Inhibace Plus - Pharmaceutical Information, Clinical Trials, Detailed Pharmacology, Toxicology
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Inhibace Plus - Scientific Information

Manufacture: Roche
Country: Canada
Condition: Hypertension (High Blood Pressure)
Class: Angiotensin converting enzyme inhibitors
Form: Tablets
Ingredients: Cilazapril, Hydrochlorothiazide, Cornstarch, Hydroxypropyl methycellulose, Lactose, Red iron oxide, Sodium stearyl fumarate, Talc, Titanium dioxide

Pharmaceutical Information

Drug Substance: Cilazapril Monohydrate Hydrochlorothiazide
Proper Names: cilazapril monohydrate hydrochlorothiazide
Chemical Names: 9 (s)-[1(s)-(ethoxycarbonyl)-3- phenylpropylamino]- octahydro-10-oxo-6H- pyridazo [1,2-a] [1,2] diazepine-1(s)-carboxylic acid monohydrate 6-chloro-3,4-dihydro-2H-1,2,4- benzothiadiazine-7-sulfonamide 1,1dioxide
Molecular Formulas: C22H31N3O5°H2O C7H8ClN3O4S2
Structural Formulas



Molecular Weights: 435.52 297.72
Physical Forms: Cilazapril is a white to offwhite crystalline powder Hydrochlorothiazide is a white or practically white crystalline compound.
Solubility: Water (25°C) 0.5 g/100 mL Practically insoluble in water
pka1, pka2: 3.3, 6.4 7.9, 9.2
pH (1%) suspension): 4.9
Partition Co-efficient: 0.8 (octanol-pH 7.4 buffer 22°C)
Melting Point: 98°C with decomposition 131°C with decomposition

Detailed Pharmacology

Cilazapril Pharmacology

In in vitro studies, using hippurylhistidylleucine as substrate, cilazaprilat, the active metabolite of cilazapril, inhibited the activity of ACE from rabbit lung (IC50 0.97-1.93 nM), hog lung (IC50 2.83 nM), human lung (IC50 1.39 nM), and human plasma (IC50 0.61 nM). Cilazaprilat (20 μM) did not have any effect on a number of other porcine, bovine, or human enzymes except E. coli dipeptidyl carboxypeptidase.

In ex vivo studies, oral administration of 0.1 and 0.25 mg/kg cilazapril to rats inhibited plasma ACE activity by 76% and 96% respectively and 0.3-3 mg/kg significantly inhibited tissue ACE activity in a number of arteries and veins.

In vivo, the dose of cilazapril and/or cilazaprilat required to reduce the angiotensin pressor response by 50% are summarized in Table 1 below.

Table 1
ED50 Values for Cilazapril and/or Cilazaprilat
Animal Model Cilazapril Activity Cilazaprilat Activity
Conscious normotensive rats ED50 0.02 mg/kg p.o. (at 60 min)
Anesthetised SHAD (unilaterally adrenalectomised and contralaterally adrenal demedulated SHR) rats ED50 0.44 μmol/kg i.v. ED50 0.06 μmol/kg i.v.
2-kidney-1-clip Goldblatt renal hypertensive rats ED50 0.043 mg/kg i.v. ED50 0.006 mg/kg i.v.
Anesthetised normotensive dogs ED50 0.035 mg/kg i.v. (0.084 μmol/kg)

In the anesthetised SHAD rats 0.06 μmol/kg i.v. cilazaprilat potentiated the bradykinin induced vasodepressor response.

The antihypertensive activity of cilazapril was assessed in a number of experimental animal models. In spontaneously hypertensive rats (SHR), single oral doses of 10 and 30 mg/kg cilazapril reduced systolic blood pressure for longer than six hours. Repeated daily dosing with oral doses of 10 and 30 mg/kg cilazapril demonstrated 24-hour activity and at the higher dose, antihypertensive effect became maximum after one week. When administered twice daily, the lowest oral dose of cilazapril that reduced systolic blood pressure was 1 mg/kg. Dose dependent decreases in systolic blood pressure were observed between oral doses of 1 and 10 mg/kg twice daily. No further increase in effect was observed with an oral dose of 30 mg/kg twice daily.

Intravenous administration of up to 10 mg/kg of either cilazapril or cilazaprilat to conscious SHR evoked only small reductions in blood pressure. The reason for this disparity with the oral dosing data in the same animal model is unclear.

Following the oral administration of 10 mg/kg cilazapril, the maximum decrease in systolic arterial pressure observed in conscious renal hypertensive hypovolemic dogs was approximately double that observed in normovolemic dogs. In the hypovolemic dogs, the systolic blood pressure fell significantly within 30 minutes of the first dose. The effect persisted for 6 hours. Maximum decrease in systolic arterial pressure in conscious normotensive hypovolemic dogs was similar to that observed in renal hypotensive normovolemic dogs.

Heart rate changes accompanying the antihypertensive action of cilazapril in the rat and the dog were minimal.

Total peripheral resistance and regional vascular resistance were reduced in all vascular beds except in the heart in SHR administered multiple, oral, daily doses of 10 mg/kg cilazapril. Regional blood flow to the kidneys, intestine and skin increased. Regional blood flow to the heart decreased. No changes were observed in cardiac output, cardiac index, stroke volume or heart rate. Hemodynamic and blood flow changes were similar after acute or repeated (twice daily for two weeks) administration of 1 mg/kg cilazapril. Additional increases in blood flow to the lungs, stomach, small intestine, pancreas and thymus were observed, however.

In conscious dogs, cilazapril had no effect on left ventricular pressure and on force of cardiac contraction at 3 mg/kg p.o. and marginal effects at 10 mg/kg p.o. At these doses, slight decreases were noted in abdominal aortic blood flow and heart rate. In anesthetized dogs, intravenous cilazapril doses of 0.03-1 mg/kg evoked dose dependent decreases in blood pressure and left ventricular pressure. At 1 mg/kg, left ventricular end diastolic pressure was decreased 15%, myocardial contractile force was reduced and heart rate was unchanged. At 0.3 mg/kg, cardiac output, coronary blood flow, left ventricular minute work, left ventricular stroke work, and cardiac index were decreased 15%, 12%, 31%, 40%, and 12% respectively. In the anesthetized dog with ischemic heart failure, intravenous doses of cilazaprilat (0.1-1 mg/kg) reduced total peripheral resistance, left ventricular end diastolic pressure, dp/dt, and mean aortic blood pressure. Cardiac output, heart rate, pulmonary arterial pressure and right arterial pressure remained unchanged.

Oral administration of 3 mg/kg cilazapril did not have an effect on the increase in blood pressure and heart rate accompanying exercise in conscious cats. In anesthetized cats, cilazapril (10 mg/kg i.v.) increased right ventricular force of contraction (28%) and cardiac output (19%). Heart rate changes were minor.

The pharmacokinetics of cilazapril and cilazaprilat have been examined in mice, rats, dogs, monkeys, marmosets and baboons. The oral absorption of cilazapril is rapid and peak plasma concentrations of cilazapril occur in less than 1 hour. Absorption is 70-89%. Cilazapril plasma concentrations decline rapidly with a half-life of 0.7-2.7 hours. Plasma concentrations are less than dose proportional in baboons, and in rats and marmoset levels are too low for reliable quantitation.

Cilazaprilat is produced rapidly in all species and peak concentrations occur in less than 1.5 hours. Bioavailability from oral cilazapril is 70-89%. Cilazaprilat plasma concentrations decline in a biphasic manner with half lives of 0.5-3.5 hours and 12-68 hours. Plasma concentrations are less than dose proportional, and show a low order of dose dependence during the terminal phase. This is consistent with saturable binding to ACE.

The distribution of drug related material is largely confined to excretory organs, but all major tissues are exposed, including the fetus of pregnant animals. There is no evidence of tissue retention, and more than 95% of the dose is recovered within three days. Repeat administration leads to some accumulation, but only in a limited number of tissues, notably the liver and kidney. Excretion is rapid in all species. More than 90% of the total recovery in urine is achieved within 24 hours. Excretion is predominantly hepatic in rats and baboons, and renal in marmosets.

Hydrochlorothiazide Pharmacology

Hydrochlorothiazide increases the renal excretion of sodium and chloride in approximately equivalent amounts with an accompanying volume of water and causes a simultaneous, usually minimal loss of bicarbonate. The excretion of ammonia is reduced slightly by hydrochlorothiazide and the blood ammonia concentration may be increased. The excretion of potassium is increased slightly. Calcium excretion is decreased by hydrochlorothiazide and magnesium excretion is increased.

Hydrochlorothiazide is eliminated rapidly by the kidney. Its rate of elimination is decreased somewhat by the co-administration of probenecid without, however, an accompanying reduction in diuresis.

For a complete discussion of the pharmacology of hydrochlorothiazide, please consult the Product Monographs for hydrochlorothiazide products.

Cilazapril/Hydrochlorothiazide Pharmacology

In view of the extensive preclinical and clinical experience available with cilazapril and hydrochlorothiazide individually, and also with hydrochlorothiazide in combination with other ACE inhibitors, only limited studies were undertaken to specifically examine the preclinical pharmacology of the combination.

Table 2
Pre-clinical Pharmacology Studies: Cilazapril/Hydrochlorothiazide
Study Species Route of Administration Dose (Mg/Kg) Results/ Observations
Effects of HCTZ on cilazapril.
Modulation by HCTZ of anti-hypertensive actions of cilazapril in spontaneously hypertensive rats.
Male SHR
Unilaterally adrenaldemedullated and contralaterally adrenalectomized
p.o. 10 (cilazapril) 30 (HCTZ) Although HCTZ alone had no effect on blood pressure, it significantly increased (by up to 24 mm Hg) the reduction in blood pressure induced by cilazapril.

Toxicology

Table 3
Pharmacokinetic/ Toxicokinetics of Cilazapril / Hydrochlorothiazide
Study Species Description N Dose/Route/Form Conclusion
1 Rat 6-month oral toxicity 10 x 6M, 6F 0 (vehicle), 0.45 (0.2/0.25), 4.95 (2.2/2.75), 56.0 (24.9/31.1), 2.7 (0.2/2.5), 29.7 (2.2/27.5), 337.5 (25.0/312.5) cilazapril/ hydrochlorothiazide; 25.0 cilazapril alone; 31.0 and 312.5 hydrochlorothiazide alone/oral/suspension No drug accumulation of CLZ1 or HCTZ2 after repetitive dosing of each alone. When CLZ/HCTZ was dosed, increasing HCTZ accumulation was observed with increasing HCTZ dose. HCTZ did not affect the disposition of CLZ when these drugs were coadministered.
2 Baboon 13-week toxicity 7 x 2M, 2F 0, 6.75 (0.5/6.25), 40.5 (3.0/37.5), 270 (20/250), 6.25 (0/6.25), 37.5 (0/37.5), 250 (0/250)/oral/ suspension Administration of CLZ/HCTZ in a 1:125 ratio at 40.5 or 270 mg/kg/d resulted in decreased plasma clearance of HCTZ and slight decrease of CLZT3 plasma clearance by Day 7.
3 Baboon 26-week toxicity 4 x 2M, 2F 0, 1.125 (0.5/0.625), 6.75 (3.0/3.75), 45 (20/25)/oral/suspension The disposition of CLZT and HCTZ remained largely unchanged during the 26 weeks of dosing.

Cilazapril

Hydrochlorothiazide

Cilazaprilat

Table 4
Cilazapril Acute Toxicity
Species Sex Route Approximate LD50 (mg/kg)
Mouse M
F
M + F
M
F
M + F
p.o.
p.o.
i.v.
i.p.
i.p.
s.c.
4,600
2,500 - <5,000
>250
1,600
1,300
>1,000
Rat M + F
M + F
p.o.
i.p.
>4,000 - <5,000
830
Monkey M + F p.o. >4,000 - <5,000

The signs of toxicity include: ataxia, reduced motor activity, diarrhea, respiratory depression, tremors, piloerection, prostration, hunched appearance, salivation, emesis and facial fur-staining.

Table 5
Cilazapril / Hydrochlorothiazide Acute Toxicity
Species Sex Route Observations/ LD50 (mg/kg)
Mouse M p.o.1 CLZ4 + HCTZ5 (6:10) - 3,500 expressed as CLZ component.
CLZ - 3,300
HCTZ - >8,300
Mouse
Rat
M+F p.o.2
p.o.3
No mortalities or clinical observations were noted.

1 Gavage

2 Capsule - 50 capsules/kg (mouse)

3 Capsule - 30 capsules/kg (rat)

4 Cilazapril

5 Hydrochlorothiazidea

Table 6
Long-Term Toxicity of Cilazapril
Species (#/group) Study duration Dose administration (mg/kg/day) Route Findings
Rat (8M + 8F) 2 Weeks 0, 2, 6, 20 i.v. All dose groups: Swollen tails in individual rats after 8-10 days; slight increase in urine volume (males).
Monkey Marmoset (3M + 3F) 2 Weeks 0, 2, 6, 20 i.v. All dose groups: Slightly depressed heart rates.
Rat (5M + 5F) 4 Weeks 0, 5, 15, 50 p.o. All dose groups: Increased water consumption.

15 and 50 mg/kg/day: Minimal decreases in RBC, Hb and PCV values (females); increase in plasma urea (2-3x).

50 mg/kg/day: Salivation (6/10) from week 2; decrease body weight gain (20%); slight reduction in food consumption; increased incidence of kidney tubule cells in urine (females).
Rat (16M + 16F) 4 Weeks 25, 125, 625 p.o. All dose groups: Salivation; slight reduction in motor activity; increased urine volumes and minimal decreases in specific gravity (males).

125 and 625 mg/kg/day: Decreased body weight gain and food consumption (males only at 125 mg/kg/day); slight decreases in RBC, Hb and PCV (males); very slight thickening of glomerular afferent arteriolar wall in the kidney (males) (1/10 125 mg/kg/day, 6/10 - 625 mg/kg/day).

625 mg/kg/day: Increased BUN values (1.5x) (males); decreased BMC1 (males); slight decrease in heart and liver (males) weight.
Monkey Marmoset (3/6M + 3F) 4 Weeks 0, 5, 15, 50 p.o. 15 and 50 mg/kg/day: Marginal decreases in RBC, Hb and PCV values.

50 mg/kg/day: Increase in plasma urea (2x), K+ and cholesterol values; increased incidence of kidney tubule cells in urine.
Rat (16M + 16F) 13 Weeks 0, 10, 50, 250 p.o. All dose groups: Very slight increases in urine volume and decreased SG values (males).

50 and 250 mg/kg/day: Dose-related decrease in body weight gain (males only at 50 mg/kg/day); increased BUN levels (2x) (males); slight thickening of glomerular afferent arterioles in the kidneys (10/30).

250 mg/kg/day: Slight decrease in spontaneous activity and salivation; inhibition of food consumption; small decreases in RBC and BMC (males), and in RBC, PCV and Hb (females).
Monkey Cynomolgus (4M + 4F) 13 Weeks 0, 2.5, 25, 50 p.o. 25 and 50 mg/kg/day: Slight decreases in RBC, Hb and PCV. Slight to moderate hyperplasia of the juxtaglomerular apparatus; dose-related decreased body weight gains.

50 mg/kg/day: Two deaths; salivation; emesis; decreased spontaneous activity. Slight decrease in BMC, total protein and inorganic phosphate; increase in BUN (4x), blood creatinine; enlargement of kidney (1 female); reduction in heart weight; kidney tubular dilatation.
Monkey Baboon (2M + 2F) 13 Weeks 0, 2, 10, 20, 40 p.o. All dose groups: Emesis; slight reductions in heart rate, body weight gain and heart weight; hypertrophy and hyperplasia of the juxtaglomerular cells (¼ - 10 mg/kg, ¾ - 20 mg/kg, 4/4 - 40 mg/kg).

20 and 40 mg/kg/day: Slight decrease in RBC, PCV and Hb; kidney tubular basophilia/ dilatation (¼ - 20 mg/kg; ¾ - 40 mg/kg). Increased urea (2x) in 40 mg/kg only.
Rat (30M + 30F) 26 Weeks 0, 5, 30, 200;
0, 2, 12, 75 - from Week 6; 0, 2, 12, 50 from Week 14
p.o. All dose groups: Slight decrease in heart rate; weight loss; lethargy; hunched posture. Piloerection; facial fur-staining; dose-related increases in kidney weights (male).

12 and 50 mg/kg/day: Hypertrophy of afferent glomerular arterioles in the kidneys (13 weeks).

50 mg/kg/day: Body weight gain decrease (14%) (males); increased water intake. Increased BUN levels (3x) (males), ALP activity, and liver weights (males); prominent kidney tubular regeneration; kidney tubular dilatation; minimal kidney tubular necrosis (2 animals at 13 weeks). Sclerosis (2 animals at 26 weeks).
Monkey Marmoset (9, 7, 7, 11M+ 9, 7, 7, 11F) 26 Weeks 0, 5, 30, 200;
0, 2, 15, 100 from Week 9; 0, 2, 15, 50 from Week 14
p.o. 200 mg/kg/day: Depression in heart rate; body weight loss (females).

15 mg/kg/day: Two deaths (unrelated to treatment) of minor glomerular arteriolar hypertrophy (13 and 26 weeks).

50 mg/kg/day: Six deaths (two unrelated to treatment); unsteadiness; inactivity; salivation; emesis; diarrhea; slight decrease in RBC, PCV, Hb and bone marrow, myeloid/erythroid ratio (26 weeks). Increase in plasma urea (2x); small reductions in urine osmolality; slight kidney tubular dilatation and tubular epithelium regeneration (4/5 at 13 weeks - 100 mg/kg) (4/10 after 26 weeks).
Monkey Baboon (7M + 7F) 52 Weeks 0, 0.5, 4, 40 p.o. 4 and 40 mg/kg/day: Hyperplasia and hypertrophy of juxtaglomerular apparatus with hypertrophy of muscle cells of glomerular arterioles (1/10 - 4 mg/kg; 8/10 - 40 mg/kg/day).

40 mg/kg/day: Emesis; body weight gain reduction; slight reduction in RBC, PCV and Hb; increase in urea values (2x) and creatinine; osmolality reductions; increased incidence in proteinous casts (Week 52); small increase in adrenal and thyroid weights.
Rat (35M + 35F) 78 Weeks 0, 0.5, 4, 40 p.o. All dose levels: Small reductions in body weight gain.

4 and 40 mg/kg/day: Slight decrease in RBC, PCV and Hb; minimal reduction in food intake; increase in BUN (2x) (males).

40 mg/kg/day: Increased water consumption; slight increase in total WBC count (males); increased urine volumes (males); irregular surface ocysts in the kidneys (7/40 at 76 weeks); increased kidney weights (males); slight decrease in heart and liver weight (females); vascular hypertrophy (20/20 males, 17/20 females) consisting of glomerular afferent arteriolar wall thickening; similar but less frequent and less severe changes were observed in the mid-dose group.

Hydrochlorothiazide Toxicology

For a complete discussion of the Toxicology of hydrocholorothiazide, please consult the Product Monograph for HYDRODIURIL (Merck Sharp & Dohme Canada).

Hydrochlorothiazide was found to have relatively low toxicity in acute and chronic toxicity studies. In acute animal toxicity studies in mice the LD50 was greater than 10,000 mg/kg suspension orally and was 884 mg/kg intravenously. In rats the acute LD50 was greater than 10,000 mg/kg suspension orally and 3,130 mg/kg suspension intraperitoneally. In the rabbit the acute intravenous LD50 was 461 mg/kg and in the dog it was approximately 1,000 mg/kg. Dogs tolerated at least 2,000 mg/kg orally without signs of toxicity.

Subacute oral toxicity studies in the rat at 500, 1,000 and 2,000 mg/kg/day of suspension five days a week for three weeks displayed no sign of drug effect. Three of the rats given

2000 mg/kg/day hydrochlorothiazide sodium salt died after the fifth day. These deaths were attributed to pneumonia. No sign of drug effect was observed among the other animals. In dogs given doses of 250, 500 and 1,000 mg/kg seven days a week for 8 weeks, no gross signs of drug effect were noted except for electrolyte imbalance.

Chronic oral toxicity studies in the rat using doses of up to 2,000 mg/kg/day 5 days per week for 26 weeks showed no signs of drug effect and no drug related changes on post mortem examination. In dogs oral doses of 0, 125, 250 mg/kg/day 5 days per week for 26 weeks;

500 mg/kg/day for 7 weeks; 11 weeks without drug then 500 mg/kg/day 7 days per week for 8 weeks, were given. Slight depression of plasma potassium, small amounts of yellow crystalline precipitate in the bladder in two of twelve dogs were found on gross examination.

Histomorphologic studies did not show drug related changes.

Hydrochlorothiazide has been administered to rats in a two-litter study, to mice in a two-generation study, and to rabbits in a established pregnancy test. None of these studies showed any evidence of teratogenic effects of hydrochlorothiazide. Offspring carried on to weaning or maturity did not show evidence of effects related to treatment.

Table 7
Long-Term Toxicity (Cilazapril / Hydrochlorothiazide)
Species (No./Group) Study Duration Doses (mg/kg/day)/Route of Administration Effects
Rat (6M1 + 6F2) 2 Weeks 0 (vehicle control), intubationa)
a) CLZ3 + HCTZ4 (1:5): 0.2 + 1; 2.5 + 12.5; 50 + 250
a) CLZ + HCTZ (1.5):
2.5 + 12.5- slight decrease serum sodium and serum chloride in males; relative kidney weight increase in females.
50 + 250 - decrease in body weight gain, food consumption, serum sodium and serum chloride;
– increase in serum BUN and relative kidney weights.
– slight increases in serum glucose in females.
– necrotic lesions in glandular mucosa of stomach.
b) CLZ + HCTZ (1:12.5):
0.2 + 2.5; 2.5 + 31.3; 50 + 625
b) CLZ + HCTZ (1:12.5):
2.5 + 31.3 - slight decrease serum sodium, serum potassium and serum chloride;
– decrease serum triglycerides in males and increased relative kidney weight in females.
50 + 625 - decrease in body weight gain, food consumption, serum calcium (males), serum sodium, serum chloride, serum potassium and serum triglycerides (males);
– increase in relative serum glucose (males) and serum BUN;
– increase in relative kidney weights (females), absolute and relative adrenal (male) and relative ovary weights;
– necrotic lesions in glandular mucosa of stomach.
c) HCTZ - 625 c) HCTZ - 625 - decrease in serum potassium (both sexes) and serum chloride (females).
Rat (12M + 12F) 26 Weeks
0 (vehicle control), intubation
a) CLZ + HCTZ (1:1.25):
0.2 + 0.25; 2.2 + 2.75; 25 + 31

a) CLZ + HCTZ (1:1.25):
2.2 +2.75 - slight decrease serum sodium and serum chloride (F); decrease absolute heart weight (M).
25 + 31 - slight decrease in urine specific gravity (M); increase serum BUN levels (41% in females, approximately doubled in males), decrease serum sodium and serum chloride, decrease serum calcium (M).
- relative kidney weight increase (M) and absolute heart weight decrease (M).
- hypertrophy and hyperplasia of the juxtaglomerular apparatus and hypertrophy of the renal afferent arterioles.

b) CLZ + HCTZ (1:12.5):
0.2 + 2.5; 2.2 + 27.5; 25 + 312.5

b) CLZ + HCTZ (1:12.5):
2.2 + 27.5 - decrease in body weight gain (M); increase in serum BUN (21% in females and 39% in males); slight decrease in serum sodium and serum chloride; relative kidney weight increase and absolute heart weight decrease (M).
25 + 312.5 - decrease in body weight gain and food consumption; slight decrease urine specific gravity (M); increase in serum BUN levels (60-100%); decrease serum sodium and serum chloride; decrease serum triglycerides and serum calcium (M); increase kidney weight and decrease absolute heart weight (M); relative thyroid weight increase (F); hypertrophy and hyperplasia of the juxtaglomerular apparatus and hypertrophy of the renal afferent arterioles.
c) CLZ - 25 c) CLZ - 25 - 38% increase in serum BUN (M) and decrease in serum sodium; hypertrophy and hyperplasia of the juxtaglomerular arterioles and hypertrophy of the renal afferent arterioles.
d) HCTZ - 31; 312.5
d) HCTZ - 31 - decrease in serum sodium (F), serum chloride and serum potassium.
312.5 - decrease in serum sodium (F), serum potassium and serum chloride, increase in absolute and relative kidney and thyroid weights (F).
Baboon 6M + 6F) 26 Weeks (8-Week recovery for 2/sex/group) 0 (vehicle control) CLZ + HCTZ (1:1.25):) 0.5 + 0.625; 3 + 3.75; 20 + 25 P.O. (gavage)
CLZ + HCTZ (1:1.25)
3 + 3.75
- reversible decrease in body weight gain (M), decrease in urine specific gravity.
- low grade hypertrophy of juxtaglomerular cells of kidneys.
20 + 25
- decrease in body weight gain and motor activity;
- reversible reduction in erythrocyte levels and reversible increase in serum BUN, serum creatinine and serum calcium;
- decrease in urine specific gravity and serum phosphorus;
- hypertrophy of renal afferent glomerular arterioles and juxtaglomerular cells.

1 Male

2 Female

3 Cilazapril

4 Hydrochlorothiazide

Cilazapril Carcinogenicity

An eighty-eight week carcinogenicity study with cilazapril was conducted in mice initially dosed at 5, 25 or 100 mg/kg/day, subsequently reduced to 1, 7 or 50 mg/kg/day from week 11 onwards. Another carcinogenicity study was conducted in rats in which dose levels of 0.5, 4 or 40 mg/kg/day were administered for 104 weeks. Hypertrophy of renal afferent glomerular arterioles and interlobular arteries, and increased cortical nephropathy were the only recorded findings and occurred in the mid- and high-dose groups in both studies.

Cilazapril Mutagenicity

No evidence of mutagenicity with cilazapril was found in the Ames test with or without metabolic activation (up to 2.0 mg/plate), Treatment and Plate test (up to 7,000 μcg/mL), unscheduled DNA synthesis assay (up to 200 μcg/mL), mutagenic assay with Chinese hamster V79 cells with or without metabolic activation (up to 4,800 μcg/mL), chromosomal aberration test with or without metabolic activation (up to 3,500 μcg/mL), or in vivo micronucleus test in mice (2.0 g/kg).

Cilazapril / Hydrochlorothiazide Mutagenicity

The Ames tests showed evidence of weak mutagenicity for cilazapril in combination with hydrocholorothiazide with and without metabolic activation. The activity was considered borderline but was reproducible and dose-dependent. This mutagenic effect correlated with the weak mutagenicity of the hydrochlorothiazide component of the combination.

The mutagenicity of the combination cilazapril and hydrochlorothiazide (at a ratio of 1:5) was assessed in the three additional mutagenicity tests. There was no evidence of gene mutation either in the presence or absence of exogenous metabolizing systems when the combination was tested in saccharomyces cerevisiae D7 yeast strain (up to 5,000 μcg/mL) and in Chinese hamster V79 cells (up to 1,920 μcg/mL). In addition, a mouse micronucleus tests (in vivo) carried out with a 1:5 combination of cilazapril and hydrochlorothiazide (up to 4.0 g/kg) showed no genotoxic activity in mouse bone marrow cells.

Table 8
Reproduction and Teratology (Cilazapril)
Species #/Group Dose (mg/kg/day) Route Duration Of Dosing Effects
Fertility and General Reproduction Performance
Rat Charles River (Crl:CD (SD) BR) (30M + 30F) 0, 1, 7, 50 p.o. Males — 70 days prior to mating and up to 14 days during mating. Females — 14 days before mating, during gestation and until Day 21 post-partum. All dose groups: No effect on mating or fertility at any dose. Retching reflex after dosing (dose-related) (males). Decreased body weight gain.
Males at 50 mg/kg/day: Six deaths (due to dosing error). Females at 50 mg/kg/day: Two deaths (50 mg/kg) (due to dosing error). Increased preimplantation loss (forced delivery group at 50 mg/kg).
F1 generation at 7 and 50 mg/kg/day: Reduced body weight at the end of lactation; increased incidence of dilatation of the renal pelvis. Reduction in viable fetuses due to a lower number of implantations (50 mg/kg).
Embryotoxicity
Charles River (CD) (35F) 0, 2, 30, 400 p.o. Days 6-17 of gestation. All dose groups: No effect on embryonic, fetal or postnatal development.
Females at 400 mg/kg/day: Body weight gain and food consumption were reduced during latter half of gestation. F1 generation at 400 mg/kg/day: Slight increase in renal cavitation incidence.
Fertility and General Reproduction Performance
Monkey Cynomolgus (10 or 11F) 0, 20 p.o. Days 21 to 31 or Days 32 to 45 of gestation. Control group: Reduced food consumption and diarrhea (5/10 females); 2/10 abortions between Days 51-53 of pregnancy; low incidence of skeletal variations in tail (2/8 fetuses) and ribs (2/8).
20 mg/kg/day — Days 21-31: Reduced food consumption (10/10 females); diarrhea (2/10); vomiting (2/10). Skeletal findings — ribs (2/8 fetuses), humeri (2/8), distal caudal variations (4/8), and prepuce not patent (2/8) — not treatment related.
20 mg/kg/day — Days 32-45: Decreased food consumption and/or diarrhea (11/11 females); 5/11 abortions; 2/11 maternal deaths (not treatment related). Caudal and humerus variations (1/5 fetuses) — not treatment related.
Peri- and Post-natal Toxicity
Rat Charles River (CDCrl:CD(SD) BR) (25 or 30F) 0, 1, 7, 50 p.o. Day 15 of gestation to Day 21 post-partum. Females at 50 mg/kg/day: 5 deaths on Day 18 postcoitus or Days 4-16 of lactation (due to dosing error).
F1 generation at 50 mg/kg/day: Increased pup mortality (4.9%); reduction in body weight gain during lactation; an associated slight delay in pinna unfolding.
Table 9
Reproduction and Teratology (Cilazapril / Hydrochlorothiazide)
Species (No./Sex/Dose) Treatment Days (Day Of Sacrifice) Doses (mg/kg/day)/ Route Of Administration Effects
Mouse (6F) Segment II Gestation days: 6-17 (18) 0 (vehicle control) CLZ + HCTZ (1:5): + 31; 25 + 125; 100 + 500; 400 + 2,000 P.O. (gavage) 100 + 500: - decrease in maternal body weight and slight increase post-implantation loss and resorption rate.
400 + 2,000: - decrease in maternal body weight and food consumption and an increase in salivation;
- decrease in fetal body weight and slight increase in post-implantation loss
Mouse (25F) Segment II Gestation days: 6-15 (18) 0 (vehicle control) CLZ + HCTZ (1:5): 6 + 30; 50 + 250; 400 + 2,000 P.O. (gavage) 50 + 250: - reduced ossification of frontal bones.
400 + 2,000: - slight decrease in maternal body weight gain starting day 6 of gestation; increase incidence of dilated renal pelvises, reduced ossification of frontal and parietal bones, misaligned sternebrae and sternebrae variants.
0 (vehicle control) CLZ + HCTZ (1:5): 6 + 31; 40 + 200; 90 + 450; 200 + 1,000 P.O. (gavage) 6 + 31: - muzzle staining.
40 + 200: - muzzle staining, salivation and decrease in maternal body weight gain and food consumption.
- decrease gravid uterine weights and fetal weights.
90 + 450: - muzzle staining, salivation and decrease in maternal body weight gain and food consumption.
- decrease gravid uterine weights and fetal weights.
- one dam found dead on gestation Day 20 exhibited tremors, hunched posture, weakness, uncoordinated and decreased movement and decreased respiration on gestation Day 19; a relationship to treatment cannot be excluded.
Rat (6F) Segment II Gestation days: 7-17 (20) 200 + 1,000: - muzzle staining, salivation, decrease in maternal body weight gain and food consumption.
- decrease gravid uterine weights and fetal weights.
- one dam was scarificed on gestation Day 19 after delivering three fetuses. This dam had red stained fur, decreased motor activity, decreased temperature, hunched position, labored respiration, weakness, thin condition and signs of dehydration; a relationship to treament cannot be excluded.
Rat (25F) Segment II Gestation days: 7-17 (20) 0 (vehicle control) CLZ + HCTZ (1:5): 6 + 31; 16 + 80; 40 + 200; P.O. (gavage) >6 + 31: - decrease maternal body weight gain and food consumption.
>16 + 80: - decrease in fetal weights
40 + 200: - increase in minor skeletal anomalies (retarded ossification in a variety of bones). Considered to be secondary to decreased fetal weights.