Expanding Access to High-Quality Compounded Medications
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Carnitine (L) Injection is a sterile compounded solution containing Levocarnitine-the biologically active L-isomer of carnitine-at a concentration of 500 mg/mL, dispensed in a 30 mL vial.
Levocarnitine is an amino-acid derivative essential for mitochondrial fatty-acid transport, and this injectable formulation is used to treat or prevent clinically significant carnitine deficiency in conditions such as primary systemic carnitine deficiency, certain inborn errors of metabolism, and end-stage renal disease on dialysis.
By restoring normal carnitine levels, therapy aims to improve energy production, muscle function, and cardiac performance in patients unable to maintain adequate stores through diet or oral supplements.
Dosing is individualized to body weight, severity of deficiency, and clinical context.
In hereditary or acquired metabolic defects, an initial intravenous bolus of 50 mg/kg may be administered over two to three minutes, followed by maintenance doses of 50 mg/kg every six hours or continuous infusion to achieve a total daily exposure of up to 300 mg/kg in critical illness.
Hemodialysis patients commonly receive 10-20 mg/kg intravenously at the end of each dialysis session, with trough free carnitine concentrations guiding subsequent adjustments.
Compounded vials containing 500 mg/mL should be diluted to 2-8 mg/mL in isotonic saline for infusion; intramuscular use is limited to small, divided volumes.
Therapy duration varies from acute correction in metabolic crises to lifelong supplementation in primary systemic deficiency.
Missed doses should not be doubled; instead, resume the prescribed schedule and consult the clinician for guidance.
Levocarnitine exerts its therapeutic effect by serving as a carrier molecule that transports activated long-chain fatty acids across the inner mitochondrial membrane. It forms acyl-carnitine esters with acyl-CoA derivatives, enabling entry into the mitochondrial matrix where β-oxidation generates acetyl-CoA and ultimately ATP.
This shuttle ensures efficient oxidation of fatty acids in energy-dependent tissues such as skeletal muscle and myocardium. In addition, levocarnitine buffers excess intramitochondrial acyl-CoA, regenerating free coenzyme A and potentially preventing inhibition of critical metabolic enzymes.
By facilitating removal of potentially toxic acyl groups and stabilizing cellular membranes, levocarnitine may support metabolic flexibility and protects against accumulation of organic acids.
Replenishing systemic stores may restore normal oxidative capacity and improves metabolic homeostasis in deficient states.
Levocarnitine injection carries no absolute contraindications in FDA labeling; however, administration is inadvisable in any patient with a known hypersensitivity to levocarnitine or formulation components.
Caution is recommended in individuals with seizure disorders, as increased frequency or severity of seizures has been reported during therapy.
Accumulation may occur in patients with severe renal impairment who are not receiving dialysis, necessitating careful monitoring.
Only the L-isomer should be used clinically, because exposure to the racemic D, L-carnitine has produced reversible myasthenia in uremic patients.
Clinically important interactions with levocarnitine are uncommon, but two deserve attention.
Concomitant use with coumarin anticoagulants such as warfarin has been associated with elevations in the international normalized ratio, requiring closer INR surveillance and potential dose adjustment.
High-dose levocarnitine can also antagonize the intracellular actions of thyroxine and triiodothyronine by limiting their nuclear uptake; patients receiving thyroid-hormone replacement or those with thyroid dysfunction should be monitored for changes in symptom control.
Other routinely prescribed drugs, vitamins, and enteral or parenteral nutrition products have not demonstrated significant pharmacokinetic or pharmacodynamic interference.
The most frequently reported adverse effects include transient gastrointestinal discomfort-nausea, vomiting, abdominal cramps, or diarrhea-particularly when large doses are delivered rapidly.
A distinctive fish-like odor of breath, sweat, or urine may emerge as trimethylamine metabolites are excreted; although benign, it can be socially bothersome.
Local pain, erythema, or phlebitis may develop at intravenous or intramuscular injection sites, mitigated by slow administration and site rotation.
Rare but serious events encompass provocation or exacerbation of seizures in susceptible individuals and hypersensitivity reactions ranging from urticaria to anaphylaxis.
Overall, events are usually mild and reversible upon dose adjustment or discontinuation.
Animal reproduction studies have not demonstrated fetal harm with levocarnitine, and the drug is classified as Pregnancy Category B.
Because adequate, well-controlled studies in pregnant individuals are lacking, use should be limited to circumstances in which the potential maternal benefit clearly outweighs theoretical fetal risk-such as treatment of documented systemic carnitine deficiency.
Levocarnitine is a normal constituent of human milk, and supplemental doses may modestly increase breast-milk concentrations; no adverse outcomes have been attributed to nursing infants, yet unnecessary exposure should be avoided.
Prescribers should base decisions on clinical necessity and monitor both mother and infant when use during lactation is unavoidable.
Carnitine (L) Injection should be stored at controlled room temperature-20 to 25 °C (68 to 77 °F)-and protected from light in its original carton.
Do not freeze or expose to excessive heat.
Visual inspection for particulate matter or discoloration is required before administration; compromised vials should be discarded according to local disposal regulations.
