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Risk
Of Prolonged QT Intervals Prompts Droperidol Warning
The manufacturer of droperidol (Inapsine)—an antipsychotic
with antiemetic properties—has added a “black
box” warning and other revisions to its labeling
at the behest of the FDA. The changes were required because
of the drug’s risk of fatal cardiac arrhythmias,
including prolonged QT intervals
and torsades de pointes, at dosages at or below the recommended
ranges.
Previously,
droperidol’s labeling had warned of cases of sudden
death at high doses (25 mg or more) in patients at risk
for arrhythmias. But in the last year, serious adverse
cardiac events, including deaths, had occurred in patients
with no known risk factors and within the approved dosage
range. In
addition to the black box warning, the manufacturer has
revised droperidol’s labeling to reinforce the drug’s
approved use—reducing the incidence of nausea and
vomiting associated with surgical and diagnostic procedures—and
to clarify its dosage. The revisions stress that the drug
is to be reserved
for patients who do not respond to other treatments.
U.S.
Food and Drug Administration MedWatch. “Inapsine
(droperidol).” 2001.
www.fda.gov/medwatch/safety/2001/safety01.htm#inapsi (7
Dec. 2001).
[TOP]
Clot-Buster
Approved For Clearing Central Caths
The thrombolytic agent alteplase (Activase), commonly
used to treat acute MI, has been approved for restoring
function to central venous access devices, as assessed
by the ability to withdraw blood. Such blockages, unless
they are cleared pharmacologically, require that the catheter
be removed and
replaced surgically.
For
this new indication, alteplase will be marketed under
the brand name CathFlo Activase with a separate dosing
regimen and vial. Alteplase was tested in a blinded, placebo-controlled
trial involving 149 patients whose central venous access
devices had been occluded for up to 24 hours. Catheter
function was restored in 74% of patients given one 2 mg
dose of alteplase
vs. 17% with placebo. A second dose of the thrombolytic
restored function in 90%. (Dwell time for each dose was
two hours.) The most serious adverse events were sepsis,
GI bleeding, and venous thrombosis.
Based
on a news release by Genentech, Inc., Sept. 4, 2001: “FDA
approves
CathFlo Activase (alteplase) to restore function to central
venous access
devices as assessed by the ability to withdraw blood.”
www.genentech.com/news/2001/20010904-151641.html (1 Oct.
2001).
[TOP]
15-Minute
Infusion Treats Hypercalcemia Of Malignancy
A new-generation intravenous bisphosphonate drug, zoledronic
acid (Zometa), has been approved for the treatment of
hypercalcemia of malignancy. In clinical studies, it demonstrated
a better response—with a considerably shorter infusion
time—than therapy with an earlier product, pamidronate
disodium (Aredia).
Zoledronic
acid is given 4 mg IV for a minimum of 15 minutes, compared
with pamidronate’s recommended infusion rate of four
to 24 hours. Patients being treated with zoledronic acid
must be adequately rehydrated before administration. Patient’s
renal function must be carefully monitored because of
the risk of clinically significant deterioration in renal
function, which
may progress to renal failure. The dose therefore shouldn’t
exceed 4 mg, and the duration of the infusion should be
no less than 15 minutes. The most common adverse effect
is fever.
Novartis
Pharmaceuticals Corp. ”Zometa approved.” 2001.
www.zometa.com/us/us.asp (28 Aug. 2001).
[TOP]
Guidelines
Aim To Prevent Steroid-Induced Osteoporosis
Citing shortfalls in providers’ knowledge about glucocorticoid-induced
osteoporosis, the American College of Rheumatology has
issued new recommendations for the prevention and treatment
of this adverse effect. Glucocorticoids, which include
dexamethasone, hydrocortisone, and prednisone, are used
to treat rheumatoid arthritis, asthma, and other inflammatory
conditions. But such drugs raise the risk of osteoporosis
and
resultant fractures in both women and men.
The
guidelines recommend the use of a bisphosphonate—either
alendronate sodium (Fosamax) or risedronate sodium (Actonel)—in
conjunction with calcium and vitamin D supplements for
all men and postmenopausal women starting
three months of glucocorticoid therapy. Men and postmenopausal
women already on long-term glucocorticoids should be given
the supplements; gonadal sex hormone replacement, if needed;
and a bisphosphonate if they have
osteoporosis. Premenopausal women should be advised about
appropriate contraception if a bisphosphonate is being
considered, since the drug may pose a risk to a fetus.
American
College of Rheumatology. “Recommendations for the
prevention and
treatment of glucocorticoid-induced osteoporosis. 2001
update.” 2001. www
.rheumatology.org/research/guidelines/osteo/osteoupdate.html
(23 Jul. 2001).
[TOP]
Hormonal
Vaginal Ring Provides Once-Monthly Contraception
Recently approved NuvaRing is the first birth-control
product in the form of a vaginal contraceptive ring that
releases a combination of estrogen (ethinyl estradiol)
and progestin (etonogestrel) at a continuous low dose.
The ring is a soft, flexible, colorless polymer that’s
about two inches in diameter. Patients must use it as
directed for maximum effectiveness, which was 98% –
99% in a year-long study. The ring is inserted once a
month for three weeks, and then is removed for one week,
when the patient has her period. If the ring comes out
accidentally and isn’t reinserted within three hours,
an additional form of contraception (male condom or spermicide)
must be used until the ring has been back in place for
seven days.
Adverse
effects of NuvaRing may include vaginal discharge, vaginitis,
and irritation. The product shouldn’t be used in
women with cardiovascular disease, thrombophlebitis or
thromboembolic disorders, certain types of cancer, or
known or suspected pregnancy. Cigarette smoking can increase
the
risk of cardiovascular adverse effects.
U.S.
Food and Drug Administration. “FDA approves first
hormonal vaginal
contraceptive ring.” 2001. www.fda.gov/bbs/topics/answers/2001/ans01107.html
(9 Oct. 2001).
[TOP]
Did
The Diuretic Do It?
A 74-year-old patient with increasing dyspnea is diagnosed
with mild congestive heart failure. She’s given the
diuretic furosemide (Lasix) 40 mg PO qd, with good results.
But two weeks later she returns with an “extremely
itchy” rash and insists the diuretic is to blame.
Asked again about drug allergies, she recalls having once
had a reaction to a sulfa drug. Could there be a connection?
Portions of furosemide’s molecular structure are
similar to that of sulfonamide antibiotics, or sulfa drugs.
As a result, patients allergic to sulfas may have a sensitivity
reaction to the diuretic. This is the probable cause of
the patient’s rash. Other loop diuretics besides
furosemide and many thiazide diuretics contain a sulfa
component, as well. Although patients allergic to sulfa
drugs generally tolerate these agents, it’s prudent
to keep this risk factor in mind.
Potassium-sparing diuretics, such as amiloride HCl (Midamor,
others), spironolactone (Aldactone, others), or triamterene
(Dyrenium), may be a better choice for this patient because
that drug class is not associated with a sulfa hypersensitivity
reaction.
Sources:
1. Micromedex Healthcare Series. (2001). Greenwood Village,
CO:
Micromedex Inc. 2. Craig, T. J., & Mende, C. (1999).
Common allergic and
allergic-like reactions to medications. Postgrad Med,
105(3), 173.
THE AUTHOR
LINDA M. PORTERFIELD, RN, PhD, is a clinical pharmacologist
and director of
cardiovascular research at Arrhythmia Consultants in Memphis.
She works
with her husband, James Porterfield, MD, FACC, who is
a cardiologist and
electrophysiologist.
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