L-Carnitine 500

L-Carnitine 500mg/ml Injectable by Dragon Pharma

L-Carnitine 500 is Dragon Pharma's injectable formulation of L-Carnitine at 500mg/ml in a 10ml aqueous vial — providing near-complete bioavailability versus the 14-18% typically achieved through oral supplementation. L-Carnitine is a quaternary ammonium compound synthesised from lysine and methionine, essential for the transport of long-chain fatty acids across the inner mitochondrial membrane for beta-oxidation. In AAS contexts, L-Carnitine has an additional documented role: androgen receptor upregulation in muscle tissue.

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Why Injectable vs Oral — The Bioavailability Gap

The case for injectable L-Carnitine over oral supplementation rests on a significant and specific bioavailability difference:

• Oral L-Carnitine absorption is limited by active intestinal transport systems that become saturated at moderate doses — bioavailability is typically 14-18% from supplement form and 54-72% from food sources (where L-Carnitine is bound to proteins and absorbed differently)
• A 2g oral L-Carnitine supplement delivers approximately 280-360mg to systemic circulation. The same 2g administered intravenously or via intramuscular/subcutaneous injection delivers close to 100% systemically
• At 500mg/ml, a single 2ml injection of Dragon Pharma L-Carnitine delivers 1,000mg with near-complete bioavailability — equivalent to approximately 5,500-7,000mg of oral L-Carnitine supplement in terms of what reaches the bloodstream
• This bioavailability advantage is particularly relevant for the androgen receptor upregulation application (below), where plasma L-Carnitine concentrations — not gut absorption — determine the effect

How L-Carnitine Works — The CPT Shuttle Mechanism

L-Carnitine's primary metabolic function is a specific and elegant transport mechanism that most competitor content reduces to "moves fat to mitochondria":

• Long-chain fatty acids (the primary fat fuel for aerobic metabolism) cannot cross the inner mitochondrial membrane directly — they require a specific transport system
• L-Carnitine acts as the shuttle carrier in the carnitine palmitoyltransferase (CPT) system: CPT1 on the outer mitochondrial membrane conjugates L-Carnitine to the fatty acid (forming acylcarnitine); the acylcarnitine complex crosses the inner mitochondrial membrane via a translocase; CPT2 on the inner membrane cleaves the complex, releasing the fatty acid inside the mitochondrial matrix where beta-oxidation occurs
• Without sufficient L-Carnitine, this shuttle is rate-limiting — fatty acids accumulate in the cytoplasm rather than entering the mitochondria for oxidation
• Providing supraphysiological L-Carnitine ensures the CPT shuttle is never rate-limiting — maximising the rate at which fatty acids can be transported into mitochondria and oxidised for energy
• This is particularly relevant during fasted states and aerobic exercise when fatty acid oxidation is the primary energy source — L-Carnitine availability becomes the critical bottleneck

L-Carnitine and Androgen Receptor Upregulation — The AAS-Specific Benefit

This is one of the most clinically interesting and least-known aspects of L-Carnitine in an AAS context:

• A series of studies by Kraemer et al. (published in Journal of Strength and Conditioning Research, 2006 and subsequently) demonstrated that L-Carnitine L-Tartrate supplementation significantly upregulated androgen receptor content in muscle tissue — specifically in fast-twitch muscle fibres
• The mechanism: L-Carnitine is involved in the recovery of androgen receptors following exercise-induced downregulation. Post-exercise, androgen receptor content in muscle declines temporarily as part of the exercise stress response. L-Carnitine supplementation was shown to attenuate this post-exercise downregulation, maintaining higher androgen receptor density during the recovery period
• The practical implication for AAS users: more androgen receptors in muscle during the recovery period means more receptor availability for the exogenous androgens circulating from the cycle — potentially enhancing the anabolic signalling from a given AAS dose
• This effect was observed at plasma L-Carnitine concentrations achievable by injectable supplementation but difficult to achieve reliably with oral supplementation given the bioavailability gap

Effects and Benefits

• Enhanced fatty acid transport into mitochondria via CPT shuttle saturation — maximises fat oxidation during fasted training and aerobic work
• Androgen receptor upregulation in muscle tissue — maintains receptor density during post-exercise recovery, potentially enhancing AAS anabolic signalling
• Reduced exercise-induced muscle damage markers in some studies — potentially faster recovery between sessions
• No hormonal suppression — does not affect testosterone, HPG axis or require PCT
• Near-complete bioavailability versus 14-18% oral absorption

Dosage and Administration

At 500mg/ml, a 2ml injection delivers 1,000mg; a 4ml injection delivers 2,000mg. The 10ml vial at 2,000mg/day provides 2.5 days at maximum dose — at the 1,000mg/day protocol, the 10ml vial provides 5 days. Injection can be intramuscular or subcutaneous — intramuscular is more commonly used for L-Carnitine injection due to faster absorption and lower injection site reaction risk at high volumes. Rotating injection sites is essential at daily dosing.