Adults

Typically 1 mL (50 mg total B-complex or specific component) administered intramuscularly once daily or as prescribed by a physician, depending on the severity of deficiency and clinical response.

Elderly

No specific dose adjustment is generally required for elderly patients; adult dosage is usually appropriate unless significant renal impairment is present.

Renal_impairment

Generally, no dose adjustment is necessary for water-soluble vitamins in mild to moderate renal impairment. For severe renal impairment, consult a physician, though excess vitamins are typically excreted.

Onset

Therapeutic effects may begin within minutes to hours, depending on the specific vitamin and deficiency severity.

Excretion

Water-soluble B vitamins and their metabolites are primarily excreted renally via the urine. Excess amounts are readily eliminated.

Half life

Varies by individual B vitamin component: Thiamine (9-18 days), Riboflavin (2-3 hours), Pyridoxine (15-20 days), Niacinamide (20-45 minutes), Cyanocobalamin (6 days to several months, due to storage).

Absorption

Rapidly absorbed into the systemic circulation following intramuscular administration.

Metabolism

Primarily metabolized in the liver, with varying pathways for each B vitamin.

Levodopa

Pyridoxine (Vitamin B6) may reverse the antiparkinsonian effects of levodopa (without carbidopa) by increasing its peripheral metabolism.

Phenytoin and Phenobarbital

High doses of pyridoxine (Vitamin B6) may reduce the serum levels and therapeutic effects of phenytoin and phenobarbital.

Isoniazid, Penicillamine, Oral Contraceptives

These medications can increase the requirement for pyridoxine.