How Was the Lorazepam Milk-to-Plasma Ratio Estimated?
A lorazepam case report estimated a milk-to-plasma ratio of 0.16 after a single dose. To interpret that number, look at where each half of the calculation came from.
One side came from the participant
Researchers collected six milk samples and two maternal plasma samples over 24 hours. They used the milk measurements to estimate the area under the milk concentration–time curve. The reported milk concentrations, 0.65 to 2.10 ng/mL, were below the method’s validated lower limit of quantification, which limits confidence in the exact values.
The plasma curve came from published data
The authors estimated 24-hour plasma exposure from published concentration–time profiles adjusted for dose. Dividing the measured milk curve estimate by that literature-based plasma estimate produced the ratio. The result depends on how closely the published profiles approximate this participant’s plasma exposure.
Source
Shitreh et al., Frontiers in Pharmacology (full text) · DOI
