Diclofenac, a phenylacetic acid derivative is a prototypical NSAID. It has potent anti-inflammatory, analgesic and antipyretic actions. It reversibly inhibits the enzyme, cyclooxygenase, thus resulting in reduced synthesis of prostaglandin precursors.
Misoprostol is a synthetic prostaglandin E1 analogue. It protects the GI mucosa by inhibiting basal, stimulated and nocturnal acid secretion and by reducing the volume of gastric secretions and increasing bicarbonate and mucus secretion. It also induces contractions of smooth muscle fibres of the myometrium and relaxation of the cervix uteri.