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Review of data indicating life-threatening heart abnormality underway

The U.S. Food and Drug Administration today announced preliminary data suggesting that Invirase (saquinavir) in combination with Norvir (ritonavir) may have potentially important adverse effects on the heart.

When used together, the drugs may cause prolongation of the QT and PR intervals on an electrocardiogram. Prolongation of the QT interval may lead to a condition known as torsades de pointes, an abnormal heart rhythm. Prolongation of the PR interval may also lead to an abnormal heart rhythm known as heart block. With torsades de pointes or with heart block, patients may experience lightheadedness, fainting, or abnormal heart beats. In some cases, torsades de pointes may progress to a life-threatening irregular heart beat known as ventricular fibrillation.

Review of the data is ongoing. Preliminary findings suggest that some patients using Invirase and Norvir may be at an increased risk for heart abnormalities leading to irregular heart rhythms. For example, the risk for torsades de pointes may be increased in patients who are also using medications known to cause a heart disturbance called QT interval prolongation. The risk may also be increased in patients who have a history of QT interval prolongation.

Patients using Invirase should talk to their health care professional about any questions or concerns they have about Invirase. Patients and health care professionals should report any side effects from the use of Invirase to the FDA’s MedWatch program:
http://www.fda.gov/safety/MedWatch/default.htm

Invirase is an antiretroviral medication that was first approved in 1995. Invirase is used in combination with Norvir and other antiretroviral medicines to treat HIV in adults. Invirase does not cure HIV infection, may not prevent you from developing HIV-related illnesses, and may not prevent you from spreading HIV to other people.

This early communication is in keeping with FDA’s commitment to inform the public about ongoing safety reviews of drugs. FDA will communicate its findings to the public as soon as the review is complete.

Invirase is marketed by San Francisco-based Genentech, a subsidiary of the Roche Group. Norvir is marketed by Abbott Park, Ill.-based Abbott Laboratories.

For more information: http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm201221.htm

How quickly an HIV patient’s immune system deteriorates may not affect the outcome of the illness, a study has found, and this could help change current guidelines for treatment of the disease.

There is no cure for the human immunodeficiency virus (HIV) that causes AIDS, but combinations of drugs can keep the virus from replicating and damaging the immune system.

Doctors normally do not start treatment until there is some evidence of damage to this system, measured by counting the number of immune cells, called CD4 T-cells.

In developed countries, HIV treatment usually begins when CD4 numbers drop below 350 cells per microlitre of blood.

Some treatment guidelines also recommend that therapy be started more quickly for people whose CD4 counts decline rapidly.

But the study, involving an international team of researchers, found that the pace of decline did not result in any substantial differences to the outcome of the illness.

“What we looked at was whether it matters how a person reached his current CD4 cell count, whether the CD4 count declined very quickly, or very slowly, and we found that the CD4 cell dynamics don’t provide additional information about the patient’s prognosis on top of the current CD4 cell count,” said Marcel Wolbers of the Hospital for Tropical Diseases in Ho Chi Minh City in Vietnam.

Wolbers, a biostatistician and one of the principal investigators of the study, and his colleagues examined records of 2,820 HIV patients from Australia, Canada and Europe with varying rates of CD4 declines.

They found no significant differences in their progression to AIDS or the number of deaths.

“The current rate of CD4 cell decline is neither a strong predictor of whether a person is progressing to AIDS or dies, nor does it predict future CD4 cell decline,” he said. “Therefore, it shouldn’t guide clinical decisions, in particular the decision whether to initiate (drug) therapy or not.

“A further implication of our study is that the patient’s CD4 cell count should be monitored regularly regardless of the prior rate of CD4 decline and that should be done according to current guidelines, i.e. every three to six months.”

The study, published in the latest issue of PLoS Medicine, is available for free at http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000239.

(Reporting by Tan Ee Lyn, Editing by Ron Popeski)