Table 1. Opiate Conversions to Morphine Equivalents.

Although there are multiple published opiate conversion algorithms, for the purpose of this study, we chose the conversions used clinically in our NICU. We used the same conversions in all three time epochs to make drug exposure comparable. It is possible that with other conversion metrics the absolute numbers would be different, but the trend would be similar.

Drug	Morphine: Opiate Equivalence Ratio	IV: Oral Conversion Ratio
Morphine	1:1	1:1
Fentanyl*	20:1	Always IV
Hydromorphone	5:1	Always IV
Methadone	10:1	1:1
Diluted Tincture of Opium (DTO)¥	0.4:1	Always Oral

^*Fentanyl conversions derived from Saarenmaa et al¹¹ and Simons et al¹²

^¥DTO conversion is 0.4 mg morphine for every 1 ml DTO