointestinal effects including nausea, abdominal cramping, diarrhea, and a fishy body odor caused by gut microbial conversion to trimethylamine; the odor effect is dose-dependent and reversible.
- warningIntravenous and intramuscular L-carnitine can cause injection-site pain, transient hypotension, and rarely allergic reactions; sterile preparations and standard injection technique mitigate most local risks.
- warningCarnitine can lower seizure threshold in patients with epilepsy who are not on valproic acid, but conversely is used to mitigate valproate-induced hyperammonemia and hepatotoxicity in seizure populations.
- warningConcerns have been raised about gut microbial conversion of dietary L-carnitine to trimethylamine-N-oxide (TMAO), a metabolite associated with cardiovascular risk in epidemiologic studies, although supplementation trials have not demonstrated adverse cardiac outcomes.
- warningPharmacological doses can interact with thyroid hormone signaling, potentially reducing thyroid hormone receptor activity; supplementation should be approached cautiously in hypothyroid patients on replacement therapy.
- warningPatients on hemodialysis may experience changes in dialysis-related symptoms with carnitine repletion; muscle cramps, anemia, and dialysis hypotension generally improve.
- warningUse in pregnancy and lactation is generally considered safe at dietary or therapeutic doses, since carnitine is essential during pregnancy, but high-dose supplementation should be discussed with a clinician.
Subcutaneous Injection Technique
Most research peptides require subcutaneous injection into fatty tissue. Never inject directly into a blood vessel or deep muscle tissue unless clinically detailed.
1. Site Selection
Common locations include the abdomen (2 inches from navel), outer upper arms, or thighs.
2. Sanitization
Thoroughly clean the selected site, stopper and vial top using 70% isopropyl alcohol prep swabs.
3. Angle & Push
Pinch the skin and insert the needle at a 45 to 90-degree angle. Depress plunger smoothly.
4. Site Rotation
Rotate injection sites continuously to avoid lipodystrophy or tissue scarring.
Frequently Asked Questions
What is the typical L-carnitine dosage?expand_more
Oral L-carnitine for general health and weight management uses 1000–2000 mg/day in divided doses, with 2000 mg/day identified as the dose-response maximum in meta-analysis. Carnitine deficiency uses 1000–3000 mg/day. Research intramuscular or subcutaneous injection is 200–500 mg per session.
How is L-carnitine administered?expand_more
L-carnitine is most commonly administered orally as L-carnitine tartrate, acetyl-L-carnitine, or propionyl-L-carnitine, taken with meals to improve tolerability. Intravenous Carnitor is FDA-approved for dialysis patients. Research IM/SC injections use lower doses to bypass first-pass metabolism.
Can L-carnitine be combined with other compounds?expand_more
L-carnitine is frequently combined with CoQ10, alpha-lipoic acid, B vitamins, and creatine in performance and metabolic protocols. In male infertility, it is paired with acetyl-L-carnitine. Drug interactions are limited; valproic acid depletes carnitine, supporting concurrent supplementation.
What are the side effects of L-carnitine?expand_more
Oral L-carnitine commonly causes mild gastrointestinal effects (nausea, cramping, diarrhea) and a fishy body odor from microbial conversion to trimethylamine. IV/IM use can cause injection-site pain and rare hypotension. Long-term cardiovascular safety remains debated due to TMAO concerns.
Is L-carnitine FDA approved?expand_more
Yes. L-carnitine (brand name Carnitor) is FDA-approved as an orphan drug for primary carnitine deficiency and for secondary deficiency in end-stage renal disease patients on dialysis. L-carnitine is also available as a dietary supplement; non-deficiency uses are off-label.
Academic References & Study Citations
Longo N, Frigeni M, Pasquali M. Carnitine transport and fatty acid oxidation. Biochim Biophys Acta. 2016;1863(10):2422-2435. View Scientific Paper →
Pekala J, Patkowska-Sokoła B, Bodkowski R, et al. L-carnitine—metabolic functions and meaning in humans life. Curr Drug Metab. 2011;12(7):667-678. View Scientific Paper →
Talenezhad N, Mohammadi M, Ramezani-Jolfaie N, Mozaffari-Khosravi H, Salehi-Abargouei A. Effects of L-carnitine supplementation on weight loss and body composition: a systematic review and meta-analysis of 37 randomized controlled clinical trials with dose-response analysis. Clin Nutr ESPEN. 2020;37:9-23. View Scientific Paper →
Brass EP. Carnitine and sports medicine: use or abuse? Ann N Y Acad Sci. 2004;1033:67-78. View Scientific Paper →
Lheureux PE, Penaloza A, Zahir S, Gris M. Science review: carnitine in the treatment of valproic acid-induced toxicity—what is the evidence? Crit Care. 2005;9(5):431-440. View Scientific Paper →
Hiatt WR. Carnitine and peripheral arterial disease. Ann N Y Acad Sci. 2004;1033:92-98. View Scientific Paper →
Lenzi A, Lombardo F, Sgrò P, et al. Use of carnitine therapy in selected cases of male factor infertility: a double-blind crossover trial. Fertil Steril. 2003;79(2):292-300. View Scientific Paper →
Koeth RA, Wang Z, Levison BS, et al. Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med. 2013;19(5):576-585. View Scientific Paper →
Vermeulen RC, Scholte HR. Exploratory open label, randomized study of acetyl- and propionylcarnitine in chronic fatigue syndrome. Psychosom Med. 2004;66(2):276-282. View Scientific Paper →