We recruited and screened thirty-two healthy volunteers who were randomly allocated equally into two groups : an NSAID control group , who received 75 mg slow-release diclofenac , twice daily for 14 d ; and an NSAID-muscovite group , who received 3 g of muscovite in addition to the 75 mg of slow-release diclofenac , twice daily for 14 d. For gastroprotection , both groups were administered 20 mg/d of the proton pump inhibitor omeprazole .