Patients taking the anemia drug Eprex shouldn't stop their taking mediation without consulting their doctors, despite concerns over the drug, says Health Canada.

The announcement comes after the Puerto Rican factory where the Johnson & Johnson drug is made came under investigation for unsafe manufacturing processes.

The drug has also recently been linked to 141 cases in Canada and Europe of a rare condition called pure red cell aplasia, also known as PRCA.

Patients with the condition experience unexplained drops in red blood cell counts, which leaves them severely ill and dependent on transfusions.

Adding to the confusion for patients on Eprex was Friday's announcement that U.S. authorities are investigating accusations that records were falsified at Johnson & Johnson's Manati factory, where the drug is made.

A former employee of the Puerto Rico facility is suing Johnson & Johnson saying he was unjustly fired for refusing to falsify documents before an inspection.

Aplasia cases linked to injections under skin

Eprex is used to promote red blood cell production in patients whose kidneys have failed or have undergone chemotherapy, as well as some patients with HIV and those receiving blood donations.

On Monday, Health Canada spokeswoman Tara Madigan said patients should not discontinue their medication without seeing their doctors.

Health Canada said the cases of PRCA so far involved only kidney patients who received the drug through injections under the skin.

The subcutaneous injection is a new method of delivering the drug, used only since the mid-1990s, and some believe this method may be the reason behind the recent cases of PRCA.

The drug's Canadian distributor, Janssen-Ortho, suggested in a July 4 safety update that injecting Eprex under the skin may increase the chance that the body would produce antibodies against the drug.

This could affect the effectiveness of Eprex and perhaps cause the PRCA cases seen in Europe and Canada.

Janssen-Ortho, Health Canada and Johnson & Johnson all said doctors should administer the drug intravenously whenever possible.

Health Canada said kidney patients on Eprex should seek medication attention immediately if they feel fatigue or a sudden shortness of breath, both symptoms of PRCA.