As recorded in our study, both L. casei Shirota and L. casei LC01 were inhibited by non-steroidal anti-inflammatory drugs (NSAID) containing diclofenac potassium or ibuprofen arginine as well as by the two antibiotics tested. In addition, L. casei Shirota was affected by selective serotonin reuptake inhibitors (SSRI) antidepressant containing paroxetine and antiarrhythmic medication containing amiodarone. L. casei LC01 was inhbited by hypolipidemic medication containing simvastatin. 

The correct evaluation of possible interactions between medicaments and probiotic bacteria depends on the determination of MIC of these medicaments. The MIC for Spidufen, an anti-inflamatory and anti-rheumatic drug, was 40 mg/mL for both L. casei Shirota and L. casei LC01. Considering that the daily dose for this medicament is 600 mg, the MIC value associated to the volume of the human GIT indicate that the recommended daily dose will hardly affect the survival of the probiotic bacteria. More important are the medicaments for treatment of chronic diseases, such as Zocor, an anti-lipemic drug used for the reduction of the body lipids, Atlansil, an anti-arrhytmic drug normally used in long course treatments and Arotin, a drug from the group of the anti-depressants with neuroleptic effect, also used in long-term treatments, which presented MIC of 1.0 mg/ml, 1.25 mg/ml and 1.0 mg/ml, respectively. Due to their long-term application, they can accumulate in the gastrointestinal tract and affect the viability of the probiotic cultures.