DINDEVAN Tablet Ref.[9372] Active ingredients: Phenindione

Posology

Adults

Initial loading dose of 200mg, followed on the second day by a dose of 100mg. Dosage must be adjusted from the third day, dependent on the results of the appropriate coagulation tests such as prothrombin time, reported as international normalised ratio (INR).

Note: Concomitant heparin therapy affects the results of INR control tests, and heparin should be discontinued at least 6 hours before the first INR control test is undertaken.

Control tests must be undertaken at regular intervals and the dosage adjusted according to the results of the INR tests.

A maintenance dose of 50-150mg/day is satisfactory in most patients, but a “resistant” patient may need 200mg/day or more.

A “sensitive” patient may need less than 50mg/day.

Method of administration

Oral.

Symptoms of Overdose

As it may take 48-72 hours for the anticoagulant effect to develop fully, the onset of bleeding may be delayed for a few days and patients may remain profoundly anti-coagulated for several days. Spontaneous bruising, haematomas, haematuria, rectal bleeding and haemorrhage into any internal organ may occur.

Management

• The benefit of gastric decontamination is uncertain. If the patient presents within one hour of ingestion of more than 0.25mg/kg or more than the patient’s therapeutic dose, consider activated charcoal (50g for adults).
• Measure the prothrombin time at presentation and sequentially every 24-48 hours after ingestion depending on the initial dose and initial INR.

For patients ON long-term phenindione therapy:

• Monitor INR for at least 48 hours post overdose.
• If there is no active bleeding but the prothrombin time is dangerously prolonged (INR >6.0), give 0.5-1mg vitamin K by slow IV infusion. Further doses may be given as necessary, titrated to INR. Large doses of Vitamin K may completely reverse the effects of phenindione and make it difficult to re-establish anticoagulation.
• If there is active bleeding give fresh frozen plasma and vitamin K 1mg by slow IV infusion. Titrate further treatment according to repeat INR and presence of active bleeding.
• In cases of life threatening haemorrhage use fresh frozen plasma or factor concentrate.
• Monitor INR to determine when to restart normal therapy.

For the patients NOT ON long-term phenindione therapy:

• If the INR remains normal for 24-48 hours and there is no evidence of bleeding, there should be no further monitoring necessary.
• If there is no active bleeding and the patient has ingested more than 0.25mg/kg or the prothrombin time is already significantly prolonged (INR >6.0) give vitamin K₁. The adult dose is 10-20mg orally or by slow iv infusion. Delay oral vitamin K₁ at least 4 hours after any activated charcoal has been given. Daily doses may be necessary until the prothrombin time returns to the normal range.
• In active bleeding give fresh frozen plasma and vitamin K₁ 10-20mg for an adult by slow intravenous injection.
• If life-threatening haemorrhage, use fresh frozen plasma or a factor concentrate.
• Monitor the INR to determine when to stop vitamin K₁.

Shelf life: 18 Months (Unopened).

None.

Polypropylene container with a tamper evident, low density polyethylene cap containing 28, 100 or 500 tablets.

Not all pack sizes may be marketed.

Any unused medicinal product or waste material should be disposed of in accordance with local requirements.