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Absorptive Kinetics of Transdermal Fentanyl. Robert Leonard, PharmD candidate University of Florida College of Pharmacy. Overview. Rationale Barriers TTS-fentanyl Pharmacokinetics Studies of pharmacokinetic variability. Rationale. Continuous infusion Noninvasive nature
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Absorptive Kinetics of Transdermal Fentanyl Robert Leonard, PharmD candidate University of Florida College of Pharmacy
Overview • Rationale • Barriers • TTS-fentanyl • Pharmacokinetics • Studies of pharmacokinetic variability
Rationale • Continuous infusion • Noninvasive nature • Special populations • Protracted vomiting • Dysphagia • Less frequent dosing
Barriers • Epidermal microflora • Stratum corneum • Subcutaneous vasculature • Physicochemical properties • MW • Lipophilicity
Kinetics • Absorption • F = 0.92 • Protein binding = 79 - 97% • Tmax = 35 hours • Distribution • Vd = 3 – 8 L/kg • Metabolism • CYP3A4 • Major: norfentanyl • Minor: hydroxyfentanyl, hydroxynorfentanyl, despropionylfentanyl
Kinetics • Elimination • Cl = 34.2 – 52.8L/hr • T1/2 = 17hrs (after removal)
Study • Solassol I, Caumette L, Bressolle F, et al. “Inter- and intra-individual variation in transdermal fentanyl absorption in cancer pain patients.” Oncology Reports 14:1029-1036, 2005.
Absorption Kinetics 125 mcg/hr 175 mcg/hr 100 mcg/hr
Results • Significant findings (P < 0.05) • Age: <65, 65-75, >75 • P = 0.030 • Primary cancer location: head and neck, GI, GU, Lung, Brest, others • P = 0.006 • Findings approaching significance (P ≤ 0.06) • Occlusive bandage: yes, no • P = 0.060 • Temperature: <38, 38-40, >40 • P = 0.051
Limitations • Indirect assay
Study • Ashburn MA, Ogden LL, Zhang J, et al. “The pharmacokinetics of transdermal fentanyl delivered with and without controlled heat.” The Journal of Pain 4: 291-297, 2003.
Clinical Pearls • Avoid cutting patches. • Avoid occlusive bandages. • Avoid heat. • Dose according to patient response. • Sustained release after removal.
References Ashburn MA, Ogden LL, Zhang J, et al. “The pharmacokinetics of transdermal fentanyl delivered with and without controlled heat.” The Journal of Pain 4: 291-297, 2003. Grond S, Radbruch L, Lehmann K. “Clinical pharmacokinetics of transdermal opioids: Focus on transdermal fentanyl.” Clinical Pharmacokinetics 38: 59-89, 2000. Muijsers RB, Wagstaff AJ. “Transdermal fentanyl: An updated review of its pharmacological properties and therapeutic efficacy in chronic cancer pain control.” Drugs 61:2289-2307, 2001. Solassol I, Caumette L, Bressolle F, et al. “Inter- and intra-individual variation in transdermal fentanyl absorption in cancer pain patients.” Oncology Reports 14:1029-1036, 2005.