What is diclofenac and misoprostol, and how does it work (mechanism of action)?
Arthrotec is a combination of diclofenac and
misoprostol. Diclofenac is a
nonsteroidal anti-inflammatory drug (NSAID) similar
to ibuprofen (Motrin or Advil), naproxen (Naprosyn), and others that is used to
treat inflammation, pain, and fever. Diclofenac, like other NSAIDs works by
inhibiting the production of prostaglandins. Prostaglandins are a family of
chemicals produced by the cells of the body that promote inflammation, pain, and
fever. In addition, they support the function of platelets that are necessary
for the clotting of blood, and protect the lining of the stomach from the
damaging effects of acid.
Prostaglandins are produced by the enzyme cyclooxygenase (Cox). There actually are two Cox enzymes, Cox-1 and Cox-2. Both
enzymes produce prostaglandins that promote inflammation, pain, and fever.
However, only Cox-1 produces prostaglandins that support platelets and protect
the stomach. Diclofenac blocks both Cox enzymes and reduces prostaglandins
throughout the body. As a consequence, ongoing inflammation, pain, and fever are
reduced. Since prostaglandins that protect the stomach and support platelets and
blood clotting also are reduced, NSAIDs can cause ulcers in the stomach and
promote bleeding. Misoprostol is a synthetic (man-made) prostaglandin that
stimulates secretion of mucus in the gastrointestinal tract. Mucus protects the
lining of the stomach from acid. Misoprostol has been shown to reduce the
frequency of ulcers of the stomach caused by NSAIDs. Arthrotec was approved by
the FDA in December 1997.
What brand names are available for diclofenac and misoprostol?
Arthrotec
Is diclofenac and misoprostol available as a generic drug?
No
Do I need a prescription for diclofenac and misoprostol?
Yes
What are the side effects of diclofenac and misoprostol?
Arthrotec has the side effects of diclofenac and misoprostol. The most common side effects are:
- stomach pain,
- diarrhea,
- dyspepsia,
- nausea, and
- flatulence.
Diarrhea and abdominal pain may resolve after 2-7 days.
Magnesium containing antacids worsen diarrhea caused by misoprostol. Taking
Arthrotec with food and avoiding antacids containing magnesium may reduce the
occurrence of diarrhea.
Other important side effects include
- gastrointestinal ulcers and bleeding;
- liver dysfunction;
- severe skin reactions,
- allergic reactions, and
- kidney failure.
Severe bronchospasms may occur in patients with
aspirin-sensitive asthma. Like other NSAIDS, Arthrotec may cause
heart attacks
and strokes; accumulation of fluid and worsen heart failure; cause or worsen
hypertension and
kidney failure.
What is the dosage for diclofenac and misoprostol?
For osteoarthritis the recommended dose is Arthrotec 50 given
three times daily. Patients who cannot tolerate this regimen may be treated with
Arthrotec 50 or 75 twice daily. The recommended dose for treating rheumatoid arthritis is Arthrotec 50 given 3-4 times daily. If this regimen is not
tolerated, Arthrotec 50 or 75 twice a day may be used. Administering Arthrotec
twice daily is less effective for preventing ulcers. Taking Arthrotec with food
may reduce stomach upset. It is recommended that Arthrotec not be taken with
alcohol because of the increased risk for ulcers.
Which drugs or supplements interact with diclofenac and misoprostol?
(Please also see the drug information for
diclofenac.) Diclofenac is generally used with caution in patients taking blood
thinning medications (anticoagulants), such as warfarin (Coumadin), because of
the increased risk of bleeding.
Patients taking lithium
(Eskalith,
Lithobid) can develop toxic blood levels of lithium because diclofenac may inhibit the elimination of lithium from the
body by the kidney.
Side effects from methotrexate (Rheumatrex, Trexall) and cyclosporine also
may be increased by diclofenac.
Diclofenac may reduce the effectiveness of blood pressure-lowering drugs.
Since prostaglandins are important in the control of blood pressure.
Antacids reduce the absorption of misoprostol and may delay absorption of
diclofenac. Magnesium-containing antacids worsen misoprostol-associated
diarrhea. Therefore, Arthrotec should not be administered with
magnesium-containing antacids.
Combining NSAIDs with angiotensin receptor blockers (for example, valsartan [Diovan],
losartan [Cozaar], irbesartan [Avapro]) or angiotensin converting enzyme
inhibitors (for example, enalapril [Vasotec], captopril [captopril]) in patients
who are elderly, volume-depleted (including those on diuretic therapy), or with
poor kidney function may result in reduced kidney function, including kidney
failure. These effects usually are reversible.
Diclofenac may increase blood levels of digoxin (Lanoxin)and lead to digoxin
toxicity. Digoxin levels should be monitored.
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Is diclofenac and misoprostol safe to take if I’m pregnant or breastfeeding?
Since misoprostol can cause abortions, Arthrotec should not
be used by women who are pregnant. Women also should avoid
pregnancy for one month
or one menstrual cycle after discontinuing Arthrotec.
Diclofenac and misoprostol are secreted in
breast
milk. Arthrotec is not recommended for use by nursing mothers.
What else should I know about diclofenac and misoprostol?
What preparations of diclofenac and misoprostol are available?
Tablets (diclofenac/misoprostol): Arthrotec 50 (50
mg/200 g), Arthrotec 75 (75 mg/200 g) .
How should I keep diclofenac and misoprostol stored?
The tablets should be kept at room temperature, 15 C – 30 C
(59 F – 86 F).