2. • This medication is used to treat people with
serious kidney disease who have high levels of a
parathyroid hormone(PTH). High PTH levels affect
the balance of other minerals in body (calcium and
phosphorus) and may result in weak
bones. Doxercalciferol is a man-made form of vitamin
D. It works by decreasing PTH levels and increasing
calcium /phosphorus levels in the body.
3. • The U.S. District Court for the District of
Delaware found in favour of Genzyme and
against ANDA applicants Roxane in the
paragraph IV litigation concerning HECTOROL
(doxercalciferol).
• The court ruled that defendants' ANDA
products would induce infringement of claim
7 of U.S. Patent No. 5,602,116; and that claim
7 is not invalid as "inoperative" or obvious.
4. Claim 7 of the '116 patent is directed to:
• A method for lowering or maintaining lowered
serum parathyroid hormone [PTH] in patients
suffering from hyperparathyroidism secondary
to end stage renal disease, comprising:
administering to patients an effective amount
of [doxercalciferol] to lower and maintain
lowered serum parathyroid hormone levels.
5. After a hearing,
• The court construed the term "effective
amount of doxercalciferol to lower and
maintain lowered serum parathyroid hormone
levels" to mean "an amount of doxercalciferol
sufficient to lower and maintain lowered
blood concentrations of PTH with a lower
incidence of hypercalcemia than would result
from using calcitriol or alfacalcidol to achieve
the same level of PTH suppression."
6. • After concluding that claim 7 would be
directly infringed by the defendants' ANDA
products (a predicate to finding inducement of
infringement), the court addressed whether
the defendants have the required intent to
induce infringement. The key issue here was
whether the defendants intend to induce
infringement of claim 7 notwithstanding that
their proposed labeling says nothing about the
incidence of hypercalcemia .In this case, all
defendants filed ANDAs with the FDA seeking
approval to market a doxercalciferol.
