Mefenamic acid (ponstan) pharmacokinetic ,adminstration ,dosage,side effect & contraindication,and general information

1. By
Younis Saad
Ula Salih
Noor Alhuda Khalaf
Ghufran Jabbar

2.  Introduction
 Pharmacodynamics
 Pharmacokinetics
 Uses
 Dosage & Administration
 Side Effects
 Brand names
 References & Sources

3. What is mefenamic acid?
Mefenamic acid is a non-steroidal
anti-inflammatory
drug used to treat pain.
It is typically prescribed for
oral administration.

4.  Mefenamic Acid is a white
to greyish-white, odorless,
microcrystalline powder with
a melting point of 230° to
231°C and water solubility of
0.004% at pH 7.1. The chemical
name is N-2,3-xylylanthranilic
acid. The molecular weight is
241.29.

5.  Its molecular formula is
C15H15N02 and the structural formula of
Mefenamic Acid is:

6. Mefenamic Acid is a non-steroidal anti-inflammatory
drug (NSAID) that exhibits anti-inflammatory,
analgesic, and antipyretic
activities in animal models. The mechanism
of action of Mefenamic Acid, like that of
other NSAIDs, is not completely understood
but may be related to prostaglandin
inhibition.

7. Absorption
usually reaches peak plasma levels 2 to 4 hours after
oral administration with a half life of 2 hours.
Distribution
Mefenamic acid and its metabolites are firmly bound to
plasma proteins.

8. MEFENAMIC ACID has demonstrated analgesic, anti-inflammatory
and antipyretic properties in human clinical studies
and in classical animal test systems. These effects may be due to
its dual action on prostaglandins. It inhibits the enzymes of
prostaglandin syntheses and also antagonises the actions of
prostaglandin at the receptor sites. These effects may also be
responsible for its effectiveness in the treatment of primary
dysmenorrhoea.

9. Mefenamic acid metabolism is predominantly mediated
via cytochrome P450 CYP 2C9 in the liver. Patients
who are known or suspected to be poor CYP2C9
metabolisers should be administered mefenamic acid
with caution as they may have abnormally high plasma
levels due to reduced metabolic clearance.
Metabolism I 3-hydroxymethyl Mefenamic Acid
Metabolism II 3-carboxy Mefenamic Acid

10. Elimination
Following a single dose, 67% of the
total dose is excreted in the urine as
unchanged drug or as one of the two
metabolites. 20% to 25% of the dose is
excreted in the faeces during the first
three days.

11. Mefenamic acid is used for:
 Treatment of primary dysmenorrhoea
 Inflammation and fever
 soft tissue and dental pain.
Mefenamic acid is an NSAID, NSAIDs treat the symptoms
of pain and inflammation. They do not treat the disease that
causes those symptoms.

12.  Dysmenorrhoea
(500 mg) three times daily from the onset of pain and
continued for the usual duration of pain.
 Menorrhagia
(500 mg) three times daily. Therapy should not be
continued for more than 7 days except on the advice of a
physician.
 Other Indications
(500 mg) three times daily

13. Dental pain or soft tissue
500 mg three times daily
Children
250 mg three times daily
Not recommended for children under 14 years of age.
Food(before/after)
Should be taken with food.

14. Symptoms
Symptoms of over dosage are related to the amount of
drug ingested and range from gastrointestinal
discomfort and diarrhea to seizures, acute renal failure,
vertigo, hallucination, coma and death. Plasma levels
of up to 210 μg/mL (therapeutic range 1 to 10 μg/mL)
have been reported resulting in repeated generalised
convulsions, but are not generally useful for evaluation
and management of over dosage.

15. There is no specific antidote for mefenamic acid overdose.
Treatment is symptomatic and supportive, including fluid
replacement and IV access especially to patients who are
dehydrated or unable to ingest adequate fluids.
Because mefenamic acid and its metabolites are firmly
bound to plasma proteins, haemodialysis, and peritoneal
dialysis may be of little value.

16. All medicines may cause side effects, but many
people have no, or minor, side effects.
Constipation, diarrhea, dizziness, gas,
Headache, heartburn, nausea, stomach upset.
Severe allergic reactions
Rash, Hives, Itching, trouble breathing,
tightness in the chest, swelling of the
mouth, face, lips, or tongue.

17. Be careful if you are pregnant there a potential
risk to the fetus.
the benefits from use in pregnant women may be acceptable
despite the risk (e.g., if the drug is needed in a life threatening
situation or for a serious disease for which safer drugs cannot
be used or are ineffective).
The inhibition of prostaglandin synthesis by NSAIDs
may adversely affect pregnancy. Epidemiological
studies suggest an increased risk of spontaneous
abortion after use of prostaglandin synthesis inhibitors
in early pregnancy. In animals, administration of
prostaglandin synthesis inhibitors has been shown to
result in increased pre- and post-implantation loss.

18. NSAIDs given during the latter part of pregnancy may
cause closure of the fetal ductus arteriosus, fetal renal
impairment, inhibition of platelet aggregation. Continuous
treatment with NSAIDs during the last trimester of
pregnancy should only be given on sound indications.
During the last few days before expected birth, agents with
an inhibitory effect on prostaglandin synthesis should be
avoided.
It is not known if mefenamic acid or its metabolites
crosses the placenta. Since there are no adequate and well-controlled
studies in pregnant women

19. Use in Lactation
Trace amounts of mefenamic acid may be present in breast
milk and transmitted to the nursing infant. Thus mefenamic
acid should not be taken by the nursing mother because of
the effects of this class of drugs on the infant
cardiovascular system.

20.  1. Patients showing evidence of chronic inflammation
and/or active ulceration of either the upper or lower
gastrointestinal tract and patients with pre-existing renal
disease.
 2. Patients in whom aspirin and/or other NSAIDs have
induced symptoms of bronchospasm, allergic rhinitis
because the potential exists for cross-sensitivity.
 3. Patients with impaired renal function or hepatic failure.

21.  4. Patients previously experiencing diarrhea on taking
this drug.
 5. Patients who have previously exhibited
hypersensitivity to mefenamic acid .
 6. Patients with severe heart failure.

22.  Aspirin
Mefenamic acid interferes with the anti-platelet effect
of low-dose aspirin, and thus may interfere with
aspirin’s prophylactic treatment of cardiovascular
disease.
 Corticosteroids
Concurrent use with NSAIDs may increase the risk of
gastrointestinal ulceration or bleeding.

23.  Cyclosporin or Tacrolimus
Concomitant administration with NSAIDs increases the
risk of nephrotoxicity.
 Hypoglycaemic agents
There have been reports of changes in the effects of oral
hypoglycaemic agents in the presence of NSAIDs.
Therefore, mefenamic acid should be administered with
caution in patients receiving insulin or oral
hypoglycaemic agents.

24.  Lithium
Mefenamic acid has produced an elevation of plasma
lithium levels and a reduction in renal lithium clearance.
Thus, when mefenamic acid and lithium are administered
concurrently, patients should be observed carefully for
signs of lithium toxicity.
 Methotrexate
Caution is advised when methotrexate is administered
concurrently with NSAIDs, including mefenamic acid,
because NSAID administration may result in increased
plasma levels of methotrexate, especially in patients
receiving high doses of methotrexate.

25. Mefenamic acid is internal administration
solid formulation: supplied in PVC/Al blister packs of 20
or 50 capsules and in bottles of 50 capsules.
liquid formulation: 120 ml
Examples:
Beafemic, Mefalth, Mefivan, Ponstel, Ponstan,
Ponstal, Parkemed, Revalan, Mafepain,

26. Mefamed, Potalon, Dolfenal, Meyerdonal,
Alfoxan, Fenamin, Pangesic, Mefanorm, Meftal,

27. References :
1. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC27206
41/
2. "Side effects for Mefenamic Acid". Medline Plus.
National Institutes of Health.
3. http://www.drugs.com/ppa/mefenamic-acid.
html
4. http://www.eci2012.net/ .1

28. 5. http://www.drugs.com/ppa/mefenamic-acid.
html
6. http://www.drugsupdate.com/generic/view/
285
Sources :
 MedlinePlus Drug Information: Mefenamic Acid. Last
accessed September 28, 2005.
 Ponstel Pharmacology, Pharmacokinetics, Studies,
Metabolism - Mefenamic Acid - RxList Monographs. Last
accessed September 28, 2005.