Drug-drug interactions
Figure 1 shows the number of pDDIs in each category and exposed patients. Interactions with severity scale of D and X were 17.8% of total pDDIs (161 of 904). About 38% of the patients (86 of 227) were exposed to at least one D or X interaction.
Drug combinations, frequency, reliability, mechanism, and applicable recommendations for D and X interactions are shown in table 2 and 3, respectively. Of the total pDDIs with severity scale of D and X, 23.6% were unique drug pairs (the interaction occurred one time) (appendix 1). The most frequent interactions were between lopinavir/ritonavir and commonly used medications metabolized by cytochrome P450 3A4 (CYP3A4) such as atorvastatin and alprazolam in D category and salmeterol/fluticasone and tamsulosin in X category.