Analytical Sciences

In vitro and in vivo Methods to Measure the Ceftriaxone Distribution into the Rat Tail Intervertebral Disc

Chia-Chun LIN,*1,*2 Yu-Tse WU,*2 Jiin-Cherng YEN,*1 Chang-Jung CHIANG,*3,*4 Yang-Hwei TSUANG,*4 and Tung-Hu TSAI*2,*5

*1 Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan
*2 Institute of Traditional Medicine, National Yang-Ming University, Taipei, Taiwan
*3 Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan
*4 Department of Orthopedic Surgery, Taipei City Hospital, Taipei, Taiwan
*5 Department of Education and Research, Taipei City Hospital, Taipei, Taiwan

To characterize the pathway of ceftriaxone penetration into intervertebral discs, rat-tail discs were collected and immersed in a ceftriaxone solution for an in vitro study. For this in vivo experiment, plasma and tail discs were collected 30 min after ceftriaxone administration (463.2 mg/kg, equal to 500 mg/kg disodium salt, iv). The ceftriaxone levels in the plasma and discs were determined with HPLC by a reversed-phase C18 column and a mobile phase of methanol and a 10 mM K₂HPO₄ solution (pH 6.7) (21:79, v/v). The results indicate that ceftriaxone was undetectable by the in vitro model. The concentrations of ceftriaxone in plasma and in intervertebral discs were 147.4 ± 21.2 and 4.0 ± 1.7 μg/mL (as disodium salt), respectively. Our results suggest that a sufficient blood supply is required for the passive diffusion of ceftriaxone into intervertebral discs. The concentration ratio of ceftriaxone in intervertebral disc-to-plasma was about 2.7% at 30 min after ceftriaxone disodium administration (500 mg/kg, iv).

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