During the development process of a new drug, it is crucial to get accurate results on how the drug reacts on the individuals on which it is being tested. Procedures such as drug metabolism (DM) and pharmacokinetic (PK) studies require blood draws. Before the 1960s, the primary method was drawing large volumes of blood using the traditional method (venipuncture). However, with the emergence of dried blood spot (DBS) technique, only a small amount of blood is required in many cases.
Old-school dried blood spotting uses instruments such as DMPK cards. For decades, DMPK cards have been used to take blood samples in areas where resources are limited, in scenarios such as newborn screening, or in normal clinics and hospital labs as an alternative to venipuncture.
Benefits of Using DMPK Cards
Advantages of utilizing DMPK cards include:
It is a quick and convenient process of collecting a sample.
Only a small sample (as little as 10µL) to spot the DMPK card is required.
The technique yields more consistent data.
It is easy to store and transport the samples as they require room temperature.
Obtaining data from the dried sample is a relatively straightforward three-step procedure.
The Big Drawback of Using DMPK Cards
Use of DMPK cards, however, has a limitation known as the hematocrit bias. The volume percentage of red blood cells in a blood sample (blood hematocrit) has an inverse relationship with how well the blood spreads on the paper used in DMPK cards. Normally, blood with a high hematocrit level results in a smaller dried blood sample while one with a lower level results in a larger-size blood sample. However, with the use of DMPK cards, it may be difficult to infer reliable results considering the quality of the paper used, punching, and even uneven blood spread that may result to disproportionate results.
With the Mitra® device, however, an alternative to DMPK cards and other old-fashioned DBS technology, it is possible to eliminate hematocrit bias, yielding results comparable to the those from wet blood and at the same time enjoying the benefits of DBS. The Mitra microsampler tip absorbs precisely 20µ of blood with no regard for viscosity into the absorbent tip within seconds. The sample is then dried and the remaining volume delivers accurate hematocrit reading.
For more convenient and economical blood collection, the best solution is the Mitra device.