Concomitant Use of Hormonal Contraceptives

Combination hormonal contraceptives are known to increase the risk of venous thromboembolism, as well as arterial thromboses such as stroke and myocardial infarction. Because tranexamic acid tablets are antifibrinolytic, the risk of venous thromboembolism, as well as arterial thromboses such as stroke, may increase further when hormonal contraceptives are administered with tranexamic acid tablets. This is of particular concern in women who are obese or smoke cigarettes, especially smokers over 35 years of age [see Contraindications (4.1) and Drug Interactions (7.1)].

Women using hormonal contraception were excluded from the clinical trials supporting the safety and efficacy of tranexamic acid tablets, and there are no clinical trial data on the risk of thrombotic events with the concomitant use of tranexamic acid tablets with hormonal contraceptives. There have been US postmarketing reports of venous and arterial thrombotic events in women who have used tranexamic acid tablets concomitantly with combined hormonal contraceptives. Women using hormonal contraception, especially those who are obese or smoke, should use tranexamic acid tablets only if there is a strong medical need and the benefit of treatment will outweigh the potential increased risk of a thrombotic event. Do not use tranexamic acid tablets in women who are taking more than the approved dose of a hormonal contraceptive.

Factor IX Complex Concentrates or Anti-Inhibitor Coagulant Concentrates

Tranexamic acid tablets are not recommended for women taking either Factor IX complex concentrates or anti-inhibitor coagulant concentrates because the risk of thrombosis may be increased [see Drug Interactions (7.3) and Clinical Pharmacology (12.3)].

All-Trans Retinoic Acid (Oral Tretinoin)

Exercise caution when prescribing tranexamic acid tablets to women with acute promyelocytic leukemia taking all-trans retinoic acid for remission induction because of possible exacerbation of the procoagulant effect of all-trans retinoic acid [see Drug Interactions (7.4) and Clinical Pharmacology (12.3)].

Ocular Effects

Retinal venous and arterial occlusion has been reported in patients using tranexamic acid. Patients should be instructed to report visual and ocular symptoms promptly. In the event of such symptoms, patients should be instructed to discontinue tranexamic acid tablets immediately and should be referred to an ophthalmologist for a complete ophthalmic evaluation, including dilated retinal examination, to exclude the possibility of retinal venous or arterial occlusion.

Short-term Studies

The safety of tranexamic acid tablets in the treatment of heavy menstrual bleeding (HMB) was studied in two randomized, double-blind, placebo-controlled studies [see Clinical Studies (14)]. One study compared the effects of two doses of tranexamic acid tablets (1950 mg and 3900 mg given daily for up to 5 days during each menstrual period) versus placebo over a 3-cycle treatment duration. A total of 304 women were randomized to this study, with 115 receiving at least one dose of 3900 mg/day of tranexamic acid tablets. A second study compared the effects of tranexamic acid tablets (3900 mg/day) versus placebo over a 6-cycle treatment duration. A total of 196 women were randomized to this study, with 117 receiving at least one dose of tranexamic acid tablets. In both studies, subjects were generally healthy women who had menstrual blood loss of ≥ 80 mL.

In these studies, subjects were 18 to 49 years of age with a mean age of approximately 40 years, had cyclic menses every 21-35 days, and a BMI of approximately 32 kg/m2. On average, subjects had a history of HMB for approximately 10 years and 40% had fibroids as determined by transvaginal ultrasound. Approximately 70% were Caucasian, 25% were Black, and 5% were Asian, Native American, Pacific Islander, or Other. Seven percent (7%) of all subjects were of Hispanic origin. Women using hormonal contraception were excluded from the trials.

The rates of discontinuation due to adverse events during the two clinical trials were comparable between tranexamic acid tablets and placebo. In the 3-cycle study, the rate in the 3900 mg tranexamic acid tablets dose group was 0.8% as compared to 1.4% in the placebo group. In the 6-cycle study, the rate in the tranexamic acid tablets group was 2.4% as compared to 4.1% in the placebo group. Across the studies, the combined exposure to 3900 mg/day tranexamic acid tablets was 947 cycles and the average duration of use was 3.4 days per cycle.

A list of adverse events occurring in ≥ 5% of subjects and more frequently in tranexamic acid tablets treated subjects receiving 3900 mg/day compared to placebo is provided in Table 2.

Long-term Studies

Long-term safety of tranexamic acid tablets was studied in two open-label studies. In one study, subjects with physician-diagnosed heavy menstrual bleeding (not using the alkaline hematin methodology) were treated with 3900 mg/day for up to 5 days during each menstrual period for up to 27 menstrual cycles. A total of 781 subjects were enrolled and 239 completed the study through 27 menstrual cycles. A total of 12.4% of the subjects withdrew due to adverse events. Women using hormonal contraception were excluded from the study. The total exposure in this study to 3900 mg/day tranexamic acid tablets was 10,213 cycles. The average duration of tranexamic acid tablets use was 2.9 days per cycle.

A long-term open-label extension study of subjects from the two short-term efficacy studies was also conducted in which subjects were treated with 3900 mg/day for up to 5 days during each menstrual period for up to 9 menstrual cycles. A total of 288 subjects were enrolled and 196 subjects completed the study through 9 menstrual cycles. A total of 2.1% of the subjects withdrew due to adverse events. The total exposure to 3900 mg/day tranexamic acid tablets in this study was 1,956 cycles. The average duration of tranexamic acid tablets use was 3.5 days per cycle.

The types and severity of adverse events in these two long-term open-label trials were similar to those observed in the double-blind, placebo-controlled studies although the percentage of subjects reporting them was greater in the 27-month study, most likely because of the longer study duration.

A case of severe allergic reaction to tranexamic acid tablets was reported in the extension trial, involving a subject on her fourth cycle of treatment, who experienced dyspnea, tightening of her throat, and facial flushing that required emergency medical treatment.

Cardiac Electrophysiology

The effect of tranexamic acid tablets on QT interval was evaluated in a randomized, single-dose, 4-way crossover study in 48 healthy females aged 18 to 49 years. Subjects received (1) tranexamic acid tablets 1300 mg (two 650 mg tablets), (2) tranexamic acid tablets 3900 mg (six 650 mg tablets; three times the recommended single dose), (3) moxifloxacin 400 mg, and (4) placebo. There was no significant increase in the corrected QT interval at any time up to 24 hours after the administration of either dose of tranexamic acid tablets. Moxifloxacin, the active control, was associated with a maximum 14.11 msec mean increase in corrected QT interval (moxifloxacin – placebo) at 3 hours after administration.

Absorption

After a single oral administration of two 650 mg tablets of tranexamic acid, the peak plasma concentration (Cmax) occurred at approximately 3 hours (Tmax). The absolute bioavailability of tranexamic acid tablets in women aged 18-49 is approximately 45%. Following multiple oral doses (two 650 mg tablets three times daily) administration of tranexamic acid tablets for 5 days, the mean Cmax increased by approximately 19% and the mean area under the plasma concentration-time curve (AUC) remained unchanged, compared to a single oral dose administration (two 650 mg tablets). Plasma concentrations reached steady state at the 5th dose of tranexamic acid tablets on Day 2.

The mean plasma pharmacokinetic parameters of tranexamic acid determined in 19 healthy women following a single (two 650 mg tablets) and multiple (two 650 mg tablets three times daily for 5 days) oral dose of tranexamic acid tablets are shown in Table 3.

Effect of food: Tranexamic acid tablets may be administered without regard to meals. A single dose administration (two 650 mg tablets) of tranexamic acid tablets with food increased both Cmax and AUC by 7% and 16%, respectively.

Distribution

Tranexamic acid is 3% bound to plasma proteins with no apparent binding to albumin. Tranexamic acid is distributed with an initial volume of distribution of 0.18 L/kg and steady-state apparent volume of distribution of 0.39 L/kg.

Tranexamic acid crosses the placenta. The concentration in cord blood after an intravenous injection of 10 mg/kg to pregnant women is about 30 mg/L, as high as in the maternal blood.

Tranexamic acid concentration in cerebrospinal fluid is about one tenth of the plasma concentration.

The drug passes into the aqueous humor of the eye achieving a concentration of approximately one tenth of plasma concentrations.

Metabolism

A small fraction of the tranexamic acid is metabolized.

Excretion

Tranexamic acid is eliminated by urinary excretion primarily via glomerular filtration with more than 95% of the dose excreted unchanged. Excretion of tranexamic acid is about 90% at 24 hours after intravenous administration of 10 mg/kg. Most elimination post intravenous administration occurred during the first 10 hours, giving an apparent elimination half-life of approximately 2 hours. The mean terminal half-life of tranexamic acid tablets is approximately 11 hours. Plasma clearance of tranexamic acid is 110-116 mL/min.

Specific Populations

Drug Interactions

No drug-drug interaction studies were conducted with tranexamic acid tablets.

Carcinogenesis

Carcinogenicity studies with tranexamic acid in male mice at doses as high as 6 times the recommended human dose of 3900 mg/day showed an increased incidence of leukemia which may have been related to treatment. Female mice were not included in this experiment.

The dose multiple referenced above is based on body surface area (mg/m2). Actual daily dose in mice was up to 5000 mg/kg/day in food.

Hyperplasia of the biliary tract and cholangioma and adenocarcinoma of the intrahepatic biliary system have been reported in one strain of rats after dietary administration of doses exceeding the maximum tolerated dose for 22 months. Hyperplastic, but not neoplastic, lesions were reported at lower doses. Subsequent long-term dietary administration studies in a different strain of rat, each with an exposure level equal to the maximum level employed in the earlier experiment, have failed to show such hyperplastic/neoplastic changes in the liver.

Mutagenesis

Tranexamic acid was neither mutagenic nor clastogenic in the in vitro Bacterial Reverse Mutation Assay (Ames test), in vitro chromosome aberration test in Chinese hamster cells, and in in vivo chromosome aberration tests in mice and rats.

Impairment of Fertility

Reproductive studies performed in mice, rats and rabbits have not revealed any evidence of impaired fertility or adverse effects on the fetus due to tranexamic acid.

In a rat embryo-fetal developmental toxicity study, tranexamic acid had no adverse effects on embryo-fetal development when administered during the period of organogenesis (from gestation days 6 through 17) at doses 1, 2 and 4 times the recommended human oral dose of 3900 mg/day. In a perinatal-postnatal study in rats, tranexamic acid had no adverse effects on pup viability, growth or development when administered from gestation day 6 through postnatal day 20 at doses 1, 2 and 4 times the recommended human oral dose of 3900 mg/day.

The dose multiples referenced above are based on body surface area (mg/m2). Actual daily doses in rats were 300, 750 or 1500 mg/kg/day.

Ocular Effects

In a 9-month toxicology study, dogs were administered tranexamic acid in food at doses of 0, 200, 600, or 1200 mg/kg/day. These doses are approximately 2, 5, and 6 times, respectively, the recommended human oral dose of 3900 mg/day based on AUC. At 6 times the human dose, some dogs developed reversible reddening and gelatinous discharge from the eyes. Ophthalmologic examination revealed reversible changes in the nictitating membrane/conjunctiva. In some female dogs, the presence of inflammatory exudate over the bulbar conjunctival mucosa was observed. Histopathological examinations did not reveal any retinal alteration. No adverse effects were observed at 5 times the human dose.

In other studies, focal areas of retinal degeneration were observed in cats, dogs and rats following oral or intravenous tranexamic acid doses at 6-40 times the recommended usual human dose based on mg/m2 (actual animal doses between 250-1600 mg/kg/day).