Prilosec (Omeprazole) Plus Calcium Carbonate Decreases Calcium Absorption In Elderly Women

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Prilosec (Omeprazole) Plus Calcium Carbonate Decreases Calcium Absorption In

Elderly Women

By Anne son

Special to DG News

WASHINGTON, DC -- May 15, 2002 -- The concomitant use of Prilosec

(omeprazole) with calcium carbonate and no food decreases calcium absorption

in most elderly women.

" Of our 18 patients, 16 had decreased fractional calcium absorption and two

subjects had increased fractional calcium absorption on omeprazole, " said

Dr. Beth O'Connell, PharmD, from University of Minnesota, in

Minneapolis, Minnesota, United States. She reported findings here Friday at

the annual scientific meeting of the American Geriatrics Society in

Washington, DC.

Calcium carbonate needs an acidic medium for disintegration and digestion.

To determine if acid suppression induced by omeprazole would result in

decreased calcium absorption, Dr. O'Connell and colleagues conducted a

placebo-controlled, double-blind crossover study in 18 women aged 65-89

(76±6.5 years).

In the first arm of the study, subjects were randomly selected to receive

seven days of the proton pump inhibitor omeprazole or placebo. Beginning one

week prior to study day 1, subjects took vitamin D 400 IU/day throughout the

study period. Calcium carbonate supplements were held one week before each

study day.

On study day 1, subjects ingested radioactively labeled calcium carbonate

(45-CaCO3) 1.25 gm and the study drug. Blood samples were drawn prior to

45-CaCO3 and five hours later. Subjects fasted from the previous night until

the five-hour sample.

Calcium concentrations were determined by atomic absorption

spectrophotometry. Fractional calcium absorption was calculated based on

serum concentrations of radioactively labeled calcium carbonate, height, and

weight.

In the second arm of the study, the procedure was repeated with the other

drug after a washout period lasting at least three weeks.

At the end of the study period, Dr. O'Connell and her colleagues found that

the mean fractional calcium absorption decreased from 9.1±5.1 percent on

placebo to 3.5±3.9 percent on omeprazole (p=0.003). Sixteen women achieved a

decrease in fractional calcium absorption on omeprazole, while two women had

increases in fractional calcium absorption on concomitant omeprazole and

calcium carbonate.

The mean difference in fractional calcium absorption was -5.5±-6.9 percent

and ranged from -18.6 percent to 12.1 percent.

Though no period effect was seen, age did seem to play a role in fractional

calcium absorption, Dr. O'Connell noted. " Age correlated with fractional

calcium absorption while on omeprazole, but not for placebo or the

difference, " she said.