CLINICAL PHARMACOLOGY
Cholesterol and triglycerides circulate as part of lipoprotein complexes throughout the bloodstream.
These complexes can be separated via ultracentrifugation into high-density
lipoprotein (HDL), intermediate-density lipoprotein (IDL), low-density lipoprotein
(LDL) and very-low-density lipoprotein (VLDL) fractions. In the liver, cholesterol
and triglycerides (TG) are synthesized, incorporated into VLDL, and released
into the plasma for delivery to peripheral tissues.
A variety of clinical studies have demonstrated that elevated levels of total
cholesterol (total-C), LDL-C, and apolipoprotein B (apo-B, a membrane complex
for LDL-C) promote human atherosclerosis. Similarly, decreased levels of HDL-C
(and its transport complex, apolipoprotein A) are associated with the development
of atherosclerosis. Epidemiologic investigations have established that cardiovascular
morbidity and mortality vary directly with the level of total-C and LDL-C and
inversely with the level of HDL-C.
Like LDL, cholesterol-enriched triglyceride-rich lipoproteins, including VLDL,
IDL and remnants, can also promote atherosclerosis. Elevated plasma triglycerides
are frequently found in a triad with low HDL-C levels and small LDL particles,
as well as in association with nonlipid metabolic risk factors for coronary
heart disease. As such, total plasma TG has not consistently been shown to be
an independent risk factor for CHD. Furthermore, the independent effect of raising
HDL or lowering TG on the risk of coronary and cardiovascular morbidity and
mortality has not been determined.
In patients with hypercholesterolemia, BAYCOL® (cerivastatin (removed from market 8/2001)) (cerivastatin sodium tablets)
has been shown to reduce plasma total cholesterol, LDL-C, and apolipoprotein
B. In addition, it also reduces VLDL-C and plasma triglycerides and increases
plasma HDL-C and apolipoprotein A-1. The agent has no consistent effect on plasma
Lp(a). The effect of BAYCOL® (cerivastatin (removed from market 8/2001)) on cardiovascular morbidity and mortality has
not been determined.
Mechanism of Action: Cerivastatin is a competitive inhibitor of HMG-CoA
reductase, which is responsible for the conversion of 3-hydroxy-3-methyl-glutaryl-coenzyme
A (HMG-CoA) to mevalonate, a precursor of sterols, including cholesterol. The
inhibition of cholesterol biosynthesis by cerivastatin reduces the level of
cholesterol in hepatic cells, which stimulates the synthesis of LDL receptors,
thereby increasing the uptake of cellular LDL particles. The end result of these
biochemical processes is a reduction of the plasma cholesterol concentration.
Pharmacokinetics
Absorption: BAYCOL® (cerivastatin sodium tablets) is administered
orally in the active form. The mean absolute bioavailability of cerivastatin
following a 0.2-mg tablet oral dose is 60% (range 39 - 101%). In general, the
coefficient of variation (based on the inter-subject variability) for both systemic
exposure (area under the curve, AUC) and Cmax is in the 20% to 40% range. The
bioavailability of cerivastatin sodium tablets is equivalent to that of a solution
of cerivastatin sodium. No unchanged cerivastatin is excreted in feces. Cerivastatin
exhibits linear kinetics over the dose range of 0.2 to 0.8-mg daily. In male
and female patients at steady-state, the mean maximum concentrations (Cmax)
following evening cerivastatin tablet doses of 0.2, 0.3, 0.4, and 0.8-mg are
2.8, 5.1, 6.2, and 12.7 µg/L, respectively. AUC values are also dose–proportional
over this dose range and the mean time to maximum concentration (tmax) is approximately
2 hours for all dose strengths. Following oral administration, the terminal
elimination half-life (t1/2) for cerivastatin is 2 to 4 hours. Steady-state
plasma concentrations show no evidence of cerivastatin accumulation following
administration of up to 0.8 mg daily.
Results from an overnight pharmacokinetic evaluation following single-dose
administration of cerivastatin with the evening meal or 4 hours after the evening
meal showed that administration of cerivastatin with the evening meal did not
significantly alter either AUC or Cmax compared to dosing the drug 4 hours after
the evening meal. In patients given 0.2 mg cerivastatin sodium once daily for
4 weeks, either at mealtime or at bedtime, there were no differences in the
lipid-lowering effects of cerivastatin. Both regimens of 0.2 mg once daily were
slightly more efficacious than 0.1 mg twice daily.
Distribution: The volume of distribution (VDss) is calculated
to be 0.3 L/kg. More than 99% of the circulating drug is bound to plasma proteins
(80% to albumin). Binding is reversible and independent of drug concentration
up to 100 mg/L.
Metabolism: Biotransformation pathways for cerivastatin in humans
include the following: demethylation of the pyridilic methyl ether to form M1
and hydroxylation of the methyl group in the 6'-isopropyl moiety to form M23.
The combination of both reactions leads to formation of metabolite M24. The
major circulating blood components are cerivastatin and the pharmacologically
active M1 and M23 metabolites. The relative potencies of metabolites M1 and
M23 are comparable to, but do not exceed, the potency of the parent compound.
Following a 0.8-mg dose of cerivastatin to male and female patients, mean steady
state Cmax values for cerivastatin, M1, and M23 were 12.7, 0.55, and 1.4 µg/L,
respectively. Therefore, the cholesterol-lowering effect is due primarily to
the parent compound, cerivastatin.
In vitro studies show that the hepatic cytochrome P450 (CYP) enzyme
system catalyzes the cerivastatin biotransformation reactions. Specifically,
two P450 enzyme sub-classes are involved. The first is CYP 2C8, which leads
predominately to the major active metabolite, M23, and to a lesser extent, the
other active metabolite, M1. The second is CYP 3A4, which primarily contributes
to the formation of the less abundant metabolite, M1. The CYP 3A4 enzyme sub-class
is also involved in the metabolism of a significant number of common drugs.
The effect of the dual pathways of hepatic metabolism for cerivastatin is shown
in clinical studies examining the effect of the known potent CYP 3A4 inhibitors,
erythromycin and itraconazole. In these interaction studies, specific inhibition
of the CYP 3A4 enzyme sub-class resulted in a 1.4- to 1.5-fold mean increase
in cerivastatin plasma levels following co-treatment with erythromycin or itraconazole,
possibly because of metabolism via the alternate CYP 2C8 pathway.
Excretion: Cerivastatin itself is not found in either urine or
feces; M1 and M23 are the major metabolites excreted by these routes. Following
an oral dose of 0.4 mg 14C-cerivastatin to healthy volunteers, excretion
of radioactivity is about 24% in the urine and 70% in the feces. The parent
compound, cerivastatin, accounts for less than 2% of the total radioactivity
excreted. The plasma clearance for cerivastatin in humans after intravenous
dosing is 12 to 13 liters per hour.
Special Populations
Geriatric: Plasma concentrations of cerivastatin are similar
in healthy elderly male subjects ( > 65 years) and in young males ( <
40 years).
Gender: Plasma concentrations of cerivastatin in females are
slightly higher than in males (approximately 12% higher for Cmax and 16% higher
for AUC).
Pediatric: Cerivastatin pharmacokinetics have not been studied
in pediatric patients.
Race: Cerivastatin pharmacokinetics were compared across studies
in Caucasian, Japanese and Black subjects. No significant differences in AUC,
Cmax, tmax, and t1/2 were found.
Renal: Steady-state plasma concentrations of cerivastatin are
similar in healthy volunteers (Clcr > 90 mL/min/1.73m2)
and in patients with mild renal impairment (Clcr 61-90 mL/min/1.73m2).
In patients with moderate (Clcr 31-60 mL/min/1.73m2) or
severe (Clcr ≤ 30 mL/min/1.73m2) renal impairment, AUC is up to
60% higher, Cmax up to 23% higher, and t1/2 up to 47% longer compared
to subjects with normal renal function.
Hemodialysis: While studies have not been conducted in patients
with end-stage renal disease, hemodialysis is not expected to significantly
enhance clearance of cerivastatin since the drug is extensively bound to plasma
proteins.
Hepatic: Cerivastatin has not been studied in patients with active
liver disease (see CONTRAINDICATIONS). Caution
should be exercised when BAYCOL® (cerivastatin sodium tablets) is administered
to patients with a history of liver disease or heavy alcohol ingestion (see
WARNINGS).
Clinical Studies
BAYCOL® (cerivastatin sodium tablets) has been studied in controlled trials
in North America, Europe, Israel, and South Africa and has been shown to be
effective in reducing plasma Total-C, LDL-C, VLDL-C, apo B, and TG and increasing
HDL-C and apo A1 in patients with heterozygous familial and non-familial forms
of hypercholesterolemia and in mixed dyslipidemia. Over 5,000 patients with
Type IIa and IIb hypercholesterolemia were treated in trials of 4 to 104 weeks
duration.
The effectiveness of BAYCOL® (cerivastatin (removed from market 8/2001)) in lowering plasma cholesterol has been shown
in men and women, in patients with and without elevated triglycerides, and in
the elderly. In four large, multicenter, placebo-controlled dose response studies
in patients with primary hypercholesterolemia, BAYCOL® (cerivastatin (removed from market 8/2001)) given as a single
daily dose over 8 weeks, significantly reduced Total-C, LDL-C, apo B, TG, total
cholesterol/HDL cholesterol (Total-C/HDL-C) ratio and LDL cholesterol/HDL cholesterol
(LDL-C/HDL-C) ratio. Significant increases in HDL-C were also observed. The
median (25th and 75th percentile) percent changes from baseline in HDL-C for
Baycol (cerivastatin (removed from market 8/2001)) 0.2, 0.3, 0.4, and 0.8 mg were +8 (+1, +15), +8 (+1, +14), +7 (0, +14),
and +9 (+2, +16), respectively. Significant reductions in mean total-C and LDL-C
were evident after one week, peaked at four weeks, and were maintained for the
duration of the trial. (Pooled results at week 8 are presented in Table 1).
Table 1: Response in Patients with Primary Hypercholesterolemia
Mean Percent Change from Baseline to Week 8 Intent-To-Treat Population
Dosage |
N1 |
Total-C |
LDL-C |
Apo-B |
TG2 |
HDL-C |
LDL-C/HDL-C |
Total-C/HDL-C |
Placebo |
608-620 |
+1 |
0 |
+1 |
0 |
+2 |
-1 |
0 |
BAYCOL® qd |
0.2 mg |
150-151 |
-18 |
-25 |
-19 |
-16 |
+9 |
-31 |
-24 |
0.3 mg |
494-497 |
-22 |
-31 |
-24 |
-16 |
+8 |
-35 |
-27 |
0.4 mg |
754-758 |
-24 |
-34 |
-27 |
-16 |
+7 |
-38 |
-29 |
0.8 mg |
731-735 |
-30 |
-42 |
-33 |
-22 |
+9 |
-46 |
-35 |
1 - N given as a range since test results for each lipid
variable were not available in every patient
2 - Median percent change from baseline |
In a pool of eight studies in patients with hypercholesterolemia and TG levels
ranging from 250 mg/dL to 500 mg/dL who were treated for at least eight weeks,
the following reductions in TG and increases in HDL-C were observed at Week
8 as shown in Table 2 below:
Table 2: Median Percent Change from Baseline to Week 8 in
Patients with Baseline TG between 250-500 mg/dL
|
Placebo |
BAYCOL® 0.2 mg |
BAYCOL® 0.3 mg |
BAYCOL® 0.4 mg |
BAYCOL® 0.8 mg |
N1 |
135-138 |
127-129 |
156-157 |
139 |
125 |
Triglycerides |
-3.3 |
-22.6 |
-22.4 |
-26.2 |
-30.7 |
HDL-C |
3.1 |
7.3 |
9.2 |
10.7 |
13.3 |
1 - N given as a range since test results for each lipid variable
were not available in every patient |
In a large clinical study, the number of patients meeting their National Cholesterol Education Program-Adult Treatment Panel (NCEP-ATP) II target LDL-C levels on BAYCOL® (cerivastatin (removed from market 8/2001)) 0.4 and 0.8 mg daily was assessed. The results up to 24 weeks are shown in Table 3 below:
Table 3: Percent of Patients Reaching NCEP-ATP II Goal Up
to 24 Weeks of Treatment with BAYCOL® (cerivastatin (removed from market 8/2001)) 0.4 mg and 0.8 mg
NCEP-ATP II Treatment Guidelines |
Patients Reaching LDL-C Target Up to 24 Weeks |
Risk Factors for CHD |
Baseline LDL-C (mg/dL) |
Target LDL-C (mg/dL) |
BAYCOL® 0.4 mg |
BAYCOL® 0.8 mg |
|
|
|
Baseline LDL-C Mean (mg/dL) |
Percent To Goal |
Baseline LDL-C Mean (mg/dL) |
Percent To Goal |
< 2 risk factors |
≥ 190 |
< 160 |
234 (n=33) |
79% |
224 (n=156) |
79% |
≥ 2 risk factors |
≥ 160 |
< 130 |
204 (n=43) |
65% |
201 (n=186) |
72% |
CHD |
≥ 130 |
≤ 100 |
188 (n=34) |
24% |
187 (n=99) |
53% |