Absorption, Distribution and Excretion
Bioavailability of oral dosing is 3% to 4% in horses. In humans at least 37% of oral benazepril is absorbed and reaches peak plasma concentration in 0.5 hours to 1 hour. Other studies have shown a peak plasma concentration at a median of 1.5 hours.
Benazepril and benazeprilat are cleared predominantly by renal excretion in healthy subjects with normal renal function. Nonrenal (i.e., biliary) excretion accounts for approximately 11%-12% of benazeprilat excretion in healthy subjects.
The final population pharmacokinetic model in one study estimated the volume of distribution to be 203±69.9L.
The final population pharmacokinetic model of one study estimates the clearance to be 129±30.0L.
/MILK/ Minimal amounts of unchanged benazepril and of benazeprilat are excreted into the breast milk of lactating women treated with benazepril. A newborn child ingesting entirely breast milk would receive less than 0.1% of the mg/kg maternal dose of benazepril and benazeprilat.
Benazepril and benazeprilat are cleared predominantly by renal excretion. About 37% of an orally administered dose was recovered in urine as benazeprilat (20%), benazeprilat glucuronide (8%), benazepril glucuronide (4%) and as trace amounts of benazepril. Nonrenal (i.e., biliary) excretion accounts for approximately 11% - 12% of benazeprilat excretion. The effective half-life of benazeprilat following once daily repeat oral administration of benazepril hydrochloride is 10 to 11 hours. Thus, steady-state concentrations of benazeprilat should be reached after 2 or 3 doses of benazepril hydrochloride given once daily. Accumulation ratio based on AUC of benazeprilat was 1.19 following once daily administration.

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Metabolism / Metabolites
Cleavage of the ester group (primarily in the liver) converts benazepril to its active metabolite, benazeprilat. Benazepril and benazeprilat are conjugated to glucuronic acid prior to urinary excretion.
Benazepril and benazeprilat are cleared predominantly by renal excretion. About 37% of an orally administered dose was recovered in urine as benazeprilat (20%), benazeprilat glucuronide (8%), benazepril glucuronide (4%) and as trace amounts of benazepril. Nonrenal (i.e., biliary) excretion accounts for approximately 11% - 12% of benazeprilat excretion. The effective half-life of benazeprilat following once daily repeat oral administration of benazepril hydrochloride is 10 to 11 hours. Thus, steady-state concentrations of benazeprilat should be reached after 2 or 3 doses of benazepril hydrochloride given once daily. Accumulation ratio based on AUC of benazeprilat was 1.19 following once daily administration.
After oral dosing in healthy dogs, benazepril is rapidly absorbed and converted into the active metabolite benazeprilat with peak levels of benazeprilat occurring approximately 75 minutes after dosing.
Benazepril is almost completely metabolized to benazeprilat by cleavage of the ester group (primarily in liver). Both benazepril and benazeprilat undergo glucuronidation.

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Biological Half-Life
The half life of the prodrug benazepril is 2.7±8.5h. The half life of the active metabolite benazeprilat is 22.3±9.2h The accumulation half life of benazepril is 10 to 11 hours.
The elimination half life of benazeprilat is approximately 3.5 hours in healthy dogs. /Benazeprilat/
The effective half-life of benazeprilat following once daily repeat oral administration of benazepril hydrochloride is 10 to 11 hours. /Benazeprilat/

Toxicity Summary
IDENTIFICATION AND USE: Benazepril is the nonsulfydryl angiotensin converting enzyme (ACE) inhibitor. It is used for treating hypertension and the management of heart failure in human patients and in animals. HUMAN STUDIES: Sensitivity reactions, including anaphylactoid reactions and angioedema (including laryngeal angioedema and tongue edema) are potentially fatal. Head and neck angioedema involving the tongue, glottis, or larynx may cause airway obstruction. Rare ACE inhibitor-associated clinical syndrome manifested initially by cholestatic jaundice may progress to fulminant hepatic necrosis and is potentially fatal. Patients receiving an ACE inhibitor, including benazepril, who develop jaundice or marked elevations of hepatic enzymes should discontinue the drug and receive appropriate monitoring. Human overdoses of benazepril have not been reported, but the most common manifestation of human benazepril overdosage is likely to be hypotension, for which the usual treatment would be intravenous infusion of normal saline solution. Hypotension can be associated with electrolyte disturbances and renal failure. Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Resulting oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations. Potential neonatal adverse effects include skull hypoplasia, anuria, hypotension, renal failure, and death. ANIMAL STUDIES: Single oral doses of 3 g/kg benazepril were associated with significant lethality in mice. Rats, however, tolerated single oral doses of up to 6 g/kg. Reduced activity was seen at 1 g/kg in mice and at 5 g/kg in rats. In doses of 50-500 mg/kg/day benazepril had no adverse effect on the reproductive performance of male and female rats. No evidence of carcinogenicity was found when benazepril was administered to rats and mice for up to two years at doses of up to 150 mg/kg/day. No mutagenic activity was detected in the Ames test in bacteria (with or without metabolic activation), in an in vitro test for forward mutations in cultured mammalian cells, or in a nucleus anomaly test.

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Hepatotoxicity
Benazepril, like other ACE inhibitors, has been associated with a low rate of serum aminotransferase elevations (
Likelihood score: D (possible rare cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Because of the low levels of benazepril in breastmilk, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Benazepril is 96.7% protein bound while benazeprilat is 95.3% protein bound.

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Interactions
Because ACE inhibitors may promote kinin-mediated prostaglandin synthesis and/or release, concomitant administration of drugs that inhibit prostaglandin synthesis (e.g., aspirin, ibuprofen) may reduce the blood pressure response to ACE inhibitors, including enalapril. Limited data indicate that concomitant administration of ACE inhibitors with nonsteroidal anti-inflammatory agents (NSAIAs) occasionally may result in acute reduction of renal function; however, the possibility cannot be ruled out that one drug alone may cause such an effect. ... Aspirin and other NSAIAs also can attenuate the hemodynamic actions of ACE inhibitors in patients with congestive heart failure. Because ACE inhibitors share and enhance the effects of the compensatory hemodynamic mechanisms of heart failure, with aspirin and other NSAIAs interacting with the compensatory mechanisms rather than with a given ACE inhibitor per se, these desirable mechanisms are particularly susceptible to the interaction and a subsequent potential loss of clinical benefits. As a result, the more severe the heart failure and the more prominent the compensatory mechanisms, the more appreciable the interaction between NSAIAs and ACE inhibitors. Even if optimal dosage of an ACE inhibitor is used in the treatment of congestive heart failure, the potential cardiovascular and survival benefit may not be seen if the patient is receiving an NSAIA concomitantly. In several multicenter studies, concomitant admin of a NSAIA (i.e., a single 350-mg dose of aspirin) in patients with congestive heart failure inhibited favorable hemodynamic effects associated with ACE inhibitors, attenuating the favorable effects of these drugs on survival and cardiovascular morbidity. /ACE inhibitors/
Patients receiving coadministration of ACE inhibitor and mTOR inhibitor (e.g., temsirolimus, sirolimus, everolimus) therapy may be at increased risk for angioedema. Monitor for signs of angioedema. /ACE inhibitors/
Dual Blockade of the Renin-Angiotensin System (RAS) with angiotensin receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy. Most patients receiving the combination of two RAS inhibitors do not obtain any additional benefit compared to monotherapy. In general, avoid combined use of RAS inhibitors. Closely monitor blood pressure, renal function and electrolytes in patients on Lotensin and other agents that affect the RAS. Do not coadminister aliskiren with Lotensin in patients with diabetes. Avoid use of aliskiren with Lotensin in patients with renal impairment (GFR < 60 mL/min).
Hypoglycemia has been reported rarely in diabetic patients receiving angiotensin-converting enzyme (ACE) inhibitors, including benazepril, concomitantly with insulin or oral antidiabetic agents. Patients receiving these drugs concomitantly should be informed of the possibility of hypoglycemia and monitored appropriately.
For more Interactions (Complete) data for Benazepril (10 total), please visit the HSDB record page.

Arzneimittelforschung.1991 Jun;41(6):602-7;J Vet Med Sci.2007 Oct;69(10):1015-23.

Benazepril is a benzazepine that is benazeprilat in which the carboxy group of the 2-amino-4-phenylbutanoic acid moiety has been converted to the corresponding ethyl ester. It is used (generally as its hydrochloride salt) as a prodrug for the angiotensin-converting enzyme inhibitor benazeprilat in the treatment of hypertension and heart failure. It has a role as an EC 3.4.15.1 (peptidyl-dipeptidase A) inhibitor and a prodrug. It is a benzazepine, a dicarboxylic acid monoester, an ethyl ester and a lactam. It is functionally related to a benazeprilat. It is a conjugate base of a benazepril(1+).
Benazepril, brand name Lotensin, is a medication used to treat high blood pressure (hypertension), congestive heart failure, and chronic renal failure. Upon cleavage of its ester group by the liver, benazepril is converted into its active form benazeprilat, a non-sulfhydryl angiotensin-converting enzyme (ACE) inhibitor.
Benazepril is an Angiotensin Converting Enzyme Inhibitor. The mechanism of action of benazepril is as an Angiotensin-converting Enzyme Inhibitor. The physiologic effect of benazepril is by means of Decreased Blood Pressure.
Benazepril is an angiotensin-converting enzyme (ACE) inhibitor widely used in the therapy of hypertension. Benazepril is associated with a low rate of transient serum aminotransferase elevations and has been linked to rare instances of acute liver injury.
Benazepril is a carboxyl-containing angiotensin-converting enzyme (ACE) inhibitor with antihypertensive activity. As a prodrug, benazepril is metabolized to its active form benazeprilat. Benazeprilat competitively binds to and inhibits ACE, thereby blocking the conversion of angiotensin I to angiotensin II. This prevents the potent vasoconstrictive actions of angiotensin II resulting in vasodilation. Benazeprilat also decreases angiotensin II-induced aldosterone secretion by the adrenal cortex, which leads to an increase in sodium excretion and subsequently increases water outflow.
See also: Benazepril Hydrochloride (has salt form); D&C Yellow No. 10 (active moiety of); Amlodipine besylate; benazepril hydrochloride (annotation moved to).

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Drug Indication
Benazepril is indicated for the treatment of hypertension. It may be used alone or in combination with thiazide diuretics.
FDA Label

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Mechanism of Action
Benazeprilat, the active metabolite of Benazepril, competes with angiotensin I for binding at the angiotensin-converting enzyme, blocking the conversion of angiotensin I to angiotensin II. Inhibition of ACE results in decreased plasma angiotensin II. As angiotensin II is a vasoconstrictor and a negative-feedback mediator for renin activity, lower concentrations result in a decrease in blood pressure and stimulation of baroreceptor reflex mechanisms, which leads to decreased vasopressor activity and to decreased aldosterone secretion.

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Therapeutic Uses
/CLINICAL TRIALS/ ClinicalTrials.gov is a registry and results database of publicly and privately supported clinical studies of human participants conducted around the world. The Web site is maintained by the National Library of Medicine (NLM) and the National Institutes of Health (NIH). Each ClinicalTrials.gov record presents summary information about a study protocol and includes the following: Disease or condition; Intervention (for example, the medical product, behavior, or procedure being studied); Title, description, and design of the study; Requirements for participation (eligibility criteria); Locations where the study is being conducted; Contact information for the study locations; and Links to relevant information on other health Web sites, such as NLM's MedlinePlus for patient health information and PubMed for citations and abstracts for scholarly articles in the field of medicine. Benazepril is included in the database.
Lotensin is indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. ... It may be used alone or in combination with thiazide diuretics. /Included in US product label/
ACE inhibitors have been used in the management of heart failure, usually in conjunction with other agents such as cardiac glycosides, diuretics, and beta-blockers. /Angiotensin-converting enzyme (ACE) inhibitors; NOT included in US product label/
Both angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor antagonists have been shown to slow the rate of progression of renal disease in patients with diabetes mellitus and persistent albuminuria, and use of a drug from either class is recommended in such patients with modestly elevated (30-300 mg/24 hours) or higher (exceeding 300 mg/24 hours) levels of urinary albumin excretion. The usual precautions of ACE inhibitor or angiotensin II receptor antagonist therapy in patients with substantial renal impairment should be observed. /Angiotensin-converting enzyme (ACE) inhibitors; NOT included in US product label/
For more Therapeutic Uses (Complete) data for Benazepril (7 total), please visit the HSDB record page.

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Drug Warnings
/BOXED WARNING/ When pregnancy is detected, discontinue Lotensin as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus.
Rare angiotensin-converting enzyme (ACE) inhibitor-associated clinical syndrome manifested initially by cholestatic jaundice; may progress to fulminant hepatic necrosis and is potentially fatal. Patients receiving an ACE inhibitor, including benazepril, who develop jaundice or marked elevations of hepatic enzymes should discontinue the drug and receive appropriate monitoring.
Serum potassium should be monitored periodically in patients receiving Lotensin. Drugs that inhibit the renin-angiotensin system can cause hyperkalemia. Risk factors for the development of hyperkalemia include renal insufficiency, diabetes mellitus, and the concomitant use of potassium-sparing diuretics, potassium supplements and/or potassium-containing salt substitutes.
Adverse effects reported in greater than 1% of patients receiving benazepril include headache, dizziness, fatigue, somnolence, postural dizziness, nausea, and cough. Adverse effects reported in greater than 1% of patients receiving benazepril in fixed combination with hydrochlorothiazide include dizziness, fatigue, postural dizziness, headache, cough, hypertonia, vertigo, nausea, impotence, and somnolence. Adverse effects reported in greater than 1% of patients receiving benazepril in fixed combination with amlodipine include cough, headache, dizziness, and edema.
For more Drug Warnings (Complete) data for Benazepril (16 total), please visit the HSDB record page.

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Pharmacodynamics
Benazepril, an angiotensin-converting enzyme (ACE) inhibitor, is a prodrug which, when hydrolyzed by esterases to its active Benazeprilat, is used to treat hypertension and heart failure, to reduce proteinuria and renal disease in patients with nephropathies, and to prevent stroke, myocardial infarction, and cardiac death in high-risk patients. Benazepril and Benazeprilat inhibit angiotensin-converting enzyme (ACE) in human subjects and animals. ACE is a peptidyl dipeptidase that catalyzes the conversion of angiotensin I to the vasoconstrictor substance, angiotensin II. Angiotensin II also stimulates aldosterone secretion by the adrenal cortex.

C24H28N2O5

424.4895

424.199

86541-75-5

Benazepril hydrochloride;86541-74-4

5362124

Typically exists as solid at room temperature

1.3±0.1 g/cm3

691.2±55.0 °C at 760 mmHg

133-135 °C(lit.)

371.8±31.5 °C

0.0±2.3 mmHg at 25°C

1.608

3.86

2

6

10

31

619

2

C(N1C(=O)[C@@H](N[C@H](C(=O)OCC)CCC2C=CC=CC=2)CCC2C=CC=CC1=2)C(=O)O

XPCFTKFZXHTYIP-PMACEKPBSA-N

InChI=1S/C24H28N2O5/c1-2-31-24(30)20(14-12-17-8-4-3-5-9-17)25-19-15-13-18-10-6-7-11-21(18)26(23(19)29)16-22(27)28/h3-11,19-20,25H,2,12-16H2,1H3,(H,27,28)/t19-,20-/m0/s1

2-[(3S)-3-[[(2S)-1-ethoxy-1-oxo-4-phenylbutan-2-yl]amino]-2-oxo-4,5-dihydro-3H-1-benzazepin-1-yl]acetic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)