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Table 1 Release of MTX and MTX-α peptides from DK226

From: Novel hyaluronic acid–methotrexate conjugate suppresses joint inflammation in the rat knee: efficacy and safety evaluation in two rat arthritis models

Treatment pH Released concentration (ng/mL)
MTX MTX-α-Phe MTX-α-Phe-Phe
% of released MTX % peak area of MTX-α-Phe after 24-h incubation
Synovial tissue homogenate 4.0 8.82 BLQb BLQc 1.2 0e
7.4 BLQa BLQb BLQc 0 100
Synovial fluid 4.0 1.14 2.02 (1.53)d 1.29 (0.783)d 0.5 80.1
7.4 BLQa BLQa BLQa 0 100
  1. DK226 was incubated in rabbit synovial tissue homogenate or synovial fluid at pH 4.0 or pH 7.4 for 24 h at 37 °C. Release of MTX and MTX-α peptides was measured by LC/Q-TOF-MS. MTX-α-Phe was used as a reference compound to assess the metabolic stability, and the percent peak area of intact MTX-α-Phe and MTX released from MTX-α-Phe were monitored by LC-UV
  2. MTX methotrexate, Phe phenylalanine, BLQ below lower limit of quantification
  3. aBLQ (below LLOQ); <1 ng/mL
  4. bBLQ; <5 ng/mL
  5. cBLQ; <10 ng/mL
  6. dMTX-equivalent concentration
  7. ePercent peak area of MTX-α-Phe after 3-h incubation