CLINICAL PHARMACOLOGY
The involvement of low-density lipoprotein cholesterol
(LDL-C) in atherogenesis has been welldocumented in clinical and pathological studies,
as well as in many animal experiments. Epidemiological and clinical studies
have established that high LDL-C and low high-density lipoprotein cholesterol
(HDLC) are both associated with coronary heart disease. However, the risk of
developing coronary heart disease is continuous and graded over the range of
cholesterol levels and many coronary events do occur in patients with total
cholesterol (total-C) and LDL-C in the lower end of this range.
MEVACOR has been shown to reduce both normal and elevated
LDL-C concentrations. LDL is formed from very low-density lipoprotein (VLDL)
and is catabolized predominantly by the high affinity LDL receptor. The
mechanism of the LDL-lowering effect of MEVACOR may involve both reduction of
VLDL-C concentration, and induction of the LDL receptor, leading to reduced
production and/or increased catabolism of LDL-C. Apolipoprotein B also falls
substantially during treatment with MEVACOR. Since each LDL particle contains
one molecule of apolipoprotein B, and since little apolipoprotein B is found in
other lipoproteins, this strongly suggests that MEVACOR does not merely cause
cholesterol to be lost from LDL, but also reduces the concentration of
circulating LDL particles. In addition, MEVACOR can produce increases of variable
magnitude in HDL-C, and modestly reduces VLDL-C and plasma triglycerides (TG)
(see Tables II-IV under Clinical Studies). The effects of MEVACOR on
Lp(a), fibrinogen, and certain other independent biochemical risk markers for
coronary heart disease are unknown.
MEVACOR is a specific inhibitor of HMG-CoA reductase, the
enzyme which catalyzes the conversion of HMG-CoA to mevalonate. The conversion
of HMG-CoA to mevalonate is an early step in the biosynthetic pathway for
cholesterol.
Pharmacokinetics
Lovastatin is a lactone which is readily hydrolyzed in
vivo to the corresponding α-hydroxyacid, a strong inhibitor of HMG-CoA
reductase. Inhibition of HMG-CoA reductase is the basis for an assay in pharmacokinetic
studies of the α-hydroxyacid metabolites (active inhibitors) and,
following base hydrolysis, active plus latent inhibitors (total inhibitors) in
plasma following administration of lovastatin.
Following an oral dose of 14C-labeled lovastatin in man,
10% of the dose was excreted in urine and 83% in feces. The latter represents
absorbed drug equivalents excreted in bile, as well as any unabsorbed drug.
Plasma concentrations of total radioactivity (lovastatin plus 14C-metabolites)
peaked at 2 hours and declined rapidly to about 10% of peak by 24 hours postdose.
Absorption of lovastatin, estimated relative to an intravenous reference dose,
in each of four animal species tested, averaged about 30% of an oral dose. In
animal studies, after oral dosing, lovastatin had high selectivity for the
liver, where it achieved substantially higher concentrations than in non-target
tissues. Lovastatin undergoes extensive first-pass extraction in the liver, its
primary site of action, with subsequent excretion of drug equivalents in the
bile. As a consequence of extensive hepatic extraction of lovastatin, the
availability of drug to the general circulation is low and variable. In a
single dose study in four hypercholesterolemic patients, it was estimated that
less than 5% of an oral dose of lovastatin reaches the general circulation as
active inhibitors. Following administration of lovastatin tablets the
coefficient of variation, based on between-subject variability, was
approximately 40% for the area under the curve (AUC) of total inhibitory activity
in the general circulation.
Both lovastatin and its α-hydroxyacid metabolite are
highly bound ( > 95%) to human plasma proteins. Animal studies demonstrated
that lovastatin crosses the blood-brain and placental barriers.
The major active metabolites present in human plasma are
the α-hydroxyacid of lovastatin, its 6'-hydroxy
derivative, and two additional metabolites. Peak plasma concentrations of both
active and total inhibitors were attained within 2 to 4 hours of dose
administration. While the recommended therapeutic dose range is 10 to 80 mg/day,
linearity of inhibitory activity in the general circulation was established by a
single dose study employing lovastatin tablet dosages from 60 to as high as 120
mg. With a once-a-day dosing regimen, plasma concentrations of total inhibitors
over a dosing interval achieved a steady state between the second and third
days of therapy and were about 1.5 times those following a single dose. When
lovastatin was given under fasting conditions, plasma concentrations of total
inhibitors were on average about two-thirds those found when lovastatin was
administered immediately after a standard test meal.
In a study of patients with severe renal insufficiency
(creatinine clearance 10-30 mL/min), the plasma concentrations of total
inhibitors after a single dose of lovastatin were approximately two-fold higher
than those in healthy volunteers.
In a study including 16 elderly patients between 70-78
years of age who received MEVACOR 80 mg/day, the mean plasma level of HMG-CoA
reductase inhibitory activity was increased approximately 45% compared with 18
patients between 18-30 years of age (see PRECAUTIONS, Geriatric Use).
Although the mechanism is not fully understood,
cyclosporine has been shown to increase the AUC of HMG-CoA reductase
inhibitors. The increase in AUC for lovastatin and lovastatin acid is
presumably due, in part, to inhibition of CYP3A4.
The risk of myopathy is increased by high levels of
HMG-CoA reductase inhibitory activity in plasma. Strong inhibitors of CYP3A4
can raise the plasma levels of HMG-CoA reductase inhibitory activity and increase
the risk of myopathy (see WARNINGS, Myopathy/Rhabdomyolysis and PRECAUTIONS: DRUG INTERACTIONS).
Lovastatin is a substrate for cytochrome P450 isoform 3A4
(CYP3A4) (see PRECAUTIONS: DRUG INTERACTIONS). Grapefruit juice
contains one or more components that inhibit CYP3A4 and can increase the plasma
concentrations of drugs metabolized by CYP3A4. In one study1, 10
subjects consumed 200 mL of double-strength grapefruit juice (one can of frozen
concentrate diluted with one rather than 3 cans of water) three times daily for
2 days and an additional 200 mL double-strength grapefruit juice together with
and 30 and 90 minutes following a single dose of 80 mg lovastatin on the third
day. This regimen of grapefruit juice resulted in a mean increase in the serum
concentration of lovastatin and its α-hydroxyacid metabolite (as measured
by the area under the concentration-time curve) of 15-fold and 5-fold, respectively
[as measured using a chemical assay — high performance liquid chromatography].
In a second study, 15 subjects consumed one 8 oz glass of single-strength
grapefruit juice (one can of frozen concentrate diluted with 3 cans of water)
with breakfast for 3 consecutive days and a single dose of 40 mg lovastatin in
the evening of the third day. This regimen of grapefruit juice resulted in a
mean increase in the plasma concentration (as measured by the area under the
concentration-time curve) of active and total HMG-CoA reductase inhibitory
activity [using an enzyme inhibition assay both before (for active inhibitors)
and after (for total inhibitors) base hydrolysis] of 1.34-fold and 1.36-fold,
respectively, and of lovastatin and its α-hydroxyacid metabolite [measured
using a chemical assay — liquid chromatography/tandem mass spectrometry —
different from that used in the first1 study] of 1.94-fold and 1.57-fold,
respectively. The effect of amounts of grapefruit juice between those used in
these two studies on lovastatin pharmacokinetics has not been studied.
TABLE I: The Effect of Other Drugs on Lovastatin
Exposure When Both Were Co-administered
|
Number of Subjects |
Dosing of Coadministered Drug or Grapefruit Juice |
Dosing of Lovastatin |
AUC Ratio* (with / without coadministered drug) No Effect = 1.00 |
Lovastatin |
Lovastatin acid† |
Gemfibrozil |
11 |
600 mg BID for 3 days |
40 mg |
0.96 |
2.80 |
Itraconazole* |
12 |
200 mg QD for 4 days |
40 mg on Day 4 |
> 36§ |
22 |
|
10 |
100 mg QD for 4 days |
40 mg on Day 4 |
> 14.8§ |
15.4 |
Grapefruit Juice1¶(high dose) |
10 |
200 mL of double-strength TID# |
80 mg single dose |
15.3 |
5.0 |
Grapefruit Juice¶ (low dose) |
16 |
8 oz (about 250 mL) of single-strengthÞ for 4 days |
40 mg single dose |
1.94 |
1.57 |
Cyclosporine |
16 |
Not describedβ |
10 mg QD for 10 days |
5- to 8-fold |
NDa |
|
Number of Subjects |
Dosing of Coadministered Drug or Grapefruit Juice |
Dosing of Lovastatin |
AUC Ratio* (with / without coadministered drug)
No Effect = 1.00 |
Total Lovastatin acide |
Diltiazem |
10 |
120 mg BID for 14 days |
20 mg |
3.57e |
* Results based on a chemical assay.
† Lovastatin acid refers to the α-hydroxyacid of lovastatin.
‡ The mean total AUC of lovastatin without itraconazole phase could not be
determined accurately. Results could be representative of strong CYP3A4
inhibitors such as ketoconazole, posaconazole, clarithromycin, telithromycin,
HIV protease inhibitors, and nefazodone.
§ Estimated minimum change.
¶ The effect of amounts of grapefruit juice between those used in these two
studies on lovastatin pharmacokinetics has not been studied.
# Double-strength: one can of frozen concentrate diluted with one can of water.
Grapefruit juice was administered TID for 2 days, and 200 mL together with
single dose lovastatin and 30 and 90 minutes following single dose lovastatin
on Day 3.
Þ Single-strength: one can of frozen concentrate diluted with 3 cans of water.
Grapefruit juice was administered with breakfast for 3 days, and lovastatin was
administered in the evening on Day 3.
β Cyclosporine-treated patients with psoriasis or post kidney or heart
transplant patients with stable graft function, transplanted at least 9 months
prior to study.
a ND = Analyte not determined.
e Lactone converted to acid by hydrolysis prior to analysis. Figure represents
total unmetabolized acid and lactone. |
Clinical Studies in Adults
MEVACOR has been shown to be highly effective in reducing
total-C and LDL-C in heterozygous familial and non-familial forms of primary
hypercholesterolemia and in mixed hyperlipidemia. A marked response was seen
within 2 weeks, and the maximum therapeutic response occurred within 4-6 weeks.
The response was maintained during continuation of therapy. Single daily doses
given in the evening were more effective than the same dose given in the
morning, perhaps because cholesterol is synthesized mainly at night.
In multicenter, double-blind studies in patients with
familial or non-familial hypercholesterolemia, MEVACOR, administered in doses
ranging from 10 mg q.p.m. to 40 mg b.i.d., was compared to placebo. MEVACOR
consistently and significantly decreased plasma total-C, LDL-C, total-C/HDL-C
ratio and LDLC/ HDL-C ratio. In addition, MEVACOR produced increases of
variable magnitude in HDL-C, and modestly decreased VLDL-C and plasma TG (see
Tables II through IV for dose response results). The results of a study in
patients with primary hypercholesterolemia are presented in Table II.
TABLE II: MEVACOR vs. Placebo (Mean Percent Change
from Baseline After 6 Weeks)
DOSAGE |
N |
TOTAL-C |
LDL-C |
HDL-C |
LDL-C/ HDL-C |
TOTAL-C/ HDL-C |
TG. |
Placebo |
33 |
-2 |
-1 |
-1 |
0 |
+1 |
+9 |
MEVACOR |
|
|
|
|
|
|
|
10 mg q.p.m. |
33 |
-16 |
-21 |
+5 |
-24 |
-19 |
-10 |
20 mg q.p.m. |
33 |
-19 |
-27 |
+6 |
-30 |
-23 |
+9 |
10 mg b.i.d. |
32 |
-19 |
-28 |
+8 |
-33 |
-25 |
-7 |
40 mg q.p.m. |
33 |
-22 |
-31 |
+5 |
-33 |
-25 |
-8 |
20 mg b.i.d. |
36 |
-24 |
-32 |
+2 |
-32 |
-24 |
-6 |
MEVACOR was compared to cholestyramine in a randomized
open parallel study. The study was performed with patients with
hypercholesterolemia who were at high risk of myocardial infarction. Summary
results are presented in Table III.
TABLE III: MEVACOR vs. Cholestyramine (Percent Change
from Baseline After 12 Weeks)
TREATMENT |
N |
TOTAL-C (mean) |
LDL-C (mean) |
HDL-C (mean) |
LDL-C/ HDL-C (mean) |
TOTAL-C/ HDL-C (mean) |
VLDL-C (median) |
TG. (mean) |
MEVACOR |
20 mg b.i.d. |
85 |
-27 |
-32 |
+9 |
-36 |
-31 |
-34 |
-21 |
40 mg b.i.d. |
88 |
-34 |
-42 |
+8 |
-44 |
-37 |
-31 |
-27 |
Cholestyramine |
12 g b.i.d. |
88 |
-17 |
-23 |
+8 |
-27 |
-21 |
+2 |
+ 11 |
MEVACOR was studied in controlled trials in hypercholesterolemic
patients with well-controlled noninsulin dependent diabetes mellitus with
normal renal function. The effect of MEVACOR on lipids and lipoproteins and the
safety profile of MEVACOR were similar to that demonstrated in studies in nondiabetics.
MEVACOR had no clinically important effect on glycemic control or on the dose requirement
of oral hypoglycemic agents.
Expanded Clinical Evaluation of Lovastatin (EXCEL) Study
MEVACOR was compared to placebo in 8,245 patients with
hypercholesterolemia (total-C 240-300 mg/dL [6.2 mmol/L - 7.6 mmol/L], LDL-C
> 160 mg/dL [4.1 mmol/L]) in the randomized, double-blind, parallel, 48-week
EXCEL study. All changes in the lipid measurements (Table IV) in MEVACOR
treated patients were dose-related and significantly different from placebo (p ≤ 0.001).
These results were sustained throughout the study.
TABLE IV: MEVACOR vs. Placebo (Percent Change from
Baseline — Average Values Between Weeks 12 and 48)
DOSAGE |
N** |
TOTAL-C (mean) |
LDL-C (mean) |
HDL-C (mean) |
LDL-C/HDL-C (mean) |
TOTAL-C/HDL-C (mean) |
TG. (median) |
Placebo |
1663 |
+0.7 |
+0.4 |
+2.0 |
+0.2 |
+0.6 |
+4 |
MEVACOR |
|
|
|
|
|
|
|
20 mg q.p.m. |
1642 |
-17 |
-24 |
+6.6 |
-27 |
-21 |
-10 |
40 mg q.p.m. |
1645 |
-22 |
-30 |
+7.2 |
-34 |
-26 |
-14 |
20 mg b.i.d. |
1646 |
-24 |
-34 |
+8.6 |
-38 |
-29 |
-16 |
40 mg b.i.d. |
1649 |
-29 |
-40 |
+9.5 |
-44 |
-34 |
-19 |
**Patients enrolled |
Air Force/Texas Coronary Atherosclerosis Prevention Study
(AFCAPS/TexCAPS)
The Air Force/Texas Coronary Atherosclerosis Prevention
Study (AFCAPS/TexCAPS), a double-blind, randomized, placebo-controlled, primary
prevention study, demonstrated that treatment with MEVACOR decreased the rate
of acute major coronary events (composite endpoint of myocardial infarction,
unstable angina, and sudden cardiac death) compared with placebo during a
median of 5.1 years of follow-up. Participants were middle-aged and elderly men
(ages 45-73) and women (ages 55-73) without symptomatic cardiovascular disease
with average to moderately elevated total-C and LDL-C, below average HDL-C, and
who were at high risk based on elevated total-C/HDL-C. In addition to age, 63%
of the participants had at least one other risk factor (baseline HDL-C < 35
mg/dL, hypertension, family history, smoking and diabetes).
AFCAPS/TexCAPS enrolled 6,605 participants (5,608 men,
997 women) based on the following lipid entry criteria: total-C range of
180-264 mg/dL, LDL-C range of 130-190 mg/dL, HDL-C of ≤ 45 mg/dL for men
and ≤ 47 mg/dL for women, and TG of ≤ 400 mg/dL. Participants were
treated with standard care, including diet, and either MEVACOR 20-40 mg daily
(n= 3,304) or placebo (n= 3,301). Approximately 50% of the participants treated
with MEVACOR were titrated to 40 mg daily when their LDL-C remained > 110
mg/dL at the 20-mg starting dose.
MEVACOR reduced the risk of a first acute major coronary
event, the primary efficacy endpoint, by 37% (MEVACOR 3.5%, placebo 5.5%;
p < 0.001; Figure 1). A first acute major coronary event was defined as
myocardial infarction (54 participants on MEVACOR, 94 on placebo) or unstable
angina (54 vs. 80) or sudden cardiac death (8 vs. 9). Furthermore, among the
secondary endpoints, MEVACOR reduced the risk of unstable angina by 32% (1.8
vs. 2.6%; p=0.023), of myocardial infarction by 40% (1.7 vs. 2.9%; p=0.002),
and of undergoing coronary revascularization procedures (e.g., coronary artery
bypass grafting or percutaneous transluminal coronary angioplasty) by 33% (3.2
vs. 4.8%; p=0.001). Trends in risk reduction associated with treatment with
MEVACOR were consistent across men and women, smokers and non-smokers,
hypertensives and non-hypertensives, and older and younger participants.
Participants with ≥ 2 risk factors had risk reductions (RR) in both acute
major coronary events (RR 43%) and coronary revascularization procedures (RR
37%). Because there were too few events among those participants with age as
their only risk factor in this study, the effect of MEVACOR on outcomes could
not be adequately assessed in this subgroup.
Figure 1 : Acute Major Coronary Events (Primary
Endpoint)
Atherosclerosis
In the Canadian Coronary Atherosclerosis Intervention
Trial (CCAIT), the effect of therapy with lovastatin on coronary
atherosclerosis was assessed by coronary angiography in hyperlipidemic
patients. In the randomized, double-blind, controlled clinical trial, patients
were treated with conventional measures (usually diet and 325 mg of aspirin
every other day) and either lovastatin 20-80 mg daily or placebo. Angiograms
were evaluated at baseline and at two years by computerized quantitative
coronary angiography (QCA). Lovastatin significantly slowed the progression of
lesions as measured by the mean change per-patient in minimum lumen diameter
(the primary endpoint) and percent diameter stenosis, and decreased the
proportions of patients categorized with disease progression (33% vs. 50%) and
with new lesions (16% vs. 32%).
In a similarly designed trial, the Monitored
Atherosclerosis Regression Study (MARS), patients were treated with diet and
either lovastatin 80 mg daily or placebo. No statistically significant
difference between lovastatin and placebo was seen for the primary endpoint
(mean change per patient in percent diameter stenosis of all lesions), or for
most secondary QCA endpoints. Visual assessment by angiographers who formed a
consensus opinion of overall angiographic change (Global Change Score) was also
a secondary endpoint. By this endpoint, significant slowing of disease was
seen, with regression in 23% of patients treated with lovastatin compared to
11% of placebo patients.
In the Familial Atherosclerosis Treatment Study (FATS),
either lovastatin or niacin in combination with a bile acid sequestrant for 2.5
years in hyperlipidemic subjects significantly reduced the frequency of progression
and increased the frequency of regression of coronary atherosclerotic lesions
by QCA compared to diet and, in some cases, low-dose resin.
The effect of lovastatin on the progression of
atherosclerosis in the coronary arteries has been corroborated by similar
findings in another vasculature. In the Asymptomatic Carotid Artery Progression
Study (ACAPS), the effect of therapy with lovastatin on carotid atherosclerosis
was assessed by B-mode ultrasonography in hyperlipidemic patients with early
carotid lesions and without known coronary heart disease at baseline. In this
double-blind, controlled clinical trial, 919 patients were randomized in a 2 x
2 factorial design to placebo, lovastatin 10-40 mg daily and/or warfarin.
Ultrasonograms of the carotid walls were used to determine the change per
patient from baseline to three years in mean maximum intimal-medial thickness
(IMT) of 12 measured segments. There was a significant regression of carotid
lesions in patients receiving lovastatin alone compared to those receiving
placebo alone (p=0.001). The predictive value of changes in IMT for stroke has
not yet been established. In the lovastatin group there was a significant
reduction in the number of patients with major cardiovascular events relative
to the placebo group (5 vs. 14) and a significant reduction in all-cause
mortality (1 vs. 8).
Eye
There was a high prevalence of baseline lenticular
opacities in the patient population included in the early clinical trials with
lovastatin. During these trials the appearance of new opacities was noted in
both the lovastatin and placebo groups. There was no clinically significant
change in visual acuity in the patients who had new opacities reported nor was
any patient, including those with opacities noted at baseline, discontinued
from therapy because of a decrease in visual acuity.
A three-year, double-blind, placebo-controlled study in
hypercholesterolemic patients to assess the effect of lovastatin on the human
lens demonstrated that there were no clinically or statistically significant differences
between the lovastatin and placebo groups in the incidence, type or progression
of lenticular opacities. There are no controlled clinical data assessing the
lens available for treatment beyond three years.
Clinical Studies in Adolescent Patients
Efficacy of Lovastatin in Adolescent Boys with
Heterozygous Familial Hypercholesterolemia
In a double-blind, placebo-controlled study, 132 boys
10-17 years of age (mean age 12.7 yrs) with heterozygous familial
hypercholesterolemia (heFH) were randomized to lovastatin (n=67) or placebo (n=65)
for 48 weeks. Inclusion in the study required a baseline LDL-C level between
189 and 500 mg/dL and at least one parent with an LDL-C level > 189 mg/dL.
The mean baseline LDL-C value was 253.1 mg/dL (range: 171-379 mg/dL) in the
MEVACOR group compared to 248.2 mg/dL (range: 158.5-413.5 mg/dL) in the placebo
group. The dosage of lovastatin (once daily in the evening) was 10 mg for the
first 8 weeks, 20 mg for the second 8 weeks, and 40 mg thereafter.
MEVACOR significantly decreased plasma levels of total-C,
LDL-C and apolipoprotein B (see Table V).
TABLE V : Lipid-lowering Effects of Lovastatin in
Adolescent Boys with Heterozygous Familial Hypercholesterolemia (Mean Percent
Change from Baseline at Week 48 in Intention-to-Treat Population)
DOSAGE |
N |
TOTAL-C |
LDL-C |
HDL-C |
TG* |
Apolipoprotein B |
Placebo |
61 |
-1.1 |
-1.4 |
-2.2 |
-1.4 |
-4.4 |
MEVACOR |
64 |
-19.3 |
-24.2 |
+ 1.1 |
-1.9 |
-21 |
*data presented as median percent changes |
The mean achieved LDL-C value was 190.9 mg/dL (range:
108-336 mg/dL) in the MEVACOR group compared to 244.8 mg/dL (range: 135-404
mg/dL) in the placebo group.
Efficacy of Lovastatin in Post-Menarchal Girls with
Heterozygous Familial Hypercholesterolemia
In a double-blind, placebo-controlled study, 54 girls
10-17 years of age who were at least 1 year post-menarche with heFH were
randomized to lovastatin (n=35) or placebo (n=19) for 24 weeks. Inclusion in
the study required a baseline LDL-C level of 160-400 mg/dL and a parental
history of familial hypercholesterolemia. The mean baseline LDL-C value was
218.3 mg/dL (range: 136.3-363.7 mg/dL) in the MEVACOR group compared to 198.8
mg/dL (range: 151.1-283.1 mg/dL) in the placebo group. The dosage of lovastatin
(once daily in the evening) was 20 mg for the first 4 weeks, and 40 mg
thereafter.
MEVACOR significantly decreased plasma levels of total-C,
LDL-C, and apolipoprotein B (see Table VI).
TABLE VI: Lipid-lowering Effects of Lovastatin in
Post-Menarchal Girls with Heterozygous Familial Hypercholesterolemia (Mean
Percent Change from Baseline at Week 24 in Intention-to-Treat Population)
DOSAGE |
N |
TOTAL-C |
LDL-C |
HDL-C |
TG.* |
Apolipoprotein B |
Placebo |
18 |
+3.6 |
+2.5 |
+4.8 |
-3.0 |
+6.4 |
MEVACOR |
35 |
-22.4 |
-29.2 |
+2.4 |
-22.7 |
-24.4 |
*data presented as median percent changes |
The mean achieved LDL-C value was 154.5 mg/dL (range:
82-286 mg/dL) in the MEVACOR group compared to 203.5 mg/dL (range: 135-304
mg/dL) in the placebo group.
The safety and efficacy of doses above 40 mg daily have
not been studied in children. The long-term efficacy of lovastatin therapy in
childhood to reduce morbidity and mortality in adulthood has not been established.
REFERENCES
1 Kantola, T, et al., Clin Pharmacol Ther
1998; 63(4):397-402.