Krystexxa

Krystexxa

SIDE EFFECTS

The most commonly reported serious adverse reactions from pre-marketing controlled clinical trials were anaphylaxis, which occurred at a frequency of 6.5% in patients treated with KRYSTEXXA (pegloticase injection) 8 mg every 2 weeks, compared to none with placebo; infusion reactions, which occurred at a frequency of 26% in patients treated with KRYSTEXXA (pegloticase injection) 8 mg every 2 weeks, compared to 5% treated with placebo; and gout flares, which were more common during the first 3 months of treatment with KRYSTEXXA (pegloticase injection) compared with placebo. All patients in pre-marketing controlled clinical trials were pre-treated with an oral antihistamine, intravenous corticosteroid and/or acetaminophen to prevent anaphylaxis and infusion reaction. Patients also received non-steroidal anti-inflammatory drugs or colchicine, or both, for at least 7 days as gout flare prophylaxis before beginning KRYSTEXXA treatment, [see Boxed Warning, WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

The data described below reflect exposure to KRYSTEXXA (pegloticase injection) in patients with chronic gout refractory to conventional therapy in two replicate randomized, placebo-controlled, double-blind 6-month clinical trials: 85 patients were treated with KRYSTEXXA (pegloticase injection) 8 mg every 2 weeks; 84 patients were treated with KRYSTEXXA (pegloticase injection) 8 mg every 4 weeks; and 43 patients were treated with placebo. These patients were between the ages of 23 and 89 years (average 55 years); 173 patients were male and 39 were female; and 143 patients were White/Caucasian, 27 were Black/African American, 24 were Hispanic/Latino and 18 were all other ethnicities. Common co-morbid conditions among the enrolled patients included hypertension (72%), dyslipidemia (49%), chronic kidney disease (28%), diabetes (24%), coronary artery disease (18%) arrhythmia(16%) and cardiac failure/left ventrieute dysfunction (12%).

Because clinical studies are conducted under widely varying and controlled conditions, adverse reaction rates observed in clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug, and may not predict the rates observed in a broader patient population in clinical practice.

Anaphylaxis

Diagnostic criteria of anaphylaxis were skin or mucosal tissue involvement, and, either airway compromise, and/or reduced blood pressure with or without associated symptoms, and a temporal relationship to KRYSTEXXA (pegloticase injection) or placebo injection with no other identifiable cause. Using these clinical criteria, anaphylaxis was identified in 14 (5.1%) of 273 total patients studied in the clinical program of IV KRYSTEXXA (pegloticase injection) . The frequency was 6.5% for the every 2-week dosing regimen (8 of 123 patients), and 4.8% for the 4-week dosing frequency (6 of 126) of KRYSTEXXA (pegloticase injection) . There were no cases of anaphylaxis in patients receiving placebo. Anaphylaxis generally occurred within 2 hours after treatment. This occurred with patients being pre-treated with an oral antihistamine, intravenous corticosteroid, and acetaminophen, [see Boxed Warning, WARNINGS AND PRECAUTIONS]

Infusion Reactions

Infusion reactions occurred in 26% of patients in the 2 week dosing regimen group and 41% of patients in the 4 week dosing regimen group^ compared to 5% of placebo-treated patients. Manifestations of these reactions included urticaria (frequency of 10.6%), dyspnea (frequency of 7.1%), chest discomfort (frequency of 9.5%), chest pain (frequency of 9.5%), erythema (frequency of 9.5%), and pruritus (frequency of 9.5%). These manifestations overlap with the symptoms of anaphylaxis, but in a given patient did not occur together to satisfy the clinical criteria for diagnosing anaphylaxis. Infusion reactions are thought to result from release of various mediators, such as cytokines. Infusion reactions occurred at any time during a course of treatment with approximately 3% occurring with the first infusion^ and approximately 91% occurred during the time of infusion. Some infusion reaction manifestations were reduced with slowing the rate of infusion, or stopping the infusion and restarting the infusion at a slower rate. These infusion reactions occurred with all patients being pre-treated with an oral antihistamine, intravenous corticosteroid and acetaminophen. [see Boxed Warning, WARNINGS AND PRECAUTIONS]

Gout Flares

Gout flares were common in the study patients before randomization to treatment, with patients experiencing an average of 10 flares in the preceding 18 months prior to study entry. During the controlled treatment period with KRYSTEXXA (pegloticase injection) or placebo, the frequencies of gout flares were high in all treatment groups, but more so with KRYSTEXXA (pegloticase injection) treatment during the first 3 months of treatment, which seemed to decrease in the subsequent 3 months of treatment. The percentages of patients with any flare for the first 3 months were 74%, 81 %, and 51 %, for KRYSTEXXA (pegloticase injection) 8 mg every 2 weeks, KRYSTEXXA (pegloticase injection) 8 mg every 4 weeks, and placebo, respectively. The percentages of patients with any flare for the subsequent 3 months were 41%, 57% and 67%, for KRYSTEXXA (pegloticase injection) 8 mg every 2 weeks, KRYSTEXXA (pegloticase injection) 8 mg every 4 weeks, and placebo, respectively. Patients received gout flare prophylaxis with colchicine and/or nonsteroidal anti-inflammatory drugs (NS AIDs) starting at least one week before receiving KRYSTEXXA. [see WARNINGS AND PRECAUTIONS]

Congestive Heart Failure

Two cases of congestive heart failure exacerbation occurred during the trials in patients receiving treatment with KRYSTEXXA (pegloticase injection) 8 mg every 2 weeks. No cases were reported in placebo-treated patients. Four subjects had exacerbations of pre-existing congestive heart failure while receiving KRYSTEXXA (pegloticase injection) 8 mg every 2 weeks during the open-label extension study, [see WARNINGS AND PRECAUTIONS].

Other Adverse Reactions

The most commonly reported adverse reactions that occurred in greater than or equal to 5% of patients treated with KRYSTEXXA (pegloticase injection) 8mg every 2 weeks are provided in Table I.

Table 1. Adverse Reactions Occurring in 5% or More of Patients Treated with KRYSTEXXA (pegloticase injection) Compared to Placebo

Adverse Reaction
(Preferred Term)
KRYSTEXXA (pegloticase injection)
8 mg every 2 weeks
(N-85)
Na (%)
Placebo
(N=43)
N (%)
Gout flare 65(77%) . 35 (81%)
Infusion reaction 22 (26%) 2(5%)
Nausea 10(12%) 1 (2%)
Contusionb or Ecchymosisb 9(11%) 2 (5%)
Nasopharyngitis 6(7%). 1(2%)
Constipation 5 (6%) 2 (5%)
Chest Pain 5(6%) 1 (2%)
Anaphylaxis 4 (5%) 0 (0%)
Vomiting 4 (5%) 1 (2%)
a If the same subject in a given group had more than one occurrence in the same preferred term event category, the subject was counted only once.
b Most did not occur on the day of infusion and could be related to other factors (e.g. concomitant medications relevant to contusion or ecchymosis, insulin dependent diabetes mellitus).

Immunogenicity

Anti-pegloticase antibodies developed in 92% of patients treated with KRYSTEXXA (pegloticase injection) every 2 weeks, and 28% for placebo. Anti-PEG antibodies were also detected in 42% of patients treated with KRYSTEXXA. High anti-pegloticase antibody titer was associated with a failure to maintain pegloticase-induced normalization of uric acid. The impact of anti-PEG antibodies on patients' responses to other PEG-containing therapeutics is unknown.

There was a higher incidence of infusion reactions in patients with high anti-pegloticase antibody titer: 53% (16 of 30) in the KRYSTEXXA (pegloticase injection) every 2 weeks group compared to 6% in patients who had undetectable or low antibody titers.

As with all therapeutic proteins, there is a potential for immunogenicity. The observed incidence of antibody positivity in an assay is highly dependent on several factors including assay sensitivity and specificity and assay methodology, sample handling, timing of sample collection, concomitant medications, and underlying disease. For these reasons, the comparison of the incidence of antibodies to pegloticase with the incidence of antibodies to other products may be misleading.

Read the Krystexxa (pegloticase injection) Side Effects Center for a complete guide to possible side effects

DRUG INTERACTIONS

No studies of interactions of KRYSTEXXA with other drugs have been conducted. Because anti-pegloticase antibodies appear to bind to the PEG portion of the drug, there may be potential for binding with other PEGylated products. The impact of anti-PEG antibodies on patients' responses to other PEG-containing therapeutics is unknown.

Read the Krystexxa Drug Interactions Center for a complete guide to possible interactions

Last reviewed on RxList: 7/12/2012
This monograph has been modified to include the generic and brand name in many instances.

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