SIDE EFFECTS
The incidence of gastrointestinal complaints (diarrhea,
nausea) is the same for Didronel at 5 mg/kg/day as for
placebo, about 1 patient in 15. At 10 to 20 mg/kg/day
the incidence may increase to 2 or 3 in 10. These complaints
are often alleviated by dividing the total daily dose.
Paget’s Disease
In Paget’s patients, increased or recurrent bone
pain at pagetic sites, and/or the onset of pain at previously
asymptomatic sites has been reported. At 5 mg/kg/day about
1 patient in 10 (versus 1 in 15 in the placebo group)
report these phenomena. At higher doses the incidence
rises to about 2 in 10. When therapy continues, pain resolves
in some patients but persists in others.
Heterotopic Ossification
No specific adverse reactions.
Worldwide Postmarketing Experience
The worldwide postmarketing experience for etidronate
disodium reflects its use in the following approved indications:
Paget’s disease, heterotopic ossification, and hypercalcemia
of malignancy. It also reflects the use of etidronate
disodium for osteoporosis where approved in countries
outside the US. Other adverse events that have been reported
and were thought to be possibly related to etidronate
disodium include the following: alopecia; arthropathies,
including arthralgia and arthritis; bone fracture; esophagitis;
glossitis: hypersensitivity reactions, including angioedema,
follicular eruption, maculopapular rash, pruritus, a single
case of Stevens-Johnson syndrome, and urticaria; osteomalacia;
neuropsychiatric events, including amnesia, confusion,
depression, and hallucination; and paresthesias.
In patients receiving etidronate disodium, there have
been rare reports of agranulocytosis, pancytopenia, and
a report of leukopenia with recurrence on rechallenge.
In addition, there have been rare reports of exacerbation
of asthma. Exacerbation of existing peptic ulcer disease
has been reported in a few patients. In one patient, perforation
also occurred.
In osteoporosis clinical trials, headache, gastritis,
leg cramps, and arthralgia occurred at a significantly
greater incidence in patients who received etidronate
as compared with those who received placebo.
DRUG INTERACTIONS
There have been isolated reports of patients experiencing
increases in their prothrombin times when etidronate was
added to warfarin therapy. The majority of these reports
concerned variable elevations in prothrombin times without
clinically significant sequelae. Although the relevance
of these reports and any mechanism of coagulation alterations
is unclear, patients on warfarin should have their prothrombin
time monitored.
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