P&T News: April 2002
Linda M. Schrand, Pharm.D., Elizabeth A. Beltz, Pharm.D.
Internally Peer Reviewed by: Thomas Gross, M.D.,
Assistant Professor, Division of Pulmonary Diseases, Critical Care
and Occupational Medicine, Department of Internam Medicine
Severe sepsis is defined as sepsis associated with acute organ dysfunction. It is estimated that severe sepsis occurs in 750,000 patients each year in the United States with an estimated survival rate of only 50 to 70%.3
The release of inflammatory mediators described above contributes to vasodilatory changes. Initially, the patient may be able to compensate by increasing the heart rate and cardiac output, but as the sepsis progresses the patient is no longer able to compensate adequately and hypotension and/or hypoperfusion may persist despite the administration of intravenous fluids. This is the definition of septic shock. Patients who do not respond to fluids and inotropic therapy may progress to multiple organ dysfunction (MODS) and, in the most severe cases, death.4
The pathophysiology of sepsis is quite complex, involving cytokines, inflammation, and coagulation. The cascade is believed to be initiated by the release of toxins into circulation. These toxins stimulate the release of inflammatory mediators that serve to activate the host cellular defenses. Cytokines, such as tumor necrosis factor-alpha (TNF-alfa), interleukins, and inflammatory prostaglandins, are released by white blood cells. An anti-inflammatory response is also triggered, but patients who develop SIRS and sepsis are thought to have an excess of inflammatory mediators that overwhelm this response.5
The inflammatory mediators stimulate the release of tissue factor, which leads to activation of the extrinsic coagulation cascade. This generates thrombin and fibrin. Plasminogen activator inhibitor (PAI-1), another component of the cascade, inhibits fibrinolysis, contributing to microvascular thrombosis. This may ultimately lead to diffuse endovascular injury, multiorgan dysfunction, and death. Uncontrolled systemic coagulation is prevented by the activation of natural anticoagulants such as activated protein C (APC), tissue factor pathway inhibitor (TFPI), and antithrombin. APC inhibits thrombosis and inflammation and promotes fibrinolysis. Its precursor, protein C, is activated by thrombin coupled to thrombomodulin. In a septic patient, this conversion may be impaired because of down-regulation of thrombomodulin by inflammatory cytokines. The combination of decreased activation of protein C and the rapid consumption of APC in the septic patient contributes to microvascular coagulation.5,6
Because of the high mortality associated with sepsis, a great deal of research has been performed to try to identify treatment strategies to improve sepsis outcomes. A study by Bone et al compared methylprednisolone to placebo in 382 sepsis patients who had been in shock no more than 2 hours.7 They found no difference in prevention or reversal of shock, and mortality was actually higher in the methylprednisolone group (30%) versus the placebo group (25%) (p = 0.06). This increased mortality was felt to be due to secondary infections.
Ziegler et al published a study comparing a monoclonal IgM antibody (HA-1A) to endotoxin versus placebo.8 Endotoxin is a by-product of gram-negative bacteria. Initially the results looked promising, as the mortality was 30% in the HA-1A group and 49% in the placebo group for patients with a documented gram-negative infection. However, only 37% of the patients in the study had a documented gram-negative infection, and when the data were analyzed for ALL patients, the mortality was 39% for the HA-1A group and 43% for the placebo group.
Similar studies looking at other immunomodulatory agents such as anti-TNF-alfa monoclonal antibodies have been similarly disappointing in their failure to show an improvement in mortality of sepsis.9 Antithrombin III has also been studied with unproven results.9 Other types of agents studied with poor results include ibuprofen, prostaglandin E1, and acetylcysteine.9 The effect of administering TFPI in septic patients is currently in Phase III trials.
Drotrecogin Alfa (Activated)
Indication for Use
In November 2001, drotrecogin alfa (activated), a recombinant
human activated protein C, was approved by the FDA. Drotrecogin alfa
(activated) is indicated for the reduction of mortality in adult
patients with severe sepsis (sepsis associated with acute organ
dysfunction) who have a high risk of death (e.g., as determined by
APACHE II). It is the first drug available for the treatment of
sepsis.
The PROWESS Study
The Recombinant Human Activated Protein C Worldwide Evaluation in
Severe Sepsis (PROWESS) Study is the only published Phase III study
that has evaluated the efficacy and safety of recombinant human
activated protein C [drotrecogin alfa (activated); Xigris®
Eli Lilly] in patients with severe sepsis.6 The
PROWESS Study was a multi-national, randomized, double-blind,
placebo-controlled trial that evaluated whether drotrecogin alfa
(activated) would reduce mortality at 28 days in patients with severe
sepsis while at the same time having an acceptable safety profile.
Patients >18 years of age were considered eligible for inclusion in the study if they had a known or suspected infection as evidenced by one or more of the following: white cells in a normally sterile body fluid; perforated viscus; radiographic evidence of pneumonia in association with the production of purulent sputum; or a syndrome associated with a high risk of infection. In addition, patients had to have three or more signs of systemic inflammation and at least one sepsis-induced organ dysfunction (Table 1) that occurred within the last 24 hours. The exclusion criteria were extensive and included patients at an increased risk for bleeding and patients with co-morbid conditions with an expected survival of less than 28 days.
Patients were randomized to receive intravenous therapy with either drotrecogin alfa (activated) at a dose of 24 mcg/kg/hour or placebo (0.9% normal saline with or without 0.1% human albumin) for a total of 96 hours. Other aspects of critical care were not standardized during the study (e.g., use of antibiotics, fluids, vasopressors, or ventilatory support).
Efficacy
The trial was designed to enroll 2280 patients, but enrollment
was suspended after the second interim analysis of data because the
mortality rate between the two groups exceeded the a priori guideline
for stopping the study. A total of 1690 patients were enrolled in the
study; 850 in the drotrecogin alfa (activated) arm and 840 in the
placebo arm. Of these 1690 patients who met the inclusion/exclusion
criteria, approximately 75% had 2 or more organ failures at the time
of enrollment. During the 96-hour infusion, 8.2% of the patients
receiving placebo and 6.4% of the patients receiving drotrecogin alfa
(activated) died. At the endpoint of 28 days after the start of the
infusion, 30.8% of the patients receiving placebo and 24.7% of those
receiving drotrecogin alfa (activated) had died. The absolute
reduction in the risk of death was 6.1%. The relative risk reduction
was 19.4% with drotrecogin alfa (activated) as compared to placebo.
Based on these results, the number needed-to-treat to avoid one death
is approximately 16.
In a subgroup analysis of patients based on APACHE II quartile, a higher rate of mortality was noted in the first APACHE II quartile in the drotrecogin alfa (activated) group as compared to placebo. The relative risk for patients in the first quartile was 1.3 (95% confidence interval of 0.77 to 2.02) as compared to 0.87 (0.63 to 1.22), 0.66 (0.48 to 0.91), and 0.78 (0.65 to 0.97) in the second, third, and fourth quartiles, respectively.10 This demonstrates that those patients in the third and fourth quartiles (scores of 25 to 53) received the most benefit from the drotrecogin alfa (activated) therapy. See Table 2 (pdf file) for information on calculating the APACHE II score or visit http://knowledge.emedicine.com/etools/index.htm to electronically calculate the score for a patient. (This information can also be downloaded onto a PDA at http://pda.tucows.com/palm/preview/159877.html.)
|
Table 1. Definitions of Systemic Inflammatory Response and Sepsis-Induced Organ Dysfunction |
|
Systemic response is defined as the presence of 3 or more of the following criteria within the last 24 hours. These criteria must be attributable to the onset of sepsis and not to an underlying disease process or to the effects of concomitant therapy.
Sepsis-induced organ or system failure is defined as at least one of the following occurring within the last 24 hours. These criteria must be attributable to the onset of sepsis and not to an underlying disease process or to the effects of concomitant therapy.
|
Safety
The most serious adverse event during the study was bleeding. The
incidence of serious bleeding events was higher in the drotrecogin
alfa (activated) group than in the placebo group; 3.5% (n=30) versus
2% (n=17), respectively.6 There were four deaths from
bleeding in the active treatment group thought to be possibly related
to the drug; the deaths were associated with two cases of cerebral
hemorrhage, one cerebral edema, one pulmonary hemorrhage, and one
aortic disruption.10 Two-thirds of the bleeds in the
drotrecogin alfa activated group occurred during the 96-hour infusion
period, whereas two-thirds of the serious bleeds in the placebo group
occurred in the 28 days after the start of the infusion.10
The majority of the patients who experienced bleeding complications
had an identifiable predisposition to bleeding, such as
gastrointestinal ulceration, an activated partial-thromboplastin time
(APTT) of >120 seconds, an INR >3, a platelet count <
30,000/mm3, traumatic injury of a blood vessel, or
traumatic injury of a highly vascular organ.6 It is,
therefore, prudent to obtain a coagulation profile (APTT, INR, and
platelet count) prior to initiating therapy with this drug.
Adverse events that were noted with a slightly higher frequency in the drotrecogin alfa (activated) group as compared to placebo include: hypertension (2.6% vs. 0.6%), abnormal healing (1.4% vs. 0.5%), hallucinations (1.1% vs. 0.1%), abscess (3% vs. 1%), and thrombocytopenia (2% vs. 1%).10
Pediatric Use of Drotrecogin Alfa (Activated)
Although no formal efficacy trials have been conducted in
pediatric patients, pharmacokinetic and safety information is
available. Two separate studies have been conducted in this
population; 12 patients were in an open label compassionate use trial
in purpura fulminans and 58 patients were in an open-label
pharmacology/safety study in pediatric sepsis.10 Because
neither study had a control group, no information is available
regarding efficacy in this patient population. The
pharmacology/safety study determined through a dose escalation phase
that 24 mcg/kg/hour was the appropriate dose for pediatric patients.
This study also noted serious bleeding as an adverse effect. Of the
58 infants and children in the study, 3 (5%) experienced serious
bleeding events. All three of the bleeding events occurred during the
96-hour infusion period.10
Dosing
Drotrecogin alfa (activated) should be administered intravenously at
a dose of 24 mcg/kg/hour for a total of 96 hours. No dosage
adjustment is recommended for renal or hepatic insufficiency. The
infusion should be held for 2 hours prior to any invasive procedures.
The infusion should not be restarted until adequate hemostasis has
been achieved. The manufacturer recommends waiting 12 hours following
surgery or a major invasive procedure prior to considering the
completion of the 96-hour infusion. The infusion may be restarted
immediately following uncomplicated or less invasive procedures, if
hemostasis has been achieved.11
Cost of Drotrecogin Alfa (Activated)
The UIHC acquisition price for drotrecogin alfa (activated) is
$210 for a 5 mg vial and $840 for a 20 mg vial. The drug is only
stable for 12 hours once reconstituted and, therefore, to reduce the
potential for waste, it will be supplied in approximately 8 to
10-hour bags from the pharmacy. The approximate cost for a 96-hour
infusion for a 70 kg adult patient is $6300.
Prescribing at UIHC
Due to the risk of bleeding associated with this therapy and the
high cost of the drug, the use of drotrecogin alfa (activated) will
be restricted by the use of a protocol drug order form which must be
completed by an attending physician in the intensive care unit
setting (MICU, SICU, 8JC, PICU, or NICU). Because the drug is not yet
approved for use in pediatric patients, a mini-consent form must also
be completed prior to use in this patient population. Drotrecogin
alfa (activated) will not be dispensed by Pharmacy until the required
prescribing forms are completed.
The protocol drug order forms for adult and pediatric patients list the criteria that need to be met in order to determine which patients will possibly receive benefit from the drug while also protecting the patient from unnecessary bleeding risks (Figure 1, pdf file). These criteria must be considered and the potential benefits must outweigh the risks prior to prescribing.
References
PHARMACY AND THERAPEUTICS SUBCOMMITTEE ACTIONS
DRUGS ADDED TO STOCK
NORELGESTROMIN/ETHINYL ESTRADIOL
Transdermal Patch: 150 mcg/20 mcg
Norelgestromin/ethinyl estradiol (Ortho Evra® - Ortho McNeil) is
a combination product transdermal patch indicated for the prevention
of pregnancy. Patches are replaced weekly for 3 weeks during each
28-day cycle.
PIMECROLIMUS
Topical Cream: 1%
Pimecrolimus topical cream (Elidel® - Novartis) is a topical
non-steroidal immunosuppressant that is indicated for short-term and
intermittent long-term therapy in the treatment of mild-to-moderate
atopic dermatitis in patients > 2 years of age for whom the use of
conventional therapies is contraindicated or who are not responsive
to or are intolerant of conventional therapies.
DEXTRANOMER/HYALURONIC ACID COPOLYMER
Syringe: 1 ml
This combination product (Deflux®) is indicated for treatment of
children with vesicoureteral reflex (VUR) grades II-IV.
Available as a kit containing two 1 ml syringes and two specialized needles for administration.
ADDITIONAL ACTIONS
OLANZAPINE TABLET
A 15 mg and a 20 mg tablet (Zyprexa®) have been added to
stock.
Note: Prescribing is restricted to the Departments of Neurology and
Psychiatry.
Note: The cost following each brief monograph is the UIHC inpatient
acquisition cost.
DRUGS DELETED FROM STOCK
ZINC OXIDE PASTE
Discontinued by all manufacturers. Zinc oxide ointment is available.