Fospropofol disodium injection for the sedation of patients undergoing colonoscopy

Medical, Political, and Economic Considerations for the Use of MAC for Endoscopic Sedation: Big Price, Little Justification?

The last few decades of gastrointestinal (GI) endoscopy have seen phenomenal growth. In many aspects, GI endoscopy has led the field of nonsurgical interventional medicine. In many aspects, this growth is facilitated by advancements in sedation-both drugs and techniques. Unfortunately, the topic of GI endoscopy sedation is also mired in many controversies, mainly emanating from the cost of anesthesia providers. While no one debates their role in the majority of advanced endoscopic procedures, the practice of universal propofol sedation in the USA, delivered by anesthesia providers, needs a closer look. In this review, medical, political, and economic considerations of this important topic are discussed in a very frank and honest way. While such ubiquitous propofol use has increased satisfaction of both patients and gastroenterologists, there is little justification. More importantly, going by the evidence, there is even less justification for the mandated anesthesia providers use for such delivery. Unfortunately, the FDA could not be convinced otherwise. The new drug fospropofol met the same fate. Approval of SEDASYS^®, the first computer-assisted personalized sedation system, was a step in the right direction, nevertheless an insufficient step that failed to takeoff. As a result, in spite of years of research and efforts of many august societies, the logjam of balancing cost and justification of propofol sedation has continued. We hope that recent approval of remimazolam, a novel benzodiazepine, and potential approval of oliceridine, a novel short-acting opioid, might be able to contain the cost without compromising the quality of sedation.

The Role of GABA Receptor Agonists in Anesthesia and Sedation

GABA (γ-aminobutyric acid) receptors, of which there are two types, are involved in inhibitory synapses within the central nervous system. The GABA_A receptor (GABAAR) has a central role in modern anesthesia and sedation practice, which is evident from the high proportion of agents that target the GABAAR. Many GABAAR agonists are used in anesthesia practice and sedation, including propofol, etomidate, methohexital, thiopental, isoflurane, sevoflurane, and desflurane. There are advantages and disadvantages to each GABAAR agonist currently in clinical use. With increasing knowledge regarding the pharmacology of GABAAR agonists, however, newer sedative agents have been developed which employ 'soft pharmacology', a term used to describe the pharmacology of agents whereby their chemical configuration allows rapid metabolism into inactive metabolites after the desired therapeutic effect(s) has occurred. These newer 'soft' GABAAR agonists may well approach ideal sedative agents, as they can offer well-controlled, titratable activity and ultrashort action. This review provides an overview of the role that GABAAR agonists currently play in sedation and anesthesia, in addition to discussing the future role of novel GABAAR agonists in anesthesia and sedation.

A randomized open-label phase I pilot study of the safety and efficacy of total intravenous anesthesia with fospropofol for coronary artery bypass graft surgery

OBJECTIVE

To determine safety and efficacy of the water-soluble prodrug fospropofol for anesthesia in cardiac surgery and to compare the pharmacodynamic profiles of fospropofol and propofol.

DESIGN

Pilot study and a prospective, phase I, open-label, single-center, randomized clinical trial.

SETTING

University hospital; single institution.

PARTICIPANTS

Sixteen patients undergoing elective first-time coronary artery bypass surgery.

INTERVENTIONS

Patients were randomized to receive total intravenous anesthesia with fospropofol (n = 8) or propofol (n = 8) combined with alfentanil as total intravenous anesthesia. Bispectral index, arterial blood pressure, and heart rate were recorded continuously, and pulmonary artery catheter measurements were obtained. Plasma concentrations of formate, phosphate, and Ca(2+) were monitored closely. Safety and tolerability were assessed by adverse events, neurologic examinations, clinical laboratory tests, and vital signs.

MEASUREMENTS AND MAIN RESULTS

The total doses of fospropofol and propofol during anesthesia were 11.3±2.5 and 4.4±1.0 mg/kg/h, respectively. According to the achieved bispectral index (BIS) values, fospropofol was as effective as propofol in providing general anesthesia and sedation. There were no clinical signs of formate toxicity in the fospropofol group. The only treatment-related adverse event after administration of fospropofol was a transient burning sensation in the perineal and perianal region during induction of sedation or anesthesia.

CONCLUSIONS

Fospropofol could be used to provide general anesthesia in patients undergoing coronary artery bypass graft surgery. Further larger studies are needed to prove the safety of fospropofol when given to provide general anesthesia for major cardiac surgical procedures.

Perspectives on the role of fospropofol in the monitored anesthesia care setting

Monitored anesthesia care (MAC) is a safe, effective, and appropriate form of anesthesia for many minor surgical procedures. The proliferation of outpatient procedures has heightened interest in MAC sedation agents. Among the most commonly used MAC sedation agents today are benzodiazepines, including midazolam, and propofol. Recently approved in the United States is fospropofol, a prodrug of propofol which hydrolyzes in the body by alkaline phosphatase to liberate propofol. Propofol liberated from fospropofol has unique pharmacological properties, but recently retracted pharmacokinetic (PK) and pharmacodynamic (PD) evaluations make it difficult to formulate clear conclusions with respect to fospropofol's PK/PD properties. In safety and efficacy clinical studies, fospropofol demonstrated dose-dependent sedation with good rates of success at doses of 6.5 mg/kg along with good levels of patient and physician acceptance. Fospropofol has been associated with less pain at injection site than propofol. The most commonly reported side effects with fospropofol are paresthesia and pruritus. Fospropofol is a promising new sedation agent that appears to be well suited for MAC sedation, but further studies are needed to better understand its PK/PD properties as well its appropriate clinical role in outpatient procedures.

Safety evaluation of fospropofol for sedation during minor surgical procedures

STUDY OBJECTIVE

To evaluate the safety of intravenous (IV) fospropofol when used to provide minimal to moderate sedation in patients undergoing minor surgical procedures.

DESIGN

Phase 3, open-label, single-arm study.

SETTING

Multi-center.

PATIENTS

123 ASA physical status I, II, III, and IV patients, aged>or=18 years.

INTERVENTIONS

Patients were pretreated with fentanyl 50 microg before receiving an initial dose of IV fospropofol 6.5 mg/kg. Patients could receive up to 5 supplemental doses of fospropofol 1.63 mg/kg to reach a Modified Observer's Assessment of Alertness/Sedation (MOAA/S) score<or=4 to allow the start of the procedure and to maintain adequate sedation levels during the procedure.

MEASUREMENTS

Study endpoints included measures of sedation depth, requirement for supplemental sedative doses, use of alternative sedatives, and the frequency and nature of treatment-emergent and sedative-related adverse events.

MAIN RESULTS

A mean of 2.4 supplemental doses of fospropofol was administered, and in 60% of patients, two or fewer supplemental doses of fospropofol were sufficient to initiate and complete the procedure. Alternative sedative medication was administered in 6 of 123 patients (4.9%). Mean (SD) MOAA/S score during the procedure was 3.8 (0.5). Sixty-one percent (61%) of patients had a MOAA/S score of 5 (fully alert) within two minutes after the end of the procedure. Few patients (7 of 123; 5.7%) had MOAA/S scores of 0 to 1 (deep sedation) during the procedure, and all 7 were either ASA physical status I (n=1) or II (n=6). The most common treatment-related adverse events (TRAEs) were self-limited: paresthesias (62.6%) and pruritus (27.6%). Five patients experienced sedation-related adverse events, including hypotension (n=4), bradycardia (concurrently with hypotension and managed with atropine; n=1), or hypoxemia (less than one min and managed with chin lift and verbal stimulation; n=1). Twenty patients with previous or existing hepatic disease (ranging from minimal to severe) and 5 patients with severe renal impairment had adverse events similar to the overall population. No deaths were reported, and no patient discontinued the study due to adverse events.

CONCLUSION

An initial dose of IV fospropofol 6.5 mg/kg with supplemental doses was safe and well-tolerated as moderate sedation for use in minor surgical procedures.

Fospropofol

Fospropofol (fospropofol disodium), a sedative/hypnotic agent, is a water-soluble prodrug of propofol, metabolized in vivo to produce liberated propofol (producing the sedative effect), phosphate and formaldehyde. Intravenous fospropofol 6.5 mg/kg was significantly more effective than fospropofol 2.0 mg/kg (a placebo surrogate) as sedation in patients undergoing colonoscopy or flexible bronchoscopy, with regard to the primary endpoint of sedation success rate in randomized, double-blind, phase III trials. In patients undergoing colonoscopy, the sedation success rate was >3-fold higher among fospropofol 6.5 mg/kg (n = 158) than fospropofol 2.0 mg/kg recipients (n = 102). Similar results were observed in patients undergoing flexible bronchoscopy; the sedation success rate was >3-fold greater among fospropofol 6.5 mg/kg (n = 150) than among fospropofol 2.0 mg/kg recipients (n = 102). Fospropofol was generally well tolerated in clinical trials. Adverse events were mostly of mild to moderate severity, and were transient and self-limiting. Patients undergoing flexible bronchoscopy appeared to have a higher rate of sedation-related adverse events requiring airway assistance than did those undergoing colonoscopy or minor procedures.

Fospropofol disodium, a water-soluble prodrug of the intravenous anesthetic propofol (2,6-diisopropylphenol)

BACKGROUND

Today, propofol or 2,6-diisopropylphenol is the anesthetic mainly used for monitored anesthetic care sedation and during intravenous anesthesia. The formulation, a lipid macroemulsion, shows several disadvantages. Therefore, during the past years considerable scientific effort has been undertaken to find either a better formulation or a prodrug of propofol. Fospropofol is the first propofol prodrug that has been intensively studied in man. It has been licensed in 2008 by the FDA for monitored anesthetic care sedation.

OBJECTIVES AND METHODS

This review describes first published study results of fospropofol with regard to its pharmacokinetics/pharmacodynamics, drug safety, tolerability and drug side effects. Using a Medline search all published articles and abstracts containing the words fospropofol or GPI 15715 were included.

RESULTS AND CONCLUSION

As the impact of an errorness drug assay for propofol liberated from fospropofol is not exactly defined, no clear conclusions can be drawn from the first published pharmacokinetic/pharmacodynamic studies. Fospropofol was well tolerated in the first two clinical studies and no serious side effects were reported. After characterization of the true pharmacokinetic/pharmacodynamics profile, fospropofol, an aqueous solution, has the potential to favorably compare with benzodiazepines for procedural sedation and also may be used for long-term sedation and intravenous anesthesia.

Fospropofol: a new sedative-hypnotic agent for monitored anesthesia care

OBJECTIVE

To summarize the published clinical data on fospropofol, critically review the safety and efficacy information, and provide pertinent information for formulary review.

DATA SOURCES

Data were collected from searches of MEDLINE (1966-June 30, 2009), EMBASE (1974-June 30, 2009), bibliographies of manuscripts, and www.fda.gov. Key search terms included fospropofol, Lusedra, Aquavan, sedative-hypnotic, and monitored anesthesia care.

STUDY SELECTION AND DATA EXTRACTION

All Phase 1, Phase 2, and Phase 3 clinical trials studying the safety and efficacy of fospropofol were reviewed.

DATA SYNTHESIS

Fospropofol is a water-soluble prodrug of propofol, a potent sedative-hypnotic agent. Propofol is highly lipophilic and is formulated in lipid-containing solvents, which have known disadvantages, including pain on injection, narrow therapeutic window with the potential to cause deep sedation, high lipid intake during long-term sedation, and risk of infection resulting from bacterial contamination. Due to its water solubility, fospropofol eliminates some of the known lipid emulsion-associated disadvantages of propofol and provides a more predictable peak onset of activity and more gradual recovery to a full state of consciousness. The pharmacokinetic and pharmacodynamic profiles of fospropofol make it an attractive agent for sedation for procedures of short duration. Unfortunately, the number of patients studied has been relatively small and the amount of safety data is limited. Of concern are reports of hypoxemia and hypotension; these reports are limited in number, but the episodes are serious and may require acute intervention. Although fospropofol holds promise for procedural sedation, due to limited safety data, the Food and Drug Administration has limited approval of fospropofol to monitored anesthesia care in patients undergoing diagnostic or therapeutic procedures.

CONCLUSIONS

Fospropofol is a viable addition to the class of sedative-hypnotic agents due to the minimization of unwanted adverse effects of propofol and maintenance of a favorable pharmacokinetic profile facilitating sedation, anxiolysis, and rapid recovery. However, there are limited safety data to justify its use without the presence of dedicated anesthesia personnel.