These are statements from the prescribing information for cyanocobalamin injection, one repackager's label of an approved product. They apply to that product and to the populations the label names. No source used in this guide gives a schedule for any compounded vial.
Route and the pernicious anemia wording
The label states to avoid using the intravenous route, because use of this product intravenously will result in almost all of the vitamin being lost in the urine.
For pernicious anemia, the label states that parenteral vitamin B12 is the recommended treatment and will be required for the remainder of the patient's life, that the oral form is not dependable, and that a dose of 100 mcg daily for 6 or 7 days should be administered by intramuscular or deep subcutaneous injection. It also states that patients with pernicious anemia should be informed that they will require monthly injections of vitamin B12 for the remainder of their lives.
That is the label's wording for patients with pernicious anemia. It is not a schedule for anyone else.
Normal absorption and diet statements
For patients with normal intestinal absorption, the label says that where the oral route is not deemed adequate, initial treatment similar to that for patients with pernicious anemia may be indicated depending on the severity of the deficiency, and that chronic treatment should be with an oral B12 preparation.
On diet, the label states that a vegetarian diet which contains no animal products (including milk products or eggs) does not supply any vitamin B12, and that patients following such a diet should be advised to take oral vitamin B12 regularly. That statement is about a diet with no animal products. It does not describe other diets.
Tests, potassium and the allergy warning
The label states that hematocrit, reticulocyte count, vitamin B12, folate and iron levels should be obtained prior to treatment. It also states that during the initial treatment of patients with pernicious anemia, serum potassium must be observed closely the first 48 hours and potassium replaced if necessary.
The label warns that anaphylactic shock and death have been reported after parenteral vitamin B12 administration, and it recommends an intradermal test dose before the product is administered to patients suspected of being sensitive to this drug. The wording quoted here gives no frequency. Separately, an FDA page encourages people with an adverse reaction to a compounded medication to report it to their health care professional and directly to FDA, and says to ask a health care professional if unsure whether a medication is compounded.
Interactions the label lists
The label says that persons taking most antibiotics, methotrexate and pyrimethamine invalidate folic acid and vitamin B12 diagnostic blood assays. It also says that colchicine, para-aminosalicylic acid and heavy alcohol intake for longer than 2 weeks may produce malabsorption of vitamin B12. The first statement concerns blood test results. The second concerns absorption.
Approved products and compounded drugs
The Drugs@FDA record for ANDA 080515 lists a product named CYANOCOBALAMIN with active ingredient CYANOCOBALAMIN, strength 1MG/ML, dosage form and route INJECTABLE;INJECTION, and marketing status Prescription. The record lists product details. It does not show which repackaged label is cited here.
The FDA states that compounded drugs are not FDA-approved, which means that FDA does not verify the safety, effectiveness or quality of compounded drugs before they are marketed. The label statements above are for the approved product and its labeled populations.
What this does not tell you
This guide repeats label wording. It does not give a dose, route or schedule for any person, and it does not say whether to start, stop or change anything. The pernicious anemia wording is for patients with that condition and does not carry over to people without it. No source used here gives a schedule for a compounded vial. Whether a product, route or schedule fits a person is for a licensed provider to decide.