Telaprevir adverse reactions

# Adverse Reactions
The following adverse reactions are discussed in greater detail in other sections of the label:
- Serious Skin Reactions/Rash 
- Anemia 
- Pregnancy: Use with ribavirin and Peginterferon alfa 
INCIVEK must be administered with peginterferon alfa and ribavirin. Refer to their respective prescribing information for their associated adverse reactions.

## Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.
The safety assessment is based on data from pooled adequate and well-controlled clinical trials including 1797 subjects who received INCIVEK combination treatment and 493 who received peginterferon alfa and ribavirin.
Serious adverse drug reactions occurred in 3% of subjects who received INCIVEK combination treatment compared to none of the subjects treated with peginterferon alfa and ribavirin. The most frequent serious adverse events in subjects treated with INCIVEK combination treatment were skin disorders (rash and/or pruritus) and anemia . Fourteen percent of subjects discontinued INCIVEK due to adverse drug reactions. Rash, anemia, fatigue, pruritus, nausea, and vomiting were the most frequent adverse drug reactions leading to discontinuation of INCIVEK.
INCIVEK was administered in combination with peginterferon alfa and ribavirin. The following table lists adverse drug reactions that occurred in subjects treated with INCIVEK with an incidence at least 5% greater than in subjects receiving peginterferon alfa and ribavirin alone (Table 4).

## Description of Selected Adverse Drug Reactions

### Anorectal Signs and Symptoms
In the controlled clinical trials, 29% of subjects treated with INCIVEK combination treatment experienced anorectal adverse events, compared to 7% of those treated with peginterferon alfa and ribavirin alone. The majority of these events (e.g., hemorrhoids, anorectal discomfort, anal pruritus, and rectal burning) were mild to moderate in severity; less than 1% led to treatment discontinuation and all resolved during or after completion of INCIVEK dosing.

### Laboratory abnormalities
White Blood Cells: Treatment with peginterferon alfa is associated with decreases in mean values for total white blood cell, absolute neutrophil, and absolute lymphocyte count. More subjects treated with INCIVEK had decreases in lymphocyte counts to 499/mm3 or less (15% compared to 5%). Decreases in total white cell counts to 1,499/mm3 or less were comparable (8% compared to 5%). The incidence of decreases in absolute neutrophil counts to 749/mm3 or less was 15% in subjects treated with peginterferon alfa and ribavirin alone compared to 12% among those treated with INCIVEK combination treatment.
Platelets: Treatment with peginterferon alfa is associated with decreases in mean platelet counts. More patients treated with INCIVEK combination treatment had decreases in mean platelet values of all grades: 47% compared to 36% treated with peginterferon alfa and ribavirin alone. Three percent of INCIVEK combination treatment subjects had decreases to 49,999/mm3 or less compared to 1% of those treated with peginterferon alfa and ribavirin-treated alone.
Bilirubin: Forty one percent of subjects treated with INCIVEK compared to 28% of peginterferon alfa and ribavirin-treated subjects had all grade elevations in bilirubin levels; 4% and 2% of subjects, respectively, had greater than or equal to 2.6  ULN elevations. Bilirubin levels increased most steeply during the first 1 to 2 weeks of INCIVEK dosing, stabilized and between Weeks 12 and 16 were at baseline levels.
Uric Acid: During the INCIVEK combination treatment period, 73% of subjects had elevated uric acid levels compared to 29% for those treated with peginterferon alfa and ribavirin alone. Shifts to greater than or equal to 12.1 mg per dL from baseline in uric acid levels were also more frequent among subjects treated with INCIVEK (7%) compared to peginterferon alfa and ribavirin (1%). Less than 1% of subjects had clinical events of gout/gouty arthritis; none were serious and none resulted in treatment discontinuation.

### Additional Data from Clinical Trials
In the analysis of an additional study (Trial C211), the safety profile of combination treatment with INCIVEK 1125 mg twice daily was similar to the safety profile for patients receiving combination treatment with INCIVEK 750 mg every 8 hours (q8h) . No new safety findings were identified.

## Post-marketing Experience
The following adverse reactions have been identified during post-approval use of INCIVEK. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Skin and Subcutaneous Tissue Disorders: Toxic Epidermal Necrolysis (TEN) and Erythema Multiforme (EM) 
Renal and Urinary Disorders: Pre-renal azotemia with or without acute renal insufficiency/failure, uric acid nephropathy.