ABSTRACT
The present work was done to study the interaction between clonidine. an antihypertensive drug which has a prostaglandin synthesis stimulating effect and tiaprofenic acid an analgesic anti-inflammatory drug which has prostaglandin synthesis inhibiting effect.It was found that tiaprofenic acid significantly decreased the hypotensive effect of clonidine in dogs.On the other hand, it was found that clonidine decreased the analgesic and anti-inflammatory effects of tiaprofenic acid significantly in arthritic rats, when the analgesemeter and rats paw edema meter were used for assessment of the analgesic and anti inflammatory effect. Accordingly, simultaneous administration of tiaprofenic acid and clonidine is not recommended because each drug may antagonise some beneficial effects of the other drug