Methods for verification of drug levels using dried blood samples
Provided herein are methods for monitoring treatment for multiple sclerosis in a pregnant subject, and determining the efficacy of a treatment for multiple sclerosis in a pregnant subject. These methods include (a) extracting a drug from a dried blood spot (DBS) sample from a pregnant subject after a treatment for multiple sclerosis has been administered to the pregnant subject; (b) performing mass spectrometry on the extracted DBS sample; (c) determining a peak area ratio of the extracted DBS sample to an internal standard; and (d) identifying the administered treatment as being below the internal standard threshold if the plasma concentration of the treatment is less than 1 as compared to the internal standard ratio. Also provided herein are dried blood spot cards, and kits that include a dried blood spot card pre-treated with at least one internal standard.
1 . A method of monitoring treatment for multiple sclerosis in a pregnant subject, the method comprising:
(a) extracting a drug from a dried blood spot (DBS) sample to produce an extracted DBS sample, the DBS sample being from a pregnant subject after a treatment for multiple sclerosis to the pregnant subject has been administered, wherein the DBS sample comprises blood obtained from the pregnant subject and a filter paper pretreated with a first internal standard;
(b) performing mass spectrometry on the extracted DBS sample;
(c) determining a peak area ratio of the drug in the extracted DBS sample to the first internal standard; and
(d) identifying the administered treatment as being below an internal standard threshold when the peak area ratio of the drug in the extracted DBS sample to the first internal standard is less than 1.
2 . The method of claim 1 , wherein the administered treatment is administration of a drug for relapse-remitting multiple sclerosis.
3 . The method of claim 1 , wherein the administered treatment and the drug are teriflunomide.
4 . The method of claim 3 , wherein the peak area ratio of the drug in the extracted DBS sample to the first internal standard being less than 1 indicates that a level of teriflunomide in the pregnant subject is non-toxic to a fetus of the pregnant subject.
5 . The method of claim 3 , wherein the peak area ratio of the drug in the extracted DBS sample to the first internal standard being greater than 1 indicates that a level of a teriflunomide in the pregnant subject is harmful to a fetus of the pregnant subject.
6 . The method of claim 3 , wherein the internal standard threshold is 0.02 mcg/mL of a teriflunomide.
7 . The method of claim 6 , wherein the teriflunomide is [ 2 H 6 ]-Teriflunomide or [ 13 C 2 , 2H 3 ]-Teriflunomide.
8 . The method of claim 1 , wherein the DBS sample is a blood sample obtained from a finger prick, a venipuncture, an arm prick, a calf prick, a thigh prick, or a palm of hand prick.
9 . The method of claim 1 , wherein the peak area ratio of the drug in the extracted DBS sample to the first internal standard relates to a maximal therapeutic efficacy level.
10 . The method of claim 1 , wherein the filter paper is pretreated with a threshold amount of the first internal standard.
11 . The method of claim 1 , wherein the DBS sample comprises blood obtained from the pregnant subject and the filter paper pretreated with (i) the first internal standard and (ii) a second internal standard.
12 . The method of claim 11 , wherein the filter paper is pretreated with a threshold amount of the first internal standard and a threshold amount of the second internal standard.
13 . The method of claim 11 , further comprising determining a peak area ratio of the drug in the extracted DBS sample to the second internal standard.
14 . The method of claim 13 , wherein the peak area ratio of the drug in the extracted DBS sample to the second internal standard relates to a minimal therapeutic efficacy level.
15 . The method of claim 14 , further comprising determining that an amount of the drug in the pregnant subject is within an acceptable range when: (i) the peak area ratio of the drug in the extracted DBS sample to the first internal standard is less than 1 and (ii) the peak area ratio of the drug in the extracted DVS sample to the second internal standard is greater than 1.
16 . The method of claim 15 , wherein the first internal standard is [ 2 H 6 ]-Teriflunomide and the second internal standard is [ 13 C 2 , 2H 3 ]-Teriflunomide.
17 . The method of claim 15 , wherein the first internal standard is [ 13 C 2 , 2H 3 ]-Teriflunomide [ 2 H 6 ]-Teriflunomide and the second internal standard is [ 2 H 6 ]-Teriflunomide.