There are data on the interaction with drugs that have similar pharmacological characteristics. Children should not be prescribed medications with Imodium, which have an overwhelming effect on the function of the central nervous system.
Preclinical tests demonstrate that loperamide is a substrate of the P-glycoprotein. With the combined use of loperamide (16 mg) with P-glycoprotein substance inhibitors (such as ritonavir or quinidine), the plasma index of loperamide doubled / tripled. The clinical significance of this interaction in case of using the recommended dosages of loperamide remains unknown.
The combination of loperamide (single dose of 4 mg) with itraconazole, and in addition inhibitor of the element CYP3A4, as well as P-glycoprotein 3-4 times increases the plasma index of loperamide. During the same test, the inhibitor of the CYP2C8 element (gemfibrozil) increased the active drug level by about half.
Combined use with itraconazole, as well as gemfibrozil four times increased the peak plasma index of loperamide, and 13 times the AUC. This increase is not related to the CNS action, determined by psychomotor testing.
A single dose (16 mg) of loperamide coupled with ketoconazole, an inhibitor of the CYP3A4 element, as well as the P-glycoprotein, allows a 5-fold increase in the level of loperamide within the blood plasma. This indicator is not associated with increased pharmacodynamic properties, the determination was made using papillomimetry.
Taking medication in combination with oral desmopressin leads to an increase in the latter's indices inside the plasma (3-fold). Most likely, this is due to a slowdown in the motility of the gastrointestinal tract.
There is an opinion that drugs that have a similar medicinal effect are capable of increasing the properties of loperamide, but drugs that accelerate the passage of food inside the gastrointestinal tract, on the contrary, can weaken its effectiveness.