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CaloMist Nasal Spray

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CaloMist Nasal Spray

CLINICAL PHARMACOLOGY

Mechanism of Action

Vitamin B12 is essential for growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. Rapidly dividing cells (e.g., epithelial cells, bone marrow, myeloid cells) have the greatest requirement for vitamin B12. In tissues, vitamin B12 is essential for the conversion of methylmalonate to succinate and for the synthesis of methionine from homocysteine. In the absence of vitamin B12, tetrahydrofolate cannot be regenerated from 5-methyl tetrahydrofolate, and functional folate deficiency occurs. Vitamin B12 also may be involved in sulfhydryl-activated enzyme systems associated with fat and carbohydrate metabolism and protein synthesis.

Pharmacodynamics

In 24 vitamin B12 deficient patients who were stabilized on intramuscular (IM) vitamin B12 therapy, once daily intranasal dosing with CaloMist Nasal Spray for 8 weeks resulted in serum vitamin B12 concentrations that were within the target range (>200 ng/L) and slightly higher than those seen 2 to 4 weeks after administration of IM vitamin B12 (see Figure 1 - average mean increase from Visit 1 to Visits 3-6 = 45 ng/L). Twenty-three of these 24 patients received 50 mcg of CaloMist Nasal Spray daily for the duration of the trial; the remaining patient required doubling of the CaloMist Nasal Spray dose from 50 mcg to 100 mcg daily during the last week of the study because of declining vitamin B12 concentrations. One of the 25 patients dosed with CaloMist Nasal Spray was excluded from the efficacy analyses because a diagnosis of vitamin B12 deficiency could not be confirmed.

Figure 1 : Mean Vitamin B12 Serum Levels Over 8 Weeks of Intranasal (IN) Vitamin B12 Dosing in 24 Subjects Stabilized on Intramuscular (IM) Vitamin B12

Mean Vitamin B12 Serum Levels Over 8 Weeks of Intranasal (IN) Vitamin B12 Dosing in 24 Subjects Stabilized on Intramuscular (IM) Vitamin B12  - illustration

Notes:

- Weeks -2 to -4 correspond to 2 to 4 weeks post last IM injection
- CaloMist Nasal Spray was initiated at Week 0.
- Figure shows mean vitamin B12 serum levels with 95% confidence intervals.

Pharmacokinetics Distribution

In the blood, vitamin BI2 is bound to transcobalamin II (a specific B-globulin carrier protein) and is distributed to tissues and stored primarily in the liver and bone marrow.

Elimination

About 3-8 mcg of vitamin B12 is secreted into the gastrointestinal tract daily via the bile. In subjects with sufficient intrinsic factor, all but about 1 mcg is reabsorbed. When vitamin B12 is administered in doses that saturate the binding capacity of plasma proteins and the liver, the unbound vitamin B12 is rapidly eliminated in the urine. Retention of vitamin B12 in the body is dose-dependent.

Last reviewed on RxList: 8/16/2007
This monograph has been modified to include the generic and brand name in many instances.

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