Question

Case study 3

A 63-year-old man had been taking warfarin continuously for the previous five years following a second proximal deep vein thrombosis. His warfarin dose had been 3.5mg daily, which had not altered for the past nine months. His INR results in the anticoagulant clinic during this time had varied from 2.3 to 2.6. His target INR was 2.5.

He had also been taking diclofenac SR 100mg daily for rheumatoid arthritis for the previous two years, which had caused him some dyspepsia. His anti-inflammatory medication was changed to rofecoxib 12.5mg daily, which he had been taking for two weeks prior to his clinic appointment. At the clinic his INR was 7.7 and, apart from starting rofecoxib, nothing else had changed with respect to his medication or lifestyle. He was advised to stop taking warfarin for the next three days, then to restart at a lower dose (2.5mg daily). He was also advised to stop taking the rofecoxib, and to return to his general practitioner to discuss further management of his arthritis. When he attended the anticoagulant clinic one week later, his INR had fallen to 3.2 and his GP had restarted him on diclofenac.

Write about the medication. What it treats. Give some explanation/diagnosis and drug interactions.

Answer 1

Deep vein thrombosis(DVT) is a condition wherein a blood clot is present, commonly in the veins of lower extremities. The aim of the treatment of DVT is to prevent its complications like Pulmonary Embolism(PE) , Recurrent DVT, Post thrombotic syndrome(PTS) and death.This condition is treated with Anticoagulants or Blood thinners.

Anticoagulants: These are used to prevention of new clots and preventing the growth of existing clots especially in those patients recovering from MI, Heart attack,those at high risk for DVT.

Warfarin is works as anticoagulant to treat this condition. The Therapeutic range of INR(international normalised ratio) is 2.5-3.5. To bring INR to normal range, warfarin should given to the patient.

Rheumatoid arthritis is chronic inflammatory disease which affects many joints and body's immune system attack's its own tissues like joints. Diclofenac is NSAID drug  used to treat light pain and relax from pain and results in  treating the arthritis condition.

The drug Rofecoxib is the selective COX-2 inhibitirs used to treat arthritis.

The most common side effect of taking Diclofenac is indigestion (DYSPEPSIA), heart burn,etc.

DRUG INTERACTIONS:

Diclofenac should not be given to those having problems with blood clotting. this medication should be avoided because using diclofenac and warfarin together may cause you to bleed more easily.

while taking Warfarin, if INR value increases then stop taking that drug to bring INR to therapeutic range to avoid risk of bleeding. vitamin.K is the antidote for warfarin and increasing vitamin K amount in the body can enhances clotting and decreases the effect of warfarin in the body.

More saturation of plasma protiens or metabolic enzymes with warfarin might be the cause of more frequent drug interactions.

Rofecoxib drug can be used in patients who do not require platelet inhibition. However, taking Rofecoxib along with Warfarin can cause slight increase in INR value leads to haemorrhagic condition where bleeding happens easily.

Bleeding can be prevented with early detection of INR increase. Interaction between NSAIDs and warfarin , Celecoxib or naproxen may be recommended as first line NSAIDs in Warfarin users.