Calcium bioavailability supplements

When administered with ranitidine, alendronate bioavailability is increased. When calcium supplements or antacids are administered with risedronate or alendronate, absorption of the bisphosphonates is decreased, hi addition, risedronate absorption is inhibited when the drug is administered with magnesium and aluminum. There is an increased risk of gastrointestinal... 

High levels of dietary zinc were associated with marked decreases in bone calcium deposition and in the apparent retention of calcium in male weanling albino rats. Marked increases in fecal calcium levels were also observed in the zinc-fed rats. Excessive dietary zinc was associated with a shifting of phosphorus excretion from the urine to the feces. This resulted in an increase in fecal phosphorus and provided an environmental condition which would increase the possibility of the formation of insoluble calcium phosphate salts and a subsequent decrease in calcium bioavailability. The adverse effect of high dietary zinc on calcium status in young rats could be alleviated and/or reversed with calcium supplements. 

Bisphosphonates such as etidronate are often coprescribed with calcium supplements in the treatment of osteoporosis. If these are ingested concomitantly, the bioavailability of both is significantly reduced with the possibility of therapeutic failure. This may be avoided by allowing a sufficiently long dosage interval a possible approach is to give etidronate for 2 weeks and calcium supplements for 10 weeks in a 12-week period. 

Stass H, et al. Effect of calcium supplements on the oral bioavailability of moxifloxacin in healthy male volunteers. Clin. Pharmacohinet., 2001, 40 (Suppl. 1), 27-32. 

We would have to question the validity of the use of dietary calcium levels of up to 1.75% calcium in rat studies to study zinc bioavailability. These levels would never be approached in human diets without use of excessive calcium supplementation. 

The manufacturers note that food, milk, dairy products, and calcium supplements reduce the bioavailability of strontium ranelate by about 60 to 70%, when compared with administration 3 hours after a med. This is because divalent cations such as calcium form complexes with strontium ranelate so preventing its absorption. Therefore, strontium ranelate should not be taken within 2 hours of eating, or presumably within 2 hours of any calcium compound. The manufacturer recommends that strontium ranelate should be taken at bedtime, at least 2 hours after eating. ... 

A major concern associated with clinical trials designed to evaluate the health effects of micronutrients (as well as other dietary supplements and drugs) is that participants might take additional micronutrient supplements, which could influence trial outcomes. In the Prostate Cancer Prevention Trial (PCPT) of the drug finasteride, for example, almost half of the participants reported using a multivitamin/ mineral supplement, about one-third used single supplements of either vitamin C or E, and one in five used calcium supplements. Very little evidence is available on how individual micronutrient substances may interact with one another to influence health outcomes. For minerals, particularly, supplementation with one mineral may compromise the bioavailability of another. Also, much remains to be learned about how individual genetic susceptibilities may influence the health-related effects of micronutrient... 

The data presented in this paper indicate that excess levels (0.75%) of dietary zinc result in decreases in the bioavailability of calcium and phosphorus in rats and interfere with normal bone mineralization. High dietary levels of calcium or zinc appeared to cause a shift in the excretion of phosphorus from the urine to the feces, while the presence of extra phosphorus tended to keep the pathway of phosphorus excretion via the urine. The presence of large amounts of phosphorus in the Intestinal tract due to high intakes of zinc would increase the possibility of the formation of insoluble phosphate salts with various cations, including calcium, which may be present. A shift in phosphorus excretion from the feces to the urine, however, could result in an environmental condition within the system which would tend to increase the bioavailability of cations to the animal. The adverse effect of zinc toxicity on calcium and phosphorus status of young rats could be alleviated with calcium and/or phosphorus supplements. 

In addition, gelatin peptides have shown to accelerate absorption of dietary calcium in animal models increasing calcium bioavailability (Kim et al., 1998). Jung et al. (2006) reported that fish bone peptides (FBP) could inhibit the formation of insoluble Ca salts in neutral pFI. During the experimental period, Ca retention was increased and loss of bone mineral was decreased by FBP II supplementation in ovariectomized rats. The levels of femoral total Ca, bone mineral density, and strength were also significantly increased by the FBP diet to levels similar to those of the casein phosphopeptide diet group. 

If the product is the subject of an NDA or an ANDA, a supplemental NDA must be filed [21CFR314.70(b)(2)]. It must be shown that the change does not affect the bioavailability of the active ingredient(s). CMC information for drug substances used in over-the-counter (OTC) products covered by an OTC monograph (e.g., calcium carbonate) are not reviewed. Therefore, a DMF need not be filed. The fact that there are existing DMFs for calcium carbonate does not mean that they are reviewed. CMC information for OTC products not covered by an OTC monograph (e.g., famotidine) does need to be reviewed. A DMF is an appropriate mechanism to submit such information. 

Table I. Calcium (Ca) Supplementation and Manganese (Mn) Bioavailability in Human Adults...

Administered as a once-daily, 20-pg SC injection in the thigh or abdominal wall, teriparatide is a clear, colorless liquid that is available as a 750 pg/3 ml, prefilled, disposable pen that requires refrigeration. Concurrent calcium (1,000 mg) and vitamin D (400 lU) supplementation is recommended. Treatment for longer than 2 years is not recommended. Teriparatide is rapidly absorbed, demonstrates 95% bioavailability, and is quickly eliminated via both hepatic and extrahepatic routes. The half life is 1 hour when administered SC. Metabolic studies have not been performed on teriparatide however, the entire PTH preprohormone has been shown to undergo enzyme-mediated transformations in the liver. Dizziness and leg cramps are the most commonly reported adverse side effects. 

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