- Single-dose administration
Mecobalamin was administered intramuscularly or intravenously to 12 healthy adult male volunteers at a single dose of 500 mcg. The time to reach peak serum total vitamin B12 (abbreviated to B12) concentration (tmax) was 0.9 hr after intramuscular administration and immediately to 3 min. after intravenous administration, and the increment (except endogenous serum total B12) in peak serum total vitamin B12 concentration (ΔCmax) was 22.4 ng/mL after intramuscular administration and 85.0 ng/mL after intravenous administration.
The area under the serum total B12 concentration-time curve (ΔAUC) calculated by increment of the actual values at 144 hr. after administration was 204.1 ng•hr/mL after intramuscular administration and 358.6 ng•hr/mL after intravenous administration.
On the other hand, the rate of binding saturation showed a similar increase in both groups of subjects for 144 hr. after administration.
Serum total vitamin B12 concentration after single administration of Mecobalamin (METHYCOBAL®) Injection 500 mcg
Pharmacokinetic parameters after a single dose administration of Mecobalamin (METHYCOBAL®) Injection 500 mcg
| Tmax (hr) | ΔCmax (ng/mL) | ΔAUC0144 (ng•hr/mL) | T1/2 (hr) | |
| I.V | 0-3 min | 85.0 ± 8.9 | 358.6 ± 34.4 | 27.1 |
| I.M | 0.9 ± 0.1 | 22.4 ± 1.1 | 204.1 ± 12.9 | 29 |
| Mean ± S.E., n=12 | ||||
- Repeated-dose administration
Mecobalamin was administered intravenously to 6 healthy adult male volunteers at a single dose of 500 mcg daily for 10 consecutive days. Serum total B12 concentration determined before each administration increased from day to day. After 2 days of administration, the serum total B12 concentration was 5.3±1.8 ng/mL, about 1.4 times the 24 hr value (3.9±1 2 ng/mL) after administration. At 3 days of administration it had increased to 6.8±1.5 ng/mL, about 1.7 times the 24 hr value, and this concentration was maintained until the last dosing.
