CLINICAL PHARMACOLOGY
Mechanism of Action
Tranexamic acid is a synthetic
lysine amino acid derivative, which diminishes the dissolution of hemostatic
fibrin by plasmin. In the presence of tranexamic acid, the lysine receptor
binding sites of plasmin for fibrin are occupied, preventing binding to fibrin
monomers, thus preserving and stabilizing fibrin's matrix structure.
The antifibrinolytic effects of
tranexamic acid are mediated by reversible interactions at multiple binding
sites within plasminogen. Native human plasminogen contains 4 to 5 lysine binding
sites with low affinity for tranexamic acid (K d = 750 μmol/L) and 1 with
high affinity (Kd = 1.1 μmol/L). The high affinity lysine site of
plasminogen is involved in its binding to fibrin. Saturation of the high
affinity binding site with tranexamic acid displaces plasminogen from the
surface of fibrin. Although plasmin may be formed by conformational changes in
plasminogen, binding to and dissolution of the fibrin matrix is inhibited.
Pharmacodynamics
Tranexamic acid, at in vitro concentrations
of 25 - 100 M, reduces by 20 - 60% the maximal rate of plasmin lysis of fibrin
catalyzed by tissue plasminogen activator (tPA).
Elevated concentrations of
endometrial, uterine, and menstrual blood tPA are observed in women with heavy
menstrual bleeding (HMB) compared to women with normal menstrual blood loss.
The effect of tranexamic acid on lowering endometrial tPA activity and
menstrual fluid fibrinolysis is observed in women with HMB receiving tranexamic
acid total oral doses of 2-3 g/day for 5 days.
In healthy subjects, tranexamic
acid at blood concentrations less than 10 mg/mL has no effect on the platelet
count, the coagulation time or various coagulation factors in whole blood or
citrated blood. Tranexamic acid, however, at blood concentrations of 1 and 10
mg/mL prolongs the thrombin time.
Cardiac Electrophysiology
The effect of LYSTEDA 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) LYSTEDA 1300 mg (two
650 mg tablets), (2) LYSTEDA 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 LYSTEDA. 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.
Pharmacokinetics
Absorption
After a single oral
administration of two 650 mg tablets of LYSTEDA, the peak plasma concentration
(Cmax ) occurred at approximately 3 hours (Tmax ). The absolute bioavailability
of LYSTEDA in women aged 18-49 is approximately 45%. Following multiple oral
doses (two 650 mg tablets three times daily) administration of LYSTEDA
for 5 days, the mean C max 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 LYSTEDA 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 LYSTEDA
are shown in Table 3.
Table 3: Mean (CV%) Pharmacokinetic Parameters
Following a Single (two 650 mg tablets) and Multiple Oral Dose (two 650 mg
tablets three time daily for 5 days) Administration of LYSTEDA in 19 Healthy
Women under Fasting Conditions
Parameter |
Arithmetic Mean (CV%) |
Single dose |
Multiple dose |
Cmax (mcg/mL) |
13.83 (32.14) |
16.41 (26.19) |
AUCtldc (mcg•h/mL) |
77.96 (31.14) |
77.67a (29.39) |
AUCinf (mcg•h/mL) |
80.19 (30.43) |
- |
Tmax (h)b |
2.5 (1 – 5) |
2.5 (2 – 3.5) |
t½ (h) |
11.08 (16.94) |
- |
Cmax = maximum concentration
AUCtldc = area under the drug concentration curve from time 0 to time of last
determinable concentration
AUCinf = area under the drug concentration curve from time 0 to infinity
Tmax = time to maximum concentration
t½ = terminal elimination half-life
aAUC0-tau (mcg·h/mL) = area under the drug concentration curve from
time 0 to 8 hours
bData presented as median (range) |
Effect of food: LYSTEDA may be
administered without regard to meals. A single dose administration (two 650 mg
tablets) of LYSTEDA 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 LYSTEDA is approximately 11 hours. Plasma clearance of tranexamic
acid is 110-116 mL/min.
Specific Populations
Pregnancy (Category B)
LYSTEDA is not indicated for use in pregnant women. Tranexamic
acid is known to cross the placenta and appears in cord blood at concentrations
approximately equal to maternal concentration. There are no adequate and
well-controlled studies in pregnant women [see Use In Specific Populations].
Nursing Mothers
Tranexamic acid is present in the mother's milk at a
concentration of about one hundredth of the corresponding serum concentrations.
LYSTEDA should be used during lactation only if clearly needed [see Use in
Specific Populations].
Pediatric Use
LYSTEDA is indicated for women of reproductive age and is
not intended for use in premenarcheal girls. In a randomized, single dose,
two-way crossover study of two dose levels (650 mg and 1,300 mg [two 650 mg
tablets]), pharmacokinetics of tranexamic acid was evaluated in 20 female
adolescents (12 to 16 years of age) with heavy menstrual bleeding. The Cmax and
AUC values after a single oral dose of 650 mg in the adolescent females were 32
– 36% less than those after a single oral dose of 1,300 mg in the adolescent
females. The Cmax and AUC values after a single oral dose of 1300 mg in the
adolescent females were 20 – 25% less than those in the adult females given the
same dose in a separate study. [See Use In Specific Populations]
Geriatric Use
LYSTEDA is indicated for women of reproductive age and is
not intended for use by postmenopausal women.
Renal Impairment
The effect of renal impairment on the disposition of
LYSTEDA has not been evaluated. Urinary excretion following a single
intravenous injection of tranexamic acid declines as renal function decreases.
Following a single 10 mg/kg intravenous injection of tranexamic acid in 28
patients, the 24-hour urinary fractions of tranexamic acid with serum
creatinine concentrations 1.4 – 2.8, 2.8 – 5.7, and greater than 5.7 mg/dL were
51, 39, and 19%, respectively. The 24-hour tranexamic acid plasma
concentrations for these patients demonstrated a direct relationship to the
degree of renal impairment. Therefore, dose adjustment is needed in patients
with renal impairment [see DOSAGE AND ADMINISTRATION].
Hepatic Impairment
The effect of hepatic impairment on the disposition of
LYSTEDA has not been evaluated. One percent and 0.5 percent of an oral dose are
excreted as a dicarboxylic acid and acetylated metabolite, respectively.
Because only a small fraction of the drug is metabolized, no dose adjustment is
needed in patients with hepatic impairment.
Drug Interactions
No drug-drug interaction studies were conducted with
LYSTEDA.
Hormonal Contraceptives
Because LYSTEDA is antifibrinolytic, concomitant use of
hormonal contraception and LYSTEDA may further exacerbate the increased
thrombotic risk associated with combination hormonal contraceptives. For this
reason, concomitant use of LYSTEDA with combination hormonal contraceptives is
contraindicated [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS and
DRUG INTERACTIONS].
Factor IX Complex Concentrates or Anti-inhibitor
Coagulant Concentrates
LYSTEDA is not recommended in patients taking either
Factor IX complex concentrates or anti-inhibitor coagulant concentrates because
the risk of thrombosis may be increased [see WARNINGS AND PRECAUTIONS and
DRUG INTERACTIONS].
Tissue Plasminogen Activators
Concomitant therapy with tissue plasminogen activators
may decrease the efficacy of both LYSTEDA and tissue plasminogen activators.
Therefore, exercise caution if a patient taking LYSTEDA therapy requires tissue
plasminogen activators [see DRUG INTERACTIONS].
All-Trans Retinoic Acid (Oral Tretinoin)
In a study involving 28 patients with acute promyelocytic
leukemia who were given either orally administered all-trans retinoic acid plus
intravenously administered tranexamic acid, all-trans retinoic acid plus
chemotherapy, or all-trans retinoic acid plus tranexamic acid plus
chemotherapy, all 4 patients who were given all-trans retinoic acid plus
tranexamic acid died, with 3 of the 4 deaths due to thrombotic complications.
It appears that the procoagulant effect of all-trans retinoic acid may be
exacerbated by concomitant use of tranexamic acid. Therefore, exercise caution
when prescribing LYSTEDA to patients with acute promyelocytic leukemia taking
all-trans retinoic acid [see WARNINGS AND PRECAUTIONS and DRUG
INTERACTIONS].
Animal Toxicology and/or Pharmacology
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).
Clinical Studies
The efficacy and safety of LYSTEDA in the treatment of
heavy menstrual bleeding (HMB) was demonstrated in one 3-cycle treatment and
one 6-cycle treatment, randomized, double-blind, placebo-controlled study [see ADVERSE
REACTIONS]. In these studies, HMB was defined as an average menstrual blood
loss of ≥ 80 mL as assessed by alkaline hematin analysis of collected
sanitary products over two baseline menstrual cycles. 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 an HMB history of 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.
In these studies, the primary outcome measure was
menstrual blood loss (MBL), measured using the alkaline hematin method. The
endpoint was change from baseline in MBL, calculated by subtracting the mean
MBL during treatment from the mean pretreatment MBL.
The key secondary outcome measures were based on specific
questions concerning limitations in social or leisure activities (LSLA) and
limitations in physical activities (LPA). Large stains (soiling beyond the
undergarment) were also included as a key secondary outcome measure.
Three-Cycle Treatment Study
This study compared the effects of two doses of LYSTEDA
(1950 mg and 3900 mg given daily for up to 5 days during each menstrual period)
versus placebo on MBL over a 3-cycle treatment duration. Of the 294 evaluable
subjects, 115 LYSTEDA 1950 mg/day subjects, 112 LYSTEDA 3900 mg/day subjects
and 67 placebo subjects took at least one dose of study drug and had
post-treatment data available.
Results are shown in Table 4. MBL was statistically
significantly reduced in patients treated with 3900 mg/day LYSTEDA compared to
placebo. Study success also required achieving a reduction in MBL that was
determined to be clinically meaningful to the subjects. The 1950 mg/day LYSTEDA
dose did not meet the criteria for success.
Table 4: Mean Reduction from Baseline in MBL
Treatment Arm |
N |
Baseline Mean MBL (mL) |
Least Squares Mean Reduction in MBL (mL) |
Percent Reduction in MBL |
LYSTEDA 3900 mg/day |
112 |
169 |
65* |
39% |
LYSTEDA 1950 mg/day |
115 |
178 |
44 |
25% |
Placebo |
67 |
154 |
7 |
5% |
*p < 0.001 versus placebo |
LYSTEDA also statistically
significantly reduced limitations on social, leisure, and physical activities
in the 3900 mg/day dose group compared to placebo (see Table 5). No
statistically significant treatment difference was observed in response rates
on the number of large stains.
Table 5: Secondary Outcomes
in 3-Cycle Study
Outcome Measure |
N |
Baseline Mean a |
Least Squares Mean Reduction b |
Social and Leisure Activities |
3900 mg/day LYSTEDA |
112 |
3.00 |
0.98c |
Placebo |
66 |
2.85 |
0.39 |
Physical Activities |
3900 mg/day LYSTEDA |
112 |
3.07 |
0.94c |
Placebo |
66 |
2.96 |
0.34 |
|
N |
|
Responders d |
Reduction in Large Stains |
3900 mg/day LYSTEDA |
111 |
|
64%e |
Placebo |
67 |
|
52% |
aResponse categories: 1=not at all limited;
2=slightly limited; 3=moderately limited; 4=quite a bit limited; 5=extremely limited
bPositive means reflect an improvement from baseline.
cp-value < 0.05 versus placebo
cResponders are defined as subjects who experienced a reduction from
baseline in frequency of large stains.
eNon-significant difference versus placebo |
Six-Cycle Treatment Study
This study compared the effects of
LYSTEDA 3900 mg/day given daily for up to 5 days during each menstrual period
versus placebo on MBL over a 6-cycle treatment duration. Of the 187 evaluable
subjects, 115 LYSTEDA subjects and 72 placebo subjects took at least one dose
of study drug and had post-treatment data available.
Results are shown in Table 6.
MBL was statistically significantly reduced in patients treated with 3900
mg/day LYSTEDA compared to placebo. Study success also required achieving a
reduction in MBL that was determined to be clinically meaningful to the
subjects.
Table 6: Mean Reduction from Baseline in MBL
Treatment Arm |
N |
Baseline Mean MBL (mL) |
Least Squares Mean Reduction in MBL (mL) |
Percent Reduction in MBL |
LYSTEDA 3900 mg/day |
115 |
172 |
66* |
38% |
Placebo |
72 |
153 |
18 |
12% |
* p < 0.001 versus placebo |
Limitations on social, leisure,
and physical activities were also statistically significantly reduced in the
LYSTEDA group compared to placebo (see Table 7). No statistically significant
treatment difference was observed in response rates on the number of large
stains.
Table 7: Secondary Outcomes
in 6-Cycle Study
Outcome Measure |
N |
Baseline Mean a |
Least Squares Mean Reduction b |
Social and Leisure Activities |
3900 mg/day LYSTEDA |
115 |
2.92 |
0.85c |
Placebo |
72 |
2.74 |
0.44 |
Physical Activities |
3900 mg/day LYSTEDA |
115 |
3.05 |
0.87c |
Placebo |
72 |
2.90 |
0.40 |
|
N |
|
Responders d |
Reduction in Large Stains |
3900 mg/day LYSTEDA |
115 |
|
57%e |
Placebo |
72 |
|
51% |
aResponse categories: 1=not at all limited;
2=slightly limited; 3=moderately limited; 4=quite a bit limited; 5=extremely limited
bPositive means reflect an improvement from baseline
cp-value < 0.05 versus placebo
dResponders are defined as subjects who experienced a reduction from
baseline in frequency of large stains
eNon-significant difference versus placebo |
MBL Results over Time
The efficacy of LYSTEDA 3900
mg/day over 3 menstrual cycles and over 6 menstrual cycles was demonstrated
versus placebo in the double-blind, placebo-controlled efficacy studies (see
Figure 1). The change in MBL from baseline was similar across all post-baseline
treatment cycles.
Figure 1: MBL Levels over Duration of Therapy