CLINICAL PHARMACOLOGY
Mechanism Of Action
Tadalafil is an inhibitor of phosphodiesterase type 5 (PDE5), the enzyme responsible for the
degradation of cyclic guanosine monophosphate (cGMP). Pulmonary arterial hypertension is associated
with impaired release of nitric oxide by the vascular endothelium and consequent reduction of cGMP
concentrations in the pulmonary vascular smooth muscle. PDE5 is the predominant phosphodiesterase in
the pulmonary vasculature. Inhibition of PDE5 by tadalafil increases the concentrations of cGMP
resulting in relaxation of pulmonary vascular smooth muscle cells and vasodilation of the pulmonary
vascular bed.
Studies in vitro have demonstrated that tadalafil is a selective inhibitor of PDE5. PDE5 is found in
pulmonary vascular smooth muscle, visceral smooth muscle, corpus cavernosum, skeletal muscle,
platelets, kidney, lung, cerebellum, and pancreas.
In vitro studies have shown that the effect of tadalafil is more potent on PDE5 than on other
phosphodiesterases. These studies have shown that tadalafil is > 10,000–fold more potent for PDE5
than for PDE1, PDE2, PDE4, and PDE7 enzymes, which are found in the heart, brain, blood vessels,
liver, leukocytes, skeletal muscle, and other organs. Tadalafil is > 10,000–fold more potent for PDE5
than for PDE3, an enzyme found in the heart and blood vessels. Additionally, tadalafil is 700–fold more
potent for PDE5 than for PDE6, which is found in the retina and is responsible for phototransduction.
Tadalafil is > 9,000-fold more potent for PDE5 than for PDE8, PDE9, and PDE10. Tadalafil is 14–fold
more potent for PDE5 than for PDE11A1 and 40–fold more potent for PDE5 than for PDE11A4, two of
the four known forms of PDE11. PDE11 is an enzyme found in human prostate, testes, skeletal muscle
and in other tissues. In vitro, tadalafil inhibits human recombinant PDE11A1 and, to a lesser degree,
PDE11A4 activities at concentrations within the therapeutic range. The physiological role and clinical
consequence of PDE11 inhibition in humans have not been defined.
Pharmacodynamics
Effects On Blood Pressure When Administered With Nitrates
In clinical pharmacology studies, tadalafil (5 to 20 mg) was shown to potentiate the hypotensive effect
of nitrates. Do not use ALYQ™ in patients taking any form of nitrates [see CONTRAINDICATIONS].
A double–blind, placebo–controlled, crossover study in 150 male subjects at least 40 years of age
(including subjects with diabetes mellitus and/or controlled hypertension) assessed the interaction
between nitroglycerin and tadalafil. Subjects received daily doses of tadalafil 20 mg or matching
placebo for 7 days and then were given a single dose of 0.4 mg sublingual nitroglycerin (NTG) at pre–
specified timepoints following their last dose of tadalafil (2, 4, 8, 24, 48, 72, and 96 hours after
tadalafil). A significant interaction between tadalafil and NTG was observed at each timepoint up to and
including 24 hours. At 48 hours, by most hemodynamic measures, the interaction between tadalafil and
NTG was not observed, although a few more tadalafil subjects compared to placebo experienced
greater blood–pressure lowering effects at this timepoint. After 48 hours, the interaction was not
detectable [see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS].
Effects On Blood Pressure
Tadalafil 20 mg administered to healthy male subjects produced no significant difference compared to
placebo in supine systolic and diastolic blood pressure (difference in the mean maximal decrease of
1.6/0.8 mm Hg, respectively) and in standing systolic and diastolic blood pressure (difference in the
mean maximal decrease of 0.2/4.6 mm Hg, respectively). In addition, there was no significant effect on
heart rate.
Effects On Blood Pressure When Administered With Antihypertensives
Amlodipine
A study assessed the interaction between amlodipine (5 mg daily) and tadalafil 10 mg.
There was no effect of tadalafil on amlodipine blood levels and no effect of amlodipine on tadalafil
blood levels. The mean reduction in supine systolic/diastolic blood pressure because of tadalafil 10 mg
in subjects taking amlodipine was 3/2 mm Hg, compared to placebo. In a similar study using tadalafil 20
mg, there were no clinically significant differences between tadalafil and placebo in subjects taking
amlodipine.
Angiotensin II receptor blockers (with and without other antihypertensives)
A study assessed the interaction between angiotensin II receptor blockers and tadalafil 20 mg. Subjects in the study were
taking any marketed angiotensin II receptor blocker, either alone, as a component of a combination
product, or as part of a multiple antihypertensive regimen. Following dosing, ambulatory measurements
of blood pressure revealed differences between tadalafil and placebo of 8/4 mm Hg in
systolic/diastolic blood pressure.
Bendroflumethiazide
A study assessed the interaction between bendroflumethiazide (2.5 mg daily) and
tadalafil 10 mg. Following dosing, the mean reduction in supine systolic/diastolic blood pressure
because of tadalafil 10 mg in subjects taking bendroflumethiazide was 6/4 mm Hg, compared to placebo.
Enalapril — A study assessed the interaction between enalapril (10 to 20 mg daily) and tadalafil 10 mg.
Following dosing, the mean reduction in supine systolic/diastolic blood pressure because of tadalafil
10 mg in subjects taking enalapril was 4/1 mm Hg, compared to placebo.
Metoprolol
A study assessed the interaction between sustained–release metoprolol (25 to 200 mg
daily) and tadalafil 10 mg. Following dosing, the mean reduction in supine systolic/diastolic blood
pressure because of tadalafil 10 mg in subjects taking metoprolol was 5/3 mm Hg, compared to placebo.
Effects On Blood Pressure When Administered With Alcohol
Alcohol and PDE5 inhibitors, including tadalafil, are mild systemic vasodilators. The interaction of
tadalafil with alcohol was evaluated in three clinical pharmacology studies. In two of these, alcohol
was administered at a dose of 0.7 g/kg, which is equivalent to approximately 6 ounces of 80–proof
vodka in an 80–kg male, and tadalafil was administered at a dose of 10 mg in one study and 20 mg in
another. In both these studies, all patients imbibed the entire alcohol dose within 10 minutes of starting.
In one of these two studies, blood alcohol levels of 0.08% were confirmed. In these two studies, more
patients had clinically significant decreases in blood pressure on the combination of tadalafil and
alcohol as compared to alcohol alone. Some subjects reported postural dizziness, and orthostatic
hypotension was observed in some subjects. When tadalafil 20 mg was administered with a lower dose
of alcohol (0.6 g/kg, which is equivalent to approximately 4 ounces of 80–proof vodka, administered in
less than 10 minutes), orthostatic hypotension was not observed, dizziness occurred with similar
frequency to alcohol alone, and the hypotensive effects of alcohol were not potentiated.
Tadalafil did not affect alcohol plasma concentrations and alcohol did not affect tadalafil plasma
concentrations.
Effects On Blood Pressure When Administered With Alpha-Blockers
Alpha-blockers and PDE5 inhibitors, including tadalafil, are systemic vasodilators. In subjects
receiving concomitant tadalafil (20 mg single dose) and doxazosin (8 mg daily), an alpha-1 adrenergic
receptor blocker, there was an augmentation of the blood pressure–lowering effect of doxazosin. This
effect was still present at 12 hours postdose and had generally disappeared at 24 hours. The number of
subjects with potentially clinically significant standing–blood– pressure decreases was greater for the
combination.
An additional study was performed with tadalafil (20 mg single dose) and doxazosin (4 and 8 mg daily)
using ambulatory blood pressure monitoring. The augmentation appeared unrelated to dosing times and
resulted in a greater number of outliers for the combination than had been observed in the previous
study. Both of these studies had some symptomatology associated with these blood pressure changes.
A further study was carried out with doxazosin (up to 4 mg daily) added to tadalafil (5 mg daily) and
there was again an augmentation of response. In this clinical pharmacology study there were symptoms
associated with the decrease in blood pressure, including syncope.
An interaction study with tadalafil (20 mg single dose) and alfuzosin, also an alpha-1 adrenergic
receptor blocker, showed no clinically significant effect on blood pressure.
In two clinical pharmacology studies in healthy volunteers, tadalafil (5 mg daily, and 10 mg and 20 mg
single dose) had no clinically significant effect on blood pressure changes because of tamsulosin, a
selective alpha-1a adrenergic receptor blocking agent.
Effects On Cardiac Electrophysiology
The effect of a single 100 mg dose of tadalafil (2.5 times the recommended dose) on the QT interval
was evaluated at the time of peak tadalafil concentration in a randomized, double–blinded, placebo, and
active–controlled (intravenous ibutilide) crossover study in 90 healthy males aged 18 to 53 years. The
mean change in QTc (Fridericia QT correction) for tadalafil, relative to placebo, was 3.5 milliseconds
(two–sided 90% CI = 1.9, 5.1). The mean change in QTc (Individual QT correction) for tadalafil,
relative to placebo, was 2.8 milliseconds (two–sided 90% CI = 1.2, 4.4). In this study, the mean increase
in heart rate associated with a 100 mg dose of tadalafil compared to placebo was 3.1 beats per minute.
Effects On Exercise Stress Testing
The effects of tadalafil on cardiac function, hemodynamics, and exercise tolerance were investigated in
a single clinical pharmacology study. In this blinded crossover trial, 23 subjects with stable coronary
artery disease and evidence of exercise–induced cardiac ischemia were enrolled. The primary endpoint
was time to cardiac ischemia. The mean difference in total exercise time was 3 seconds (tadalafil 10 mg
minus placebo), which represented no clinically meaningful difference. Further statistical analysis
demonstrated that tadalafil was similar to placebo with respect to time to ischemia. Of note, in this study,
in some subjects who received tadalafil followed by sublingual nitroglycerin in the post–exercise
period, clinically significant reductions in blood pressure were observed, consistent with the
augmentation by tadalafil of the blood–pressure–lowering effects of nitrates.
Effects On Vision
Single oral doses of PDE inhibitors have demonstrated transient dose-related impairment of color
discrimination (blue/green), using the Farnsworth–Munsell 100–hue test, with peak effects near the time
of peak plasma levels. This finding is consistent with the inhibition of PDE6, which is involved in
phototransduction in the retina. In a study to assess the effects of a single dose of tadalafil 40 mg on
vision (N = 59), no effects were observed on visual acuity, intraocular pressure, or pupillometry.
Across all clinical studies with tadalafil, reports of changes in color vision were rare (< 0.1% of
patients).
Effects On Sperm Characteristics
Three studies were conducted in men to assess the potential effect on sperm characteristics of tadalafil
10 mg (one 6-month study) and 20 mg (one 6-month and one 9-month study) administered daily. There
were no adverse effects on sperm morphology or sperm motility in any of the three studies. In the study
of 10 mg tadalafil for 6 months and the study of 20 mg tadalafil for 9 months, results showed a decrease
in mean sperm concentrations relative to placebo, although these differences were not clinically
meaningful. This effect was not seen in the study of 20 mg tadalafil taken for 6 months. In addition there
was no adverse effect on mean concentrations of reproductive hormones, testosterone, luteinizing
hormone or follicle stimulating hormone with either 10 or 20 mg of tadalafil compared to placebo.
Dose-Response Relationship
Dose-response relationships, between 20 mg and 40 mg, were not observed for 6-minute walk distance
or pulmonary vascular resistance (PVR) in subjects with PAH in the placebo-controlled study. Median
change from baseline in 6-minute walk distance was 32 meters and 35 meters at 16 weeks in subjects
receiving 20 mg and 40 mg daily, respectively. Mean change from baseline PVR was -254
dynes sec cm-5 and -209 dynes sec cm-5 at 16 weeks in patients receiving 20 mg and 40 mg daily,
respectively.
Pharmacokinetics
Over a dose range of 2.5 to 20 mg, tadalafil exposure (AUC) increases proportionally with dose in
healthy subjects. In PAH patients administered between 20 and 40 mg of tadalafil, an approximately 1.5-
fold greater AUC was observed indicating a less than proportional increase in exposure over the entire
dose range of 2.5 to 40 mg. During tadalafil 20 and 40 mg once daily dosing, steady-state plasma
concentrations were attained within 5 days, and exposure was approximately 1.3-fold higher than after a
single dose.
Absorption
After single oral-dose administration, the maximum observed plasma concentration
(Cmax ) of tadalafil is achieved between 2 and 8 hours (median time of 4 hours). Absolute bioavailability
of tadalafil following oral dosing has not been determined.
The rate and extent of absorption of tadalafil is not influenced by food; thus ALYQ™ may be taken with
or without food.
Distribution
The mean apparent volume of distribution following oral administration is approximately
77 L, indicating that tadalafil is distributed into tissues. At therapeutic concentrations, 94% of tadalafil
in plasma is bound to proteins.
Metabolism
Tadalafil is predominantly metabolized by CYP3A to a catechol metabolite. The
catechol metabolite undergoes extensive methylation and glucuronidation to form the methylcatechol
and methylcatechol glucuronide conjugate, respectively. The major circulating metabolite is the
methylcatechol glucuronide. Methylcatechol concentrations are less than 10% of glucuronide
concentrations. In vitro data suggests that metabolites are not expected to be pharmacologically active at
observed metabolite concentrations.
Elimination
Following 40 mg, the mean oral clearance for tadalafil is 3.4 L/hr and the mean terminal
half-life is 15 hours in healthy subjects. In patients with pulmonary hypertension not receiving
concomitant bosentan, the mean oral clearance for tadalafil is 1.6 L/hr, and the mean terminal half-life is
35 hours. Tadalafil is excreted predominantly as metabolites, mainly in the feces (approximately 61% of
the dose) and to a lesser extent in the urine (approximately 36% of the dose).
Population Pharmacokinetics
In patients with pulmonary hypertension not receiving concomitant
bosentan, the average tadalafil exposure at steady-state following 40 mg was 26% higher when
compared to those of healthy volunteers. The results suggest a lower clearance of tadalafil in patients
with pulmonary hypertension compared to healthy volunteers.
Geriatric Patients
In healthy male elderly subjects (65 years or over) after a 10 mg dose, a lower oral clearance of
tadalafil, resulting in 25% higher exposure (AUC) with no effect on Cmax was observed relative to that
in healthy subjects 19 to 45 years of age.
Renal Impairment
In clinical pharmacology studies using single-dose tadalafil (5 to 10 mg), tadalafil exposure (AUC)
doubled in subjects with mild (creatinine clearance 51 to 80 mL/min) or moderate (creatinine clearance
31 to 50 mL/min) renal impairment. In subjects with end-stage renal disease on hemodialysis, there was a
two-fold increase in Cmax and 2.7- to 4.1-fold increase in AUC following single-dose administration of
10 or 20 mg tadalafil, respectively. Exposure to total methylcatechol (unconjugated plus glucuronide)
was 2- to 4-fold higher in subjects with renal impairment, compared to those with normal renal function.
Hemodialysis (performed between 24 and 30 hours post-dose) contributed negligibly to tadalafil or
metabolite elimination [see DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS].
Hepatic Impairment
In clinical pharmacology studies, tadalafil exposure (AUC) in subjects with mild or moderate hepatic
impairment (Child-Pugh Class A or B) was comparable to exposure in healthy subjects when a dose of
10 mg was administered. There are no available data for doses higher than 10 mg of tadalafil in patients
with hepatic impairment. Insufficient data are available for subjects with severe hepatic impairment
(Child-Pugh Class C) [see DOSAGE AND ADMINISTRATION and WARNINGS AND PRECAUTIONS].
Patients With Diabetes Mellitus
In male patients with diabetes mellitus after a 10 mg tadalafil dose, exposure (AUC) was reduced
approximately 19% and Cmax was 5% lower than that observed in healthy subjects. No dose adjustment
is warranted.
Race
Pharmacokinetic studies have included subjects from different ethnic groups, and no differences in the
typical exposure to tadalafil have been identified. No dose adjustment is warranted.
Gender
In healthy female and male subjects following single and multiple-doses of tadalafil, no clinically
relevant differences in exposure (AUC and Cmax ) were observed. No dose adjustment is warranted.
Drug Interaction Studies
Tadalafil is a substrate of and predominantly metabolized by CYP3A. Drugs that inhibit CYP3A can
increase tadalafil exposure.
Ritonavir
Ritonavir (500 mg or 600 mg twice daily at steady state), an inhibitor of CYP3A, CYP2C9, CYP2C19,
and CYP2D6, increased tadalafil 20–mg single-dose exposure (AUC) by 32% with a 30% reduction in
Cmax , relative to the values for tadalafil 20 mg alone. Ritonavir (200 mg twice daily), increased
tadalafil 20–mg single-dose exposure (AUC) by 124% with no change in C , relative to the values
for tadalafil 20 mg alone. Ritonavir inhibits and induces CYP3A, the enzyme involved in the metabolism
of tadalafil, in a time-dependent manner. The results suggest the initial inhibitory effect of ritonavir on
CYP3A may be mitigated by a more slowly evolving induction effect so that after about 1 week of
ritonavir twice daily, the exposure of tadalafil is similar in the presence of and absence of ritonavir [see DOSAGE AND ADMINISTRATION , WARNINGS AND PRECAUTIONS , and DRUG INTERACTIONS]. Although
specific interactions have not been studied, other HIV protease inhibitors would likely increase
tadalafil exposure.
Other Cytochrome P450 Inhibitors
CYP3A (e.g., ketoconazole)
Ketoconazole (400 mg daily), a selective and potent inhibitor of CYP3A,
increased tadalafil 20 mg single-dose exposure (AUC) by 312% and Cmax by 22%, relative to the
values for tadalafil 20 mg alone. Ketoconazole (200 mg daily) increased tadalafil 10–mg single-dose
exposure (AUC) by 107% and Cmax by 15%, relative to the values for tadalafil 10 mg alone.
Although specific interactions have not been studied, other CYP3A inhibitors, such as erythromycin,
itraconazole, and grapefruit juice, would likely increase tadalafil exposure.
Cytochrome P450 Inducers
CYP3A (e.g., rifampin, bosentan)
Rifampin (600 mg daily), a CYP3A inducer, reduced tadalafil 10 mg
single-dose exposure (AUC) by 88% and Cmax by 46%, relative to the values for tadalafil 10 mg alone.
Bosentan (125 mg twice daily), a substrate of CYP2C9 and CYP3A and a moderate inducer of CYP3A,
CYP2C9 and possibly CYP2C19, reduced tadalafil (40 mg once per day) systemic exposure by 42% and
C by 27% following multiple-dose coadministration.
Although specific interactions have not been studied, other CYP3A inducers, such as carbamazepine,
phenytoin, and phenobarbital, would likely decrease tadalafil exposure.
Cytochrome P450 Substrates
Tadalafil is not expected to cause clinically significant inhibition or
induction of the clearance of drugs metabolized by cytochrome P450 (CYP) isoforms.
CYP1A2 (e.g., theophylline)
Tadalafil (10 mg once per day) had no significant effect on the
pharmacokinetics of theophylline. When tadalafil was administered to subjects taking theophylline, a
small augmentation (3 beats per minute) of the increase in heart rate associated with theophylline was
observed.
CYP2C9 (e.g., warfarin)
Tadalafil (10 mg and 20 mg once per day) had no significant effect on
exposure (AUC) to S–warfarin or R–warfarin, nor did tadalafil affect changes in prothrombin time
induced by warfarin.
CYP3A (e.g., midazolam, lovastatin or bosentan)
Tadalafil (10 mg and 20 mg once per day) had no
significant effect on exposure (AUC) to midazolam or lovastatin. Tadalafil (40 mg once per day) had no
clinically significant effect on exposure (AUC and Cmax ) of bosentan, a substrate of CYP2C9 and
CYP3A, or its metabolites.
Aspirin
Tadalafil (10 mg and 20 mg once per day) did not potentiate the increase in bleeding time
caused by aspirin.
P-Glycoprotein (E.g., Digoxin)
Coadministration of tadalafil (40 mg once per day) for 10 days did not
have a significant effect on the steady-state pharmacokinetics of digoxin (0.25 mg/day) in healthy
subjects.
Combined Oral Contraceptives
At steady-state, tadalafil (40 mg once per day) increased ethinyl
estradiol exposure (AUC) by 26% and Cmax by 70% relative to oral contraceptive administered with
placebo. There was no significant effect of tadalafil on levonorgestrel.
Antacids
Simultaneous administration of an antacid (magnesium hydroxide/aluminum hydroxide) and
tadalafil (10 mg) reduced the apparent rate of absorption of tadalafil without altering exposure (AUC) to
tadalafil.
H2 Antagonists (E.g., Nizatidine)
An increase in gastric pH resulting from administration of nizatidine
had no significant effect on tadalafil (10 mg) pharmacokinetics.
Animal Toxicology And/Or Pharmacology
Animal studies showed vascular inflammation in tadalafil–treated mice, rats, and dogs. In mice and rats,
lymphoid necrosis and hemorrhage were seen in the spleen, thymus, and mesenteric lymph nodes at
unbound tadalafil exposure of 1– to 17–fold the human exposure (AUCs) at the MRHD of 40 mg. In
dogs, an increased incidence of disseminated arteritis was observed in 1– and 6-month studies at
unbound tadalafil exposure of 0.5– to 38–fold the human exposure (AUC) at the MRHD of 40 mg. In a
12–month dog study, no disseminated arteritis was observed, but 2 dogs exhibited marked decreases in
white blood cells (neutrophils) and moderate decreases in platelets with inflammatory signs at unbound
tadalafil exposures of approximately 4– to 10–fold the human exposure at the MRHD of 40 mg. The
abnormal blood–cell findings were reversible within 2 weeks upon removal of the drug.
Clinical Studies
ALYQ™ For Pulmonary Arterial Hypertension
A randomized, double-blind, 16 week placebo-controlled study was conducted in 405 patients with
pulmonary arterial hypertension, defined as a resting mean pulmonary artery pressure (mPAP) ≥25 mm
Hg, pulmonary capillary wedge pressure (PCWP) ≤ 15 mm Hg, and pulmonary vascular resistance
(PVR) ≥3 Wood units via right heart catheterization. Allowed background therapy included bosentan
(maintenance dosing up to 125 mg twice daily) and chronic anticoagulation. The use of prostacyclin or
analogue, L–arginine, phosphodiesterase inhibitor, or other chronic PAH medications were not
permitted.
Subjects were randomly assigned to 1 of 5 treatment groups (tadalafil 2.5, 10, 20, 40 mg, or placebo) in
a 1:1:1:1:1 ratio. Subjects had to be at least 12 years of age and had a diagnosis of PAH that was
idiopathic, heritable, related to connective tissue disease, anorexigen use, human immunodeficiency
virus (HIV) infection, associated with an atrial-septal defect, or associated with surgical repair of a
congenital systemic-to-pulmonary shunt of least 1 year in duration (for example, ventricular septal
defect, patent ductus arteriosus). Patients with a history of left-sided heart disease, severe renal
insufficiency, or pulmonary hypertension related to conditions other than specified in the inclusion
criteria were not eligible for enrollment.
The mean age of all subjects was 54 years (range 14 to 90 years) with the majority of subjects being
Caucasian (81%) and female (78%). PAH etiologies were predominantly idiopathic or heritable PAH
(61%) and related to connective tissue disease (23%). More than half (53%) of the subjects in the study
were receiving concomitant bosentan therapy. The majority of subjects had a World Health Organization
(WHO) Functional Class III (65%) or II (32%). The mean baseline 6-minute walk distance (6-MWD) was
343 meters. Of the 405 subjects, 341 completed the study.
The primary efficacy endpoint was the change from baseline at week 16 in 6-MWD (see Figure 1). In
the tadalafil 40 mg treatment group, the placebo-adjusted mean change increase in 6-MWD was 33
meters (95% C.I. 15 to 50 meters; p = 0.0004). The improvement in 6-MWD was apparent at 8 weeks of
treatment and then maintained at week 12 and week 16.
Figure 1: 6-Minute Walk Distance (meters) Mean Change from Baseline, with 95% Confidence Intervals
Placebo-adjusted changes in 6-MWD at 16 weeks were evaluated in subgroups (see Figure 2). In
patients taking only ALYQ™ 40 mg (i.e., without concomitant bosentan), the placebo-adjusted mean
change in 6-MWD was 44 meters. In patients taking tadalafil 40 mg and concomitant bosentan therapy,
the placebo adjusted mean change in 6-MWD was 23 meters.
Figure 2: Placebo-adjusted Mean Change in 6-Minute Walk Distance (meters) of ALYQ™ 4 0 mg , with
95% Confidence Intervals
There was less clinical worsening (defined as death, lung transplantation, atrial septostomy,
hospitalization because of worsening PAH, initiation of new PAH therapy [prostacyclin or analog,
endothelin receptor antagonist, PDE5 inhibitor], or worsening WHO functional class) in the ALYQ™
40 mg group compared to the placebo group and the groups that used lower doses of ALYQ™.
Table 2: Number (percent) with Clinical Worseninga
|
|
Tadalafil |
Placebo |
2.5 mg |
10 mg |
20 mg |
40 mg |
N = 82 |
N = 82 |
N = 80 |
N = 82 |
N = 79 |
Total with clinical
Worsening |
13 (16) |
10 (12) |
7 (9) |
8 (10) |
4 (5) |
Death |
1 |
0 |
1 |
0 |
0 |
Hos pitalization for
Worsening PAH |
2 |
2 |
3 |
0 |
1 |
New PAH therapy |
0 |
1 |
0 |
2 |
1 |
Worsening WHO
class |
11 |
10 |
6 |
3 |
3 |
a Subjects may be counted in more than one category |
The Kaplan-Meier plot of times to clinical worsening is shown below in Figure 3.
Figure 3: Kaplan-Meier Plot of Time to Clinical Worsening
Patients (N = 357) from the placebo-controlled study entered a long-term extension study. Of these, 311
patients have been treated with tadalafil for at least 6 months and 182 for 1 year (median exposure 356
days; range 2 days to 415 days). The survival rate in the extension study was 96.5 per 100 patient years.
Without a control group, these data must be interpreted cautiously.
Reproductive Toxicology Studies
Reproduction studies have been performed in rats and mice at exposures up to 17 times the MRHD of
40 mg and have revealed no evidence of impaired fertility or harm to the fetus because of tadalafil. In
addition, there was no evidence of teratogenicity, embryotoxicity, or fetotoxicity when tadalafil was
given to pregnant rats or mice at exposures up to 7 times the MRHD during the period of major organ
development.
In a rat prenatal and postnatal development study at doses of 60, 200, and 1000 mg/kg, a reduction in
postnatal survival of pups was observed. The no-observed-effect-level (NOEL) for maternal toxicity
was 200 mg/kg/day and for developmental toxicity was 30 mg/kg/day. This gives approximately 8- and
5-fold exposure multiples, respectively, of the human AUC for the MRHD of 40 mg. Tadalafil and/or
its metabolites cross the placenta, resulting in fetal exposure in rats.
Tadalafil and/or its metabolites were secreted into the milk in lactating rats at concentrations
approximately 2.4–fold greater than found in the plasma.