CONTACT:  NHLBI Press Office
          (301) 496-4236

August 31, 1995


Statement Offers Guidance to Physicians

NHLBI PANEL REVIEWS SAFETY OF CALCIUM CHANNEL BLOCKERS


Short-acting nifedipine, a type of calcium channel blocker
prescribed for hypertension and certain heart disorders,
should be used with "great caution (if at all)," especially at
higher doses, concludes the National Heart, Lung, and Blood
Institute in a statement for health professionals.

The statement is based on a review of the available scientific
evidence on the safety of calcium channel blockers, including
smaller clinical trials and several new studies.  The review
was conducted by an ad hoc panel on calcium channel blockers
convened by the NHLBI in June 1995.  Among the studies
reviewed is a meta-analysis of 16 trials of nifedipine in
patients with coronary heart disease, published in the
September 1 issue of the American Heart Association's journal
"Circulation."  The meta-analysis, which pooled the results of
the 16 studies, revealed an increase in deaths among patients
taking nifedipine in doses of 80 mg. or greater. 

The recommendation concerning nifedipine was one of several
contained in the NHLBI statement, which is intended to help
guide physicians and other health professionals as they advise
their patients about the safety of calcium channel blockers.

"This statement is intended to provide a much-needed
perspective on the safety and effectiveness of calcium channel
blockers," said NHLBI Director Dr. Claude Lenfant.  

"It will help physicians counsel their patients, many of whom
panicked when the results of a case control study of calcium
channel blockers were misinterpreted," added Dr. Lenfant.

The statement acknowledges that calcium channel blockers are
effective in the relief of certain heart disorders such as
angina pectoris and some arrhythmias and in the reduction of
blood pressure.  It cautions, however, that like most drugs,
calcium channel blockers have multiple effects, so it is
important to establish the risks as well as the major
benefits.  There are three sub-classes of calcium channel
blockers.  The following is a list of classes and examples of
each:  dihydropyridines (nifedipine), phenylalkylamines
(verapamil), and benzothiazepines (diltiazem).  These three
"sub-classes" are chemically distinct and have some
pharmacological differences.  In addition, several calcium
channel blockers have both short-acting (requiring several
daily doses) and long-acting (once daily) forms.  The NHLBI
statement concludes:

*The nifedipine finding cannot necessarily be generalized to
any other calcium channel blocker including longer-acting
dosage forms of nifedipine and short-acting formulations of
other drugs such as diltiazem and verapamil.  The latter two
drugs were associated with an increased risk of heart attack
in a University of Washington case-control study of
hypertensive patients.  However, diltiazem and verapamil were
not associated with increased risk of death or heart attack in
other studies, including well-designed clinical trials in
heart attack patients, a group at high risk of recurrent heart
attacks.

*The results of large-scale randomized clinical trials, such
as the ongoing Antihypertensive and Lipid-Lowering Treatment
to Prevent Heart Attack Trial (ALLHAT), are essential to the
ultimate resolution of the issues of safety and effectiveness.

*Health professionals should review current treatment
guidelines, including the fifth Report of the Joint National
Committee on Detection, Evaluation, and Treatment of High
Blood Pressure (JNC V).  According to JNC V, which is a
document produced by the NHLBI's National High Blood Pressure
Education Program, calcium channel blockers and other
alternative drugs should be reserved for special situations or
when diuretics and beta blockers have proved unacceptable or
ineffective.

*Current uncertainties about the choice of drugs for the
treatment of hypertension should not interfere with efforts to
achieve blood pressure control.  It has already been proven
that treating hypertension prevents stroke and heart attack.

The complete text of the NHLBI statement will be available
online (fido.nhlbi.nih.gov or gopher://gopher.nhlbi.nih.gov/). 
Members of the press can call (301) 496-4236 for the
statement.
.