Welspas

Uses

Spastic conditions of the gastrointestinal tract, irritable bowel syndrome-

• Biliary colics and spastic conditions of the biliary tract: Cholecystolithiasis, cholecystitis, cholangitis.
• Renal colics and spastic conditions of the urogenital tract: Nephrolithiasis, ureterolithiasis, pyelitis, cystitis.
• Spastic conditions of the uterus: Dysmenorrhea, imminent abortion, uterine tetanus.

Mefenamic acid 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.

Welspas is also used to associated treatment for these conditions: Abdominal Pain caused by Gall Stones, Abdominal Pain caused by Kidney Stones, Muscle Spasms, Spastic Pain, Spastic Pain caused by Cystitis, Spastic Pain caused by Funicular Nephritis, Spastic Pain caused by Gallbladder disorders, Spastic Pain caused by Physical Examination, Spastic Pain caused by cholecysitis, Spastic Pain of the Gastrointestinal TractMild pain, Primary Dysmenorrhoea, Gastrointestinal cramps, Moderate Pain

How Welspas works

Drotaverine is a selective inhibitor of phosphodiesterase 4 (PDE4), which is an enzyme responsible for the degradation of cyclic adenosine monophosphate (cAMP). Inhibition of PDE4 leads to elevated levels of cAMP, leading to smooth muscle relaxation. Recent research showed that low levels of cAMP have been associated with brain tumorigenesis, leading to the investigation of PDE4 inhibitors as potential anticancer agents.

Mefenamic acid 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

Welspas dosage

Oral-

• Adults: 1 to 2 tablets, 3 times daily
• Children (over 6 years): 1/2 to 1 tablet, 1-2 times daily.
• Children (1-6 years): 1/4 to 1/2 tablet, 1-2 times daily.

Injection-

• Adults: 1 to 2 ampoules, intramuscularly or subcutaneously, 1-3 times daily.
• For the management of acute stone colics: 1 or 2 ampoules by slow intravenous injection.

As with other NSAIDs, the lowest dose should be sought for each patient. Therefore, after observing the response to initial therapy with Mefenamic acid, 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

The common side effects are headache, dizziness, rhinitis, sinusitis, gastrointestinal upset, nausea, pharyngitis, edema and fatigue.

In patients taking Mefenamic acid 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 LD₅₀ is 540 mg/kg in rats and 350 mg/kg in mice. There is limited information on drotaverine overdose and 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

Caution should be taken for patients suffering from liver and kidney disease.

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 Mefenamic acid is not recommended.

Interaction

May attenuate the action of levodopa. Concurrent use of analgesics, antimuscarinics or benzodiazepines. Additive beneficial effect with concurrent use of analgesics, antimuscarinics or benzodiazepines.

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.

Volume of Distribution

Following oral administration of a single 80 mg dose, the mean volume of distribution was 193 ± 48 L. Following an intravenous dose of 80 mg, the mean volume of distribution was 195 ± 48 L.

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

Elimination Route

Drotaverine is not completely absorbed following oral administration and its bioavailability is highly variable. Following oral administration of a single 80 mg dose, the absolute bioavailability ranged between 24.5 and 91 % with a mean of 58.2 ± 18.2%. Mean C_max was 292 ± 88 ng/mL. Mean AUC was 3251 ± 950 ng*h/mL. Mean T_max was 1.9 ± 0.54 hours.

Mefenamic acid is rapidly absorbed after oral administration.

Half Life

Following oral administration of a single 80 mg dose, the mean half-life was 9.11 ± 1.29 hours. Following an intravenous dose of 80 mg, the mean half-life 9.33 ± 1.02 hours.

2 hours

Clearance

Following oral administration of a single 80 mg dose, the mean renal clearance was 0.59 ± 0.18 mL/min. Following an intravenous dose of 80 mg, the mean renal clearance was 0.73 ± 0.29 mL/min.

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

Elimination Route

Drotaverine is mainly eliminated via hepatic metabolism. About 67% of the drug is found in feces and 20% of the drug was eliminated with urine.

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. Mefenamic acid, its metabolites and conjugates are primarily excreted by the kidneys. Both renal and hepatic excretion are significant pathways of elimination.

Pregnancy & Breastfeeding use

As with most drugs, the use of Drotaverine Hydrochloride should be avoided during pregnancy and lactation unless essential.

Pregnancy: In late pregnancy, as with other NSAIDs, Mefenamic acid 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. Mefenamic acid 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 Mefenamic acid 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

Drotaverine is contraindicated in patients with known hypersensitivity to the products and its constituents.

Mefenamic acid is contraindicated in patients with known hypersensitivity to Me Mefenamic acid acid. Mefenamic acid 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. Mefenamic acid 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

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