Xifaxan Side Effects, and Drug Interactions - Rifaximin

Xifaxan Side Effects, and Drug Interactions - Rifaximin

SIDE EFFECTS

The safety of XIFAXAN™ Tablets 200 mg taken three times a day (TID) was evaluated in 320patients in two placebo-controlled clinical trials with 95% of patients receiving at least three days of treatment with XIFAXAN™ Tablets. All adverse events for XIFAXAN™ Tablets 200 mg TID that occurred at a frequency ³2% in the two placebo-controlled trials combined are provided in Table 2. (These include adverse events that may be attributable to the underlying disease.)

The following adverse events, presented by body system, have also been reported in <2% of patients taking XIFAXAN™ Tablets in the two placebo-controlled clinical trials where the 200 mg taken three times a day dose was used. The following includes adverse events regardless of causal relationship to drug exposure.

Blood and Lymphatic System Disorders: lymphocytosis, monocytosis, neutropenia

Ear and Labyrinth Disorders: ear pain, motion sickness, tinnitus

Gastrointestinal Disorders: abdominal distension, diarrhea NOS, dry throat, fecal abnormality NOS, gingival disorder NOS, inguinal hernia NOS, dry lips, stomach discomfort

General Disorders and Administration Site Conditions: chest pain, fatigue, malaise, pain NOS, weakness

Infections and Infestations: dysentery NOS, respiratory tract infection NOS, upper respiratory tract infection NOS

Injury and Poisoning: sunburn

Investigations: aspartate aminotransferase increased, blood in stool, blood in urine, weight decreased

Metabolic and Nutritional Disorders: anorexia, dehydration

Musculoskeletal, Connective Tissue, and Bone Disorders: arthralgia, muscle spasms, myalgia, neck pain

Nervous System Disorders: abnormal dreams, dizziness, migraine NOS, syncope, loss of taste

Psychiatric Disorders: insomnia

Renal and Urinary Disorders: choluria, dysuria, hematuria, polyuria, proteinuria, urinary frequency

Respiratory, Thoracic, and Mediastinal Disorders: dyspnea NOS, nasal passage irritation, nasopharyngitis, pharyngitis, pharyngolaryngeal pain, rhinitis NOS, rhinorrhea

Skin and Subcutaneous Tissue Disorders: clamminess, rash NOS, sweating increased

Vascular Disorders: hot flashes NOS

The following events: hypersensitivity reactions, including allergic dermatitis, rash, angioneurotic edema, urticaria, and pruritus; have been identified during foreign post-approval use of XIFAXAN™ Tablets. Because these events are reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency or establish a causal relationship to drug exposure.

None reported.

None reported.

DRUG INTERACTIONS

Although in vitro studies demonstrated the potential of rifaximin to interact with cytochrome P450 3A4 (CYP3A4), a clinical drug-drug interaction study demonstrated that rifaximin did not significantly affect the pharmacokinetics of midazolam either presystemically or systemically. An additional clinical drug-drug interaction study showed no effect of rifaximin on the presystemic metabolism of an oral contraceptive containing ethinyl estradiol and norgestimate. Therefore, clinical interactions with drugs metabolized by human cytochrome P450 isoenzymes are not expected (see Pharmacokinetics and Drug-Drug Interactions under CLINICAL PHARMACOLOGY).