Table 4 Drugs with Level-1 MDIs with the most clinical significance

Tramadol

42

Concomitant administration of methadone and tramadol may result in withdrawal symptoms; methadone (moderate CYP 2D6 inhibitor) may decrease the metabolism of tramadol

Chlorpromazine

22

The concomitant use of methadone and chlorpromazine may cause additive CNS and respiratory depression

Levofloxacin

16

Levofloxacin may increase the QTc prolonging effects of methadone

Prochlorperazine

12

The concomitant use of methadone and prochlorperazine may cause additive CNS and respiratory depression

Moxifloxacin

6

Moxifloxacin may increase the QTc prolonging effects of methadone

Ciprofloxacin

5

Ciprofloxacin may increase the QTc prolonging effects of methadone

Haloperidol

5

Haloperidol may increase the QTc prolonging effects of methadone

Buprenorphine

1

Concomitant administration of methadone and buprenorphine may result in withdrawal symptoms

Droperidol

1

Droperidol may increase the QTc prolonging effects of methadone

Nalbuphine

1

Concomitant administration of methadone and nalbuphine may result in withdrawal symptoms

Thioridazine

1

The concomitant use of methadone and thioridazine may cause additive CNS and respiratory depression