Ceprotin® is a highly purified plasma-derived concentrate of human protein C zymogen. The product has been developed since 1990 by the pharmaceutical company Immuno Ag, Vienna, Austria, and introduced into clinical trials and international approval by Baxter Healthcare Corp. Today, it is produced by Baxter AG, Vienna. Ceprotin® is produced from frozen human plasma, fulfilling the highest levels of international quality standards, and tested negative for HIV, hepatitis A, B and C virus, and parvovirus B19 by serological and specific polymerase chain reactions. The production process includes several anion exchange chromatography steps, and final purification is performed with immunoadsorption on a murine monoclonal antibody to human protein C. Virus inactivation steps include vapor heating and treatment with polysorbate 80.
Ceprotin® is delivered as a sterile lyophilized powder, bottled in glass vials containing 500 or 1000 international units (IU) of protein C. One IU corresponds to the measured protein C activity in 1 mL of normal human plasma. It is reconstituted with sterile water for injections, the product contains human protein C with a high specific activity (>200 IU/mg protein). The content of activated protein C is negligible. The content of other vitamin K dependent factors is below 1 IU/100 IU protein C. Additionally, 1 vial with 500 IU protein C contains 40 mg human albumin, 44 mg sodium chloride, and 22 mg trisodiumcitrate. Ceprotin® is approved by the European and US authorities for the treatment of severe congenital protein C deficiency, ie, for neonatal purpura fulminans and for patients with coumarin-induced skin necrosis. It can be used in such patients for short-term prophylaxis when surgery is required, during the initiation of coumarin therapy, when coumarin therapy is not sufficient to resolve the symptoms or when coumarin therapy is not feasible for other reasons.
The lyophilized material has a shelf life of at least 2 years when stored at 4 °C. The dissolved concentrate should be injected immediately, the injection rate must not exceed 2 mL/min in adults or 0.2 mL/min in children less then 10 kg weight. An initial dose of 60–80 IU/kg body weight should be useful in most cases of severe congenital protein C deficiency. Plasma protein C activity should be measured before and after injections to determine recovery and half-life. Following doses should be adjusted to obtain post-infusion plasma protein C activity levels of about 1.0 IU/mL during the initial phase. Doses should be repeated every 6 hours during the acute phase of the symptoms, considering the shortened half-life of protein C in such states. Protein C plasma levels should be measured before every infusion, whenever possible, and the Ceprotin® dose should be modified to obtain pre-infusion plasma levels >0.25 IU/mL. After stabilization, protein C measurements can be reduced to twice daily, and Ceprotin® dose or interval can be modified accordingly. Ceprotin® therapy should be continued until skin lesions and coagulopathy have resolved and the patient is stable, and during an overlapping alternative therapy (warfarin) until international normalized ratio (INR) is in the desired range.
Even a subcutaneous application of this substance can be effective as a salvage or maintenance therapy in patients with poor venous access. Experimental data and clinical reports demonstrated the feasibility of Ceprotin® therapy as a continuous infusion. The resolved drug is stable for at least 32 hours at 30 °C in a syringe. Continuous infusion may have advantages in patients with sepsis and purpura fulminans, in whom the biological half-life of protein C is markedly reduced, and plasma protein C levels may drop between the injections of the concentrate. However, the substance is not yet approved for such an application. If the patient is switched to therapy with vitamin K antagonists, protein C replacement should be continued until stable anticoagulation is obtained. Dose modifications in patients with liver or renal dysfunction are not required, but coagulation parameters in such patients should be controlled frequently. No signs of overdosage have been noted until now.
Ceprotin® is identical with the physiological plasmatic protein C zymogen. The intravenous injection of Ceprotin® results in an immediate increase of the protein C concentration in the plasma. As studied in 12 asymptomatic patients with homozygous or double heterozygous protein C deficiency, the administration of 1 IU Ceprotin®/kg body weight resulted in a median increase of plasma protein C activity of 1.4 % (0.014 IU/mL; range 0.005–0.017 IU/mL). The individual half-lives of protein C vary between 4.4 and 15.9 hours (median 10–12 hours). The individual in vivo recovery varied between 20.4% and 83.2% (median 68.5%). In patients with acute thrombosis, with purpura fulminans, sepsis, or disseminated intravascular coagulopathy, the half-life and the recovery were profoundly lower (1.1 and 1.5 hours in 2 newborns with congenital purpura fulminans).
Ceprotin® has an excellent safety profile. No cases of transmission of microorganisms have been observed. Similar to other intravenous protein preparations, allergic or hypersensitive reactions cannot be excluded completely. Ceprotin® may contain trace amounts of heparin. Therefore, in patients with heparin hypersensitivity, allergic reactions or a drop in platelet count (heparin-associated thrombocytopenia) can be observed. When Ceprotin® is used in patients with severe protein C deficiency, the formation of inhibiting alloantibodies cannot be completely excluded (as in severe hemophiliacs treated with factor VIII concentrates), but has not yet been observed. Although Ceprotin® has been used in the treatment of pregnant women with protein C deficiency without any side effects, this has not been studied in controlled trials. No information is available on the possible excretion of Ceprotin® in the milk of lactating mothers. Therefore, the benefits of Ceprotin® in pregnant or breast-feeding women must carefully be balanced against potential risks.
Ceprotin® in congenital protein C deficiency
Coumarin-induced skin necrosis
Several reports on beneficial effects of protein C replacement in patients with coumarin-induced skin necrosis have been published (Schramm et al 1993
; Lewandowski and Zawilska 1994
; Gatti et al 2003
). An analysis of 8 patients, who received in total 78 infusions with 88,476 IU Ceprotin®
, demonstrated that the treatment was safe and effective with an improvement of thrombosis/skin necrosis (unpublished data).
A retrospective surveillance program observed more than 10 years of Ceprotin® use on 79 patients with protein C deficiency of different origins, treated for acute episodes, short-term and long-term prophylaxis, and confirmed the above mentioned safety and efficacy data (unpublished data).
Sepsis and purpura fulminans
Several infections, especially meningococcal or pneumococcal infections in some susceptible patients, may lead to severe coagulopathy and typical skin lesions, resembling the phenotype of neonatal purpura fulminans (). Histological studies of such lesions demonstrated microvascular fibrin deposition and inflammation, resulting from a local breakdown of the protein C system (Shimamura et al 1983
). Early reports from 1995 demonstrated an impressive improvement of such lesions and of coagulopathy after protein C replacement in such cases of infection-induced purpura fulminans (Rivard et al 1995
). Several other publications have presented case series of pediatric and adult patients with severe sepsis, purpura fulminans, and consumption coagulopathy due to meningococcal infections (Gerson et al 1993
; Rivard et al 1995
; Smith et al 1997
; Favier et al 1998
; Kreuz et al 1998
; Rintalaa et al 1998
; Ettingshausen et al 1999
; Clarke et al 2000
; Leclerc et al 2000
; Rintalaa et al 2000
; White et al 2000b
; Fourrier et al 2003
; Vaccarella et al 2003
; Schellongowski et al 2006). All of these reported in part impressive success in these severely ill patients with extremely high bleeding risk. The mortality of the protein C-treated patients in these reports was very low in comparison with the mortality predicted by scoring systems like the Glasgow Meningococcal Prognostic Score. All authors describe very low plasma protein C levels at presentation and a fast resolution of the coagulopathy and normalization of the protein C levels after initiation of protein C zymogen substitution. The signs of purpura fulminans on the skin resolved quickly, as well as organ dysfunction. However, a considerable “publication bias” has to be assumed.
A randomized trial on the use of Ceprotin®
in 40 pediatric patients with severe meningococcal sepsis and septic shock served as a dose-finding study (De Kleijn et al 2003
). Due to the small number of patients no analysis of survival rates could be performed, but it could be shown that the protein C zymogen, infused with the concentrate, was converted to activated protein C in vivo. No side effects occurred. The study demonstrated the safety of Ceprotin®
in a small collective of severely ill patients.
In summary, substitution of protein C in clinical states of acquired pronounced deficiency, mostly presenting as purpura fulminans, consumption coagulopathy, or fulminant thrombosis/organ failure, can cause in part impressive improvement. Although the grade of scientific evidence is low due to the lack of controlled trials, and Ceprotin® is not approved for these indications, the off-label use could be considered in such patients, who otherwise have a high mortality.
(LFB, Les Ulis, France) is a protein C zymogen concentrate, derived from human plasma (Radosevich et al 2003
). Plasma from unpaid blood donors collected after accurate donor selection and donation qualification is used as the source. The purification process is performed on the supernatant after initial cryoprecipitation, and includes three anion exchange chromatography purification steps, the last coupled with heparin-sepharose affinity chromatography. Virus inactivation is performed with solvent/detergent treatment (1% polysorbate and 0.3% tri(n-butyl)phosphate). The process has been shown to effectively inactivate enveloped viruses such as hepatitis B virus, human immunodeficiency virus and hepatitis C virus. This process yields a high-purity product with a specific activity of 215 IU protein C/mg total protein, bottled in vials containing 500 IU protein C. The content of factors II, VII, IX, protein S, and activated protein C is less than 0.01 IU/mL. The total protein concentration is 0.27 g/L. No albumin is added for stabilization.
Animal studies revealed a favorable safety profile: no signs of thrombogenicity were observed, even at high doses. No adverse reactions, acute toxicity, or immunologic response were observed. The efficacy of the virus inactivation procedure was tested with model viruses. Reconstituted Protexel® was stable up to 24 hours at room temperature.
The recommended dosing regimen of Protexel® is similar to that of Ceprotin®: for neonatal purpura fulminans or acute thrombosis in severe protein C deficiency 60 IU/kg initial bolus, repeated 4 times daily, under monitoring of plasma protein C activity (aimed to minimal levels of 0.25 IU/mL), D-dimer, or prothrombin fragment 1 + 2.
A comprehensive report on the use of this concentrate in patients with inherited protein C deficiency was by Dreyfus et al (2007)
. The authors performed a retrospective workup of 9 patients (5 male, 4 female, age 3 days to 52 years), treated in 7 centers in France for protein C deficiency. Four patients had homozygous deficiency, 1 double heterozygous, 3 heterozygous, and 1 protein C deficiency of unknown origin. Indications for therapy were neonatal purpura fulminans (n = 1), necrotic hematomas (n = 19), venous thrombo-embolism (n = 2), and problems during vitamin K antagonist therapy (n = 5). Thirty courses of treatment were given, ranging from 1 day to 33 months. In total, 914 infusions/883,110 IU on 2006 cumulative exposure days to protein C concentrate from 26 different batches were performed. Recovery analysis demonstrated a post-infusion increase of protein C levels between 0.8 and 1.1% per kg body weight. Clinical response was sufficient in all cases, as justified by the investigators. The safety profile was excellent; no untoward side effects were observed, even not high doses (up to 209 IU/kg/day). No abnormal bleeding occurred, and no evidence of blood-born infection transmission.
Drotrecogin alpha activated (Xigris®)
Drotrecogin alpha (activated) (Xigris®, Eli Lilly Co.) is available as is a recombinant analogue to the physiologic human activated protein C. It is approved for the adjunctive therapy of adult patients with severe sepsis. The recommended dose of Xigris® in this indication is 24 μg/kg/hour, given as a continuous intravenous infusion for a total duration of 96 hours. Xigris is not approved for the treatment of congenital protein C deficiency, but single case reports suggest efficacy. However, the optimal dose and duration of applications are not defined.
One paper has reported report on the use of recombinant activated protein C to treat an episode of purpura fulminans in a teenage girl with severe protein C deficiency who had developed anaphylaxis to fresh-frozen plasma that was given in the past to treat recurrent episodes of purpura fulminans (Manco-Johnson et al 2004
). Infusion of activated protein C (20 μg/kg/hour for 10 hours) reduced d-dimer levels from 6450 to 847 ng/mL, indicating a control of coagulopathy, and reduced skin lesions. The teenager was then treated with heparin overlapping with warfarin for 4 days until the INR was more than 3.5 and the d-dimer level <230 ng/mL. At the end of the activated protein C infusion, all skin lesions of PF were resolved. There were no adverse reactions to activated protein C.
Another report was published by a Japanese group, who used another concentrate of activated protein C to treat a female newborn who developed purpura fulminans on the third day after birth due to homozygous protein C deficiency (Nakayama et al 2000
). Intravenous infusions of activated protein C markedly improved the necrotic skin lesions and enabled successful control of coagulopathy.
In conclusion, there is some evidence that activated protein C may also be effective in treating congenital protein C deficiency. It may be used in emergency cases when Ceprotin® is not available.