Download 門診處方討論 主講者:黃意文

門診處方討論
Nifedipine用於安胎
主講者:黃意文
Nifedipine
❃OVERVIEW
A.
B.
C.
Nifedipine is a calcium channel antagonist.
Nifedipine is a vasodilator with antianginal and
antihypertensive effects. It acts by blocking the postexcitation release of calcium ions into cardiac and vascular
smooth muscle, thereby inhibiting the activation of ATPase on
myofibril contraction.
The usual adult oral dose in angina and hypertension is 10 to
20 milligrams (mg) three times daily or 30 to 60 mg extended
release daily; doses above 180 mg/day regular release or 90
to 120 mg extended release are not recommended. A
maximum daily dose of 60 mg immediate-release nifedipine
for patients with essential hypertension or chronic angina
pectoris has been recommended in 1997 by the German
Health Authority (BfArM) due to a dose-dependent increase in
heart-related complications and incidence of death.
Premature labor
Premature labor
Premature labor
Premature labor
❄ PREMATURE LABOR
1.OVERVIEW:
FDA APPROVAL: Adult, no; pediatric, no
USP RATING: Not rated
EFFICACY: Adult, effective
DOCUMENTATION: Adult, good
2.SUMMARY:
Tocolytic effect similar to standard betamimetic agents
Minimal maternal/fetal adverse effect
Investigation status; not recommended for
general use
PRETERM LABOR

TREATMENT SUMMARY
 A. GENERAL: Treatment is aimed at termination of
premature uterine contractions with tocolytics,
administration of steroids for fetal lung maturation, and,
when appropriate, group B streptococcus prophylaxis to
decrease risk of maternal and neonatal infection. Bedrest,
hydration, and pelvic rest have not been proved effective
and are not recommended routinely.
 B. TOCOLYTICS: Cornerstone of primary pharmacologic
management. May lengthen duration of pregnancy by
several days to allow time for steroid administration and
possible transfer to a tertiary care facility. Choice of
agent should be based on maternal condition, drug side
effects, and gestational age. Use in consultation with
obstetrician.
Nifedipine
GENERAL INFORMATION: With their potential efficacy for
inhibiting contractility in myometrial tissue, calcium channel
blockers may be useful in prolonging PRETERM LABOR leading to
improved survivability and morbidity in premature infants. Current
data suggests this is achieved with minimal adverse effects to the
mother or fetus. Nifedipine is the most widely studied member of
this class, and it has shown comparable effectiveness when
compared to standard beta sympathomimetic agents such as
ritodrine and terbutaline. Additionally, some evidence suggests
that calcium antagonists might be combined with standard
therapies to control maternal side effects induced by
sympathomimetics. However, general application cannot be
recommended and their use as tocolytics should be considered
inconclusive and investigational (Steer, 1999; Monga & Creasy,
1995; McCombs, 1995; Higby et al, 1993; Leonardi & Hankins,
1992).
建議劑量
CALCIUM CHANNEL
BLOCKERS:
NIFEDIPINE: ADULTS: 30
mg loading dose, then 10
to 20 mg orally Q4-6H.
Nifedipine與Ritodrine的比較
A randomized trial (n=52) failed to demonstrate an efficacy difference
between ritodrine (0.05 to 0.35 milligram/minute IV for 12 hours, then
5 mg every 3 hours orally) and nifedipine (loading dose of 10 mg
sublingually plus 20 mg orally, then 10 to 20 mg orally every 4 to 6
hours) in terms of postponing delivery or neonatal outcomes. However,
nifedipine-treated subjects experienced significantly fewer and less
severe adverse effects (Garcia-Velasco et al, 1998). Data from another
trial (n=102) also support equivalent tocolytic efficacy of nifedipine and
ritodrine. Dosing consisted of 0.2 to 0.4 milligram/minute IV ritodrine
with conversion to oral ritodrine 80 mg 3 times daily, or 30 mg
sublingual nifedipine followed by oral nifedipine 40 to 120 mg daily.
During the first 7 days of therapy, the incidence of adverse effects was
significantly higher in the ritodrine group (Koks et al, 1998).
Nifedipine與Ritodrine的比較
Nifedipine was just as effective as ritodrine for delaying delivery for
either 48 hours, 7 days, or until the 36th week of gestation
(Kupferminc et al, 1993; Ferguson et al, 1990). Regimens compared
sublingual nifedipine (10 to 50 mg), with a maintenance dose of 20mg
every 4 to 8 hours. Ritodrine was initiated at 50 mcg/minute, increased
by 15 to 50 mcg/minute until a maximum of 300 to 350 mcg/minute
was administered, uterine contractions stopped, or unacceptable side
effects occurred. Delivery was delayed more than 48 hours in 83% to
84% of the patients treated with nifedipine and 72% to 77% in
patients treated with ritodrine. Maternal side effects were less frequent
with nifedipine. Fetal and neonatal outcomes were similar for both
treatments and studies.
Summery
1.目前FDA核准用於安胎藥物只有Ritodrine
2.Nifedipine-treated subjects experienced
significantly fewer and less severe
adverse effects
3.Maternal side effects were less frequent
with nifedipine
資料來源~
1.Micromedex
2.Obstetrics and Gynecology:November
2002 Volume 100, Number 5, Part 1
Pages 1020 - 1037