Johnstal

Johnstal Uses, Dosage, Side Effects, Food Interaction and all others data.

Johnstal, an anthranilic acid derivative, is a prototypical NSAID. It reversibly inhibits the cyclooxygenase-1 and cyclooxygenase-2 (COX-1 and COX-2) enzymes, thus resulting in reduced synthesis of prostaglandin precursors. It has analgesic and antipyretic properties with minor anti-inflammatory activity.

Johnstal, an anthranilic acid derivative, is a member of the fenamate group of nonsteroidal anti-inflammatory drugs (NSAIDs). It exhibits anti-inflammatory, analgesic, and antipyretic activities. Similar to other NSAIDs, mefenamic acid inhibits prostaglandin synthetase.

Trade Name Johnstal
Generic Mefenamic acid
Mefenamic acid Other Names Acide méfénamique, ácido mefenámico, Acidum mefenamicum, Mefenamic acid, Mefenaminsäure
Type
Formula C15H15NO2
Weight Average: 241.2851
Monoisotopic: 241.110278729
Protein binding

90%

Groups Approved
Therapeutic Class Drugs for Osteoarthritis, Drugs used for Rheumatoid Arthritis, Non-steroidal Anti-inflammatory Drugs (NSAIDs)
Manufacturer
Available Country Taiwan
Last Updated: September 19, 2023 at 7:00 am
Johnstal
Johnstal

Uses

Johnstal is used in mild to moderate pain including headache, dental pain, postoperative and postpartum pain, dysmenorrhoea, menorrhagia, in musculoskeletal and joint disorders such as osteoarthritis and rheumatoid arthritis; and in children with fever and juvenile idiopathic arthritis.

Johnstal is also used to associated treatment for these conditions: Mild pain, Primary Dysmenorrhoea, Gastrointestinal cramps, Moderate Pain

How Johnstal works

Johnstal binds the prostaglandin synthetase receptors COX-1 and COX-2, inhibiting the action of prostaglandin synthetase. As these receptors have a role as a major mediator of inflammation and/or a role for prostanoid signaling in activity-dependent plasticity, the symptoms of pain are temporarily reduced.

Dosage

Johnstal dosage

As with other NSAIDs, the lowest dose should be sought for each patient. Therefore, after observing the response to initial therapy with Johnstal, the dose and frequency should be adjusted to suit an individual patient's needs.Administration is by the oral route, preferably with food.

  • Adult: A 500 mg dose should be given to adults up to three times (1.5 g total) per day.
  • Infants over 6 months: 25 mg/kg of body weight daily in divided doses for not longer than 7 days.

Side Effects

In patients taking Johnstal or other NSAIDs, the most frequently reported adverse experiences include : abdominal pain, constipation, diarrhoea, dyspepsia, flatulence, gross bleeding/perforation, heartburn, nausea, GI ulcers, vomiting, abnormal renal function, anaemia, dizziness, oedema, elevated liver enzymes, headache, increased bleeding time, pruritus, rash and tinnitus.

Toxicity

Oral, rat LD50: 740 mg/kg. Symptoms of overdose may include severe stomach pain, coffee ground-like vomit, dark stool, ringing in the ears, change in amount of urine, unusually fast or slow heartbeat, muscle weakness, slow or shallow breathing, confusion, severe headache or loss of consciousness.

Precaution

NSAIDs should be prescribed with extreme caution in those with a prior history of ulcer disease or gastrointestinal bleeding. To minimise the potential risk for an adverse GI event, the lowest effective dose should be used for the shortest possible duration. In cases with pre-existing advanced kidney disease, treatment with Johnstal is not recommended.

Interaction

Concomitant use with CYP2C9 isoenzyme inhibitors may alter safety and efficacy of mefenamic acid. May enhance methotrexate toxicity. Reduced BP response to ACE inhibitors or angiotensin II receptor antagonists. Increased risk of serious GI events with aspirin. May reduce the natriuretic effects of furosemide or thiazide diuretics. Reduced renal lithium clearance and elevated plasma lithium levels. May enhance anticoagulant effect of warfarin.

Food Interaction

  • Avoid alcohol.
  • Take with food.

Volume of Distribution

  • 1.06 L/kg [Normal Healthy Adults (18-45 yr)]

Elimination Route

Johnstal is rapidly absorbed after oral administration.

Half Life

2 hours

Clearance

  • Oral cl=21.23 L/hr [Healthy adults (18-45 yrs)]

Elimination Route

The fecal route of elimination accounts for up to 20% of the dose, mainly in the form of unconjugated 3-carboxymefenamic acid.3 The elimination half-life of mefenamic acid is approximately two hours. Johnstal, its metabolites and conjugates are primarily excreted by the kidneys. Both renal and hepatic excretion are significant pathways of elimination.

Pregnancy & Breastfeeding use

Pregnancy: In late pregnancy, as with other NSAIDs, Johnstal should be avoided because it may cause premature closure of the ductus arteriosus. In general there are no adequate and well controlled studies in pregnant women. Johnstal should be used during pregnancy only if the potential benefit justifies the potential risk to the foetus. Rated as Pregnancy Category C.

Lactation: Trace amounts of Johnstal may be present in breast milk. Taking into account the importance of the drug to the mother , decision should be made whether to discontinue nursing or to discontinue the drug.

Contraindication

Johnstal is contraindicated in patients with known hypersensitivity to Me Johnstal acid. Johnstal should not be given to patients who have experienced asthma, urticaria, or allergic type reactions after taking aspirin or other NSAIDs. Rarely fatal, anaphylactic like reactions to NSAIDs have been reported in such patients. Johnstal is contraindicated in patients with active ulceration or chronic inflammation of upper gastrointestinal tract and should not be used in patients with preexisting renal disease.

Acute Overdose

Symptoms: Headache, nausea, vomiting, epigastric pain, GI bleeding. Rarely, diarrhoea, disorientation, excitation, coma, drowsiness, tinnitus, fainting, and occasionally convulsions.

Management: Symptomatic and supportive treatment. In acute overdosage, empty the stomach immediately by inducing emesis or by gastric lavage followed by admin of activated charcoal.

Storage Condition

Store between 20-25° C.

Innovators Monograph

You find simplified version here Johnstal

Johnstal contains Mefenamic acid see full prescribing information from innovator Johnstal Monograph, Johnstal MSDS, Johnstal FDA label

FAQ

What is Johnstal used for?

Johnstal is used short-term to treat mild to moderate pain in adults and children who are at least 14 years old.

How safe is Johnstal?

Johnstal may increase your risk of heart problems, including heart attack, stroke, heart failure, or blood clot. These conditions can be fatal. Your risk may increase if you already have heart disease or have taken the medication for a long period of time or at high doses.

How does Johnstal work?

Johnstal works by stopping the body's production of a substance that causes pain, fever, and inflammation.

What are the common side effects of Johnstal?

Common side effects of Johnstal are include:

  • diarrhea.
  • constipation.
  • gas or bloating.
  • headache.
  • dizziness.
  • nervousness.
  • ringing in the ears

Is Johnstal safe during pregnancy?

Use of Johnstal during pregnancy is not advised unless prescribed by a doctor, especially if you are 30 or more weeks pregnant.

Is Johnstal safe during breastfeeding?

Johnstal passes into breast milk and is not recommended for use while breastfeeding.

Can I drink alcohol with Johnstal?

Do not drink alcohol while taking Johnstal. Alcohol can increase your risk of stomach bleeding caused by Johnstal. Call your doctor at once if you have symptoms of bleeding in your stomach or intestines.

Can I drive after taking Johnstal?

Johnstal Tablets may cause drowsiness, fatigue, dizziness or may affect your vision. If you experience any of these symptoms, you should not drive or operate machinery, or perform any tasks which may require you to be alert.

When should be taken of Johnstal?

Johnstal is usually taken with food every 6 hours as needed for up to 1 week.

Is it safe to take Johnstal?

Johnstal should not be used for longer than 7 days.

How many times can I take Johnstal?

Johnstal take 250 mg every six hours as needed. You shouldn't take Johnstal for longer than three days.

How long does Johnstal take to work?

If you wait until the symptoms have worsened,Johnstal may not work as well. If you are using Johnstal for painful periods, take your first dose as soon as your period starts or pain begins. Usually, you will only need to take it for the first 2 to 3 days of your period.

How long does it take for Johnstal to kick in?

Johnstal takes between 2 - 4 hours to kick in and start easing your period pain. Each 500mg dose of Johnstal kills pain for up to 8 hours, so you may need to take it two or three times a day for all-day relief.

Can I take Johnstal for a long time?

Johnstal should not be used for longer than 7 days. Follow your doctor's dosing instructions very carefully. If you use Johnstal long-term, you may need frequent medical tests.Johnstal can cause unusual results with certain medical tests.

Who should not take Johnstal?

Johnstal can increase your risk of fatal heart attack or stroke. Do not use Johnstal just before or after heart bypass surgery .Johnstal may also cause stomach or intestinal bleeding, which can be fatal.

What happens if I miss a dose on Johnstal?

Take Johnstal as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happen if I take too much Johnstal?

If you take too much If you take too much Johnstal, you may experience: drowsiness, nausea,vomiting.

When can I stop taking Johnstal?

If you experience any of the following symptoms, stop taking Johnstal and call your doctor: stomach pain, heartburn, vomit that is bloody or looks like coffee grounds, blood in the stool, or black and tarry stools.

Can Johnstal affects my heart ?

Johnstal can increase your risk of fatal heart attack or stroke, especially if you use it long term or take high doses, or if you have heart disease.

*** Taking medicines without doctor's advice can cause long-term problems.
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