Celebrex® (celecoxib) is a nonsteroidal anti-inflammatory drug (NSAID) that is u

Question

Celebrex® (celecoxib) is a nonsteroidal anti-inflammatory drug (NSAID) that is used to treat the pain and inflammation of osteoarthritis and rheumatoid arthritis. Pure celecoxib (mp 157 – 159 oC) is a pale yellow solid material at room temperature.

a) In principle is a melting point of 150 – 154 oC consistent with a sample of celecoxib contaminated with a small quantity of aspirin? Pure aspirin (also known as acetylsalicylic acid (ASA)) has a melting point of 135 oC. Yes or No?

b) In principle is a melting point of 96 – 97 oC consistent with a sample of celecoxib contaminated with a small quantity of aspirin? Yes or No?

Explanation / Answer

The melting point of Celecoxib drug is 157-159 oC.

With the contamination of the drug with Aspirin whose melting point is 135 oC, the consistency in the melting point of the pure drug is changed. Addition of impurity always depresses the melting point but not rises.

When the pure drug is contaminated with the aspirin, aspirin acts as an impurity which disturbs the regular arrangement of the particles in the drug and also disrupts the bonding. Because of these disturbances, lesser energy is required to break the bonds and hence the melting point decreases slightly to a small extent. Hence, the melting point of 150-154 oC is consistent.

The melting point of the contaminated drug depresses to a small extent but not to a great extent. Hence, the melting point of 96-97 oC is not consistent.

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