Regional intravenous limb perfusion compared to systemic intravenous administration for marimastat delivery to equine lamellar tissue

Pharmaceutical agents with potential for laminitis prevention have been identified. Many of these, including the MMP inhibitor marimastat, are impractical for systemic administration. This study compared local delivery of marimastat by regional limb perfusion (RLP) to systemic intravenous bolus dosing (SIVB), and established whether RLP results in local lamellar drug delivery. Six adult horses received 0.23 mg/kg of marimastat by RLP followed by 0.23 mg/kg marimastat by SIVB, with a 24‐h washout period. Lamellar ultrafiltration probes sampled lamellar interstitial fluid as lamellar ultrafiltrate (LUF). LUF and plasma marimastat concentrations (LUF_[M] and P_[M], respectively) were measured for 24 h after each treatment. Regional pharmacokinetic parameters were calculated using noncompartmental analyses. The LUF C_max following RLP was 232 [34–457] times that following SIVB. LUF_[M] after RLP were higher than those obtained after SIVB for 18 h (P < 0.03). Median LUF_[M] were > IC₉₀ of equine lamellar MMP‐2 and MMP‐9 for 9 h after tourniquet removal. RLP appeared superior to SIVB for lamellar marimastat delivery (higher LUF C_max,, AUC and T > IC₉₀ of lamellar MMPs). However, frequent dosing is necessary to achieve therapeutic lamellar concentrations. RLP could be used to investigate whether marimastat prevents experimentally induced laminitis. Further refinement of the technique and dosing interval is necessary before clinical application.