Transcript Here are some of these formulations

A Calcium Channel Blocker
Prepared By
MARIAM SALEH ALAMRO
Physical Properties :
Nifedipine is a:
* yellow
*crystalline
*water insoluble
substance .
Its structure is as follow :
Formulation :
The drug is available as capsules
or extended release tablets . They
must be swallowed as whole not
chewed, divided nor crushed .
Here are some of these
formulations :
Adalat
Procardia XL
Pharmacokinetics :
* Completely absorbed after oral
administration. (extended release
tablets must be taken on an
empty stomach 1 hour bofore or
2 hours after the meal . In
contrast, capsules can be taken
either with food or without)
* Widely distributed. (found in
hippocampal neurons of
experimental rats)
* Metabolized mainly in
gastrointestinal tract and to
lesser extent in the liver. The
metabolites are inactive and
water soluble.
* Excreted mainly in the urine.
* Highly protein binding .
* Half life is 2 hours.
* The bioavailability is 45-56 %
Pharmacodynamics :
* Mechanism of Action :
Smooth muscle cells and cardiac
cells need calcium to contract.
Nifedipine is a calcium ion influx
inhibitor preventing it from entering
the cells so relaxation results .
* Effect :
In Angina :
It dilates coronary arteries and increases
myocardial oxygen delivery . So, the
condition gets better.
In Hypertension :
The reduction in calcium influx by
nifedipine causes arterial vasodilation and
decreases peripheral vascular resistance
which results in reduced arterial blood
pressure.
Uses:
Major :
* Angina .
* Hypertension .
Minor :
* Migraine headache .
* Raynaud’s syndrome .
* Congestive heart failure .
* Preterm labour .
Recommended Dose :
The usual starting dose is 10 milligrams ,
3 times a day. Doses can be increased
according to patients needs but doses
above 120 milligrams per day are not
recommended .
N.B. If you miss a dose take it as soon as
you remember it . If it is almost time for
the next dose , skip the missed dose and
continue your regular dosing schedule .
Never take double dose.
Adverse Effects :
Common :
* Edema .
* Headache .
Less Likely :
* Chest pain .
* Diarrhea .
* Rhinitis .
* Urinary frequency .
* Arthralgia .
Contraindications :
* Known hypersensitivity reaction to
nifedine .
* History of myocardial infarction .
* In pregnant and nursing mothers .
* Severe gastrointestinal narrowing .
* Hepatic dysfunction .
Precautions :
* Hypotension .
* Periphral edema .
* Over 65 years .
* Heart, liver or kidney diseases .
Drug Interactions :
1- Grapefruit Juice :
* Increases the bioavailability of
nifedipine and the volume of
distribution.
* It causes a delay gastric
emptying .
 Interferes with nifedipine
metabolism .
2- Antifungal Drugs : (eg.
Ketoconazole)
Are CYTP450 inhibitors and can
inhibit the metabolism of nifedipine
(increase its level)
3-Antitubercular Drugs : (eg.
Rifapentine)
An inducer of CYTP450 and can
induce the metabolism of nifedipine
(decrease its level)
2 & 3  Adjust the dose
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