Angiotensin-converting enzyme (ACE) inhibitor ramipril (HOE-498) has an IC50 of 5 nM[1]. However, in endothelial cells expressing an S1270A ACE mutant or in ACE-deficient cells, ramipril (HOE-498) is unable to activate JNK or boost the nuclear accumulation of c-Jun. Instead, it increases the activity of ACE-associated CK2 and the phosphorylation of ACE Ser1270 in cultured endothelial cells. Long-term Ramipril use raises ACE expression in mouse lung in vivo and primary cultures of human endothelial cells, a phenomenon that can be avoided by pretreating with the JNK inhibitor SP600125[2].

In contrast to the apoptosis effect in vitro, chronic in vivo administration of Ramipril (HOE-498) to rats at a dosage that has similar hypotensive effects in vitro HUVECs considerably lowers the rate of LPS-induced apoptosis relative to the other ACE inhibitors[3 [4].

Absorption, Distribution and Excretion
The extent of absorption is at least 50-60%.. Food decreases the rate of absorption from the GI tract without affecting the extent of absorption. The absolute bioavailabilities of ramipril and ramiprilat were 28% and 44%, respectively, when oral administration was compared to intravenous administration. The serum concentration of ramiprilat was unchanged when capsules were opened and the contents dissolved in water, dissolved in apple juice, or suspended in apple sauce.
Following oral administration, about 60% of the dose is eliminated in the urine as unchanged ramipril (<2%) and its metabolites. About 40% of the dose is found in the feces, representing both unabsorbed drug and drugs and metabolites eliminated via biliary excretion. The urinary excretion of ramipril may be reduced in patients with impaired renal function.
The renal clearance of ramipril and ramiprilat was reported to be 7.2 and 77.4 mL/min/1.73m². The mean renal clearance of ramipril and ramiprilat is reported to be 10.7 and 126.8 mL/min in healthy elderly patients with normal renal function, additionally the Cmax of ramiprilat is approximately 20% higher in this population. While the pharmacokinetics of ramipril appear unaffected by reduced renal function, the plasma concentration and half-life of ramiprilat are increased. In patient's with hepatic failure the concentration of ramipril is initially increased while the tmax of ramiprilat is prolonged due to a reduced ability to metabolize the drug. However, steady state concentrations of ramiprilat are the same in hepatic failure as in healthy patients.
/MILK/ Ingestion of a single 10 mg oral dose of ramipril resulted in undetectable amounts of ramipril and its metabolites in breast milk.
Following oral administration of ramipril, peak plasma concentrations (Cmax) of ramipril are reached within 1 hour. The extent of absorption is at least 50% to 60%, and is not significantly influenced by the presence of food in the gastrointestinal tract, although the rate of absorption is reduced.
Plasma concentrations of ramiprilat decline in a triphasic manner (initial rapid decline, apparent elimination phase, terminal elimination phase). The initial rapid decline, which represents distribution of the drug into a large peripheral compartment and subsequent binding to both plasma and tissue ACE, has a half-life of 2 to 4 hours. Because of its potent binding to ACE and slow dissociation from the enzyme, ramiprilat shows two elimination phases. The apparent elimination phase corresponds to the clearance of free ramiprilat and has a half-life of 9 to 18 hours. The terminal elimination phase has a prolonged half-life (>50 hours) and probably represents the binding/dissociation kinetics of the ramiprilat/ACE complex. It does not contribute to the accumulation of the drug. After multiple daily doses of ramipril 5 mg to 10 mg, the half-life of ramiprilat concentrations within the therapeutic range was 13 to 17 hours. /Ramiprilat/
Plasma concentrations of ramipril and ramiprilat increase with increased dose, but are not strictly dose-proportional. The 24-hour AUC for ramiprilat, however, is dose-proportional over the 2.5 mg to 20 mg dose range. The absolute bioavailabilities of ramipril and ramiprilat were 28% and 44%, respectively, when 5 mg of oral ramipril was compared with the same dose of ramipril given intravenously.
For more Absorption, Distribution and Excretion (Complete) data for Ramipril (7 total), please visit the HSDB record page.

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Metabolism / Metabolites
Hepatic metabolism accounts for 75% of total ramipril metabolism. 25% of hepatic metabolism produces the active metabolite ramiprilat via liver esterase enzymes. 100% of renal metabolism converts ramipril to ramiprilat. Other metabolites, diketopiperazine ester, the diketopiperazine acid, and the glucuronides of ramipril and ramiprilat, are inactive.
Cleavage of the ester group (primarily in the liver) converts ramipril to its active diacid metabolite, ramiprilat. Peak plasma concentrations of ramiprilat are reached 2 to 4 hours after drug intake. The serum protein binding of ramipril is about 73% and that of ramiprilat about 56%; in vitro, these percentages are independent of concentration over the range of 0.01 ug/mL to 10 mcg/mL.
After oral administration to dogs, ramipril is rapidly converted via de-esterification into ramiprilat. Bioavailability of ramiprilat after a dose of 0.25 mg/kg per day of ramipril is approximately 6.7%.
Ramipril is a prodrug and has little pharmacologic activity until hydrolyzed in the liver to ramiprilat.
Ramipril is almost completely metabolized to ramiprilat, which has about 6 times the angiotensin-converting enzyme (ACE) inhibitory activity of ramipril, and to the diketopiperazine ester, the diketopiperazine acid, and the glucuronides of ramipril and ramiprilat, all of which are inactive.

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Biological Half-Life
Plasma concentrations of ramiprilat decline in a triphasic manner. Initial rapid decline represents distribution into tissues and has a half life of 2-4 hours. The half life of the apparent elimination phase is 9-18 hours, which is thought to represent clearance of free drug. The half-life of the terminal elimination phase is > 50 hours and thought to represent clearance of drug bound to ACE due to its slow dissociation. The half life of ramiprilat after multiple daily doses (MDDs) is dose-dependent, ranging from 13-17 hours with 5-10 mg MDDs to 27-36 hours for 2.5 mg MDDs.
Plasma concentrations of ramiprilat /metabolite of ramipril/ decline in a triphasic manner (initial rapid decline, apparent elimination phase, terminal elimination phase). The initial rapid decline, which represents distribution of the drug into a large peripheral compartment and subsequent binding to both plasma and tissue ACE, has a half-life of 2 to 4 hours. Because of its potent binding to ACE and slow dissociation from the enzyme, ramiprilat shows two elimination phases. The apparent elimination phase corresponds to the clearance of free ramiprilat and has a half-life of 9 to 18 hours. The terminal elimination phase has a prolonged half-life (>50 hours) and probably represents the binding/dissociation kinetics of the ramiprilat/ACE complex. It does not contribute to the accumulation of the drug. After multiple daily doses of ramipril 5 mg to 10 mg, the half-life of ramiprilat concentrations within the therapeutic range was 13 to 17 hours. /Ramiprilat/

Toxicity Summary
IDENTIFICATION AND USE: Ramipril is a prodrug and has little pharmacologic activity until hydrolyzed in the liver to ramiprilat. It is an angiotensin-converting enzyme (ACE) inhibitor indicated for the treatment of hypertension. It is also used for stable patients with demonstratable congestive heart failure within the first few days of sustaining acute myocardial infarction. HUMAN STUDIES: Rare ACE inhibitor-associated clinical syndrome manifested initially by cholestatic jaundice may occur. It may progress to fulminant hepatic necrosis and is potentially fatal. Patients receiving an ACE inhibitor, including ramipril, who develop jaundice or marked elevations in hepatic enzymes should discontinue the drug and receive appropriate monitoring. Sensitivity reactions, including anaphylactic reactions and angioedema (including laryngeal or tongue edema) are potentially fatal. Head and neck angioedema involving the tongue, glottis, or larynx may cause airway obstruction. If laryngeal stridor or angioedema of the face, tongue, or glottis occurs, ramipril should be discontinued and appropriate therapy (e.g., epinephrine) should be initiated immediately. 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. When pregnancy is detected, discontinue ramipril as soon as possible. No mutagenic activity was detected in the unscheduled DNA synthesis in a human cell line. ANIMAL STUDIES: No evidence of a tumorigenic effect was found when ramipril was given by gavage to rats for up to 24 months at doses of up to 500 mg/kg/day or to mice for up to 18 months at doses of up to 1000 mg/kg/day. A study in rats with dosages as great as 500 mg/kg/day did not produce adverse effects on fertility. Kidney organogenesis and functional development continue well into the postnatal period in the rat. A within-litter design was used to characterize renal susceptibility to an ACE inhibitor during the third week of life in rats. There were no treatment-related effects in rats dosed on PND 21. Following dosing on PND 14, dose-related increases were noted in mean serum urea nitrogen and/or creatinine levels on PND 17, but these measures recovered by PND 28. The interim changes were accompanied by macroscopic and microscopic changes in the kidneys on PND 17, including tubular hypoplasia, renal papillary edema, cortical tubular dilatation, hydronephrosis (pelvic dilatation) and tubular basophilia; renal anatomic changes were still evident and more severe on PND 28, 14 days after dosing. No mutagenic activity was detected in the Ames test in bacteria, the micronucleus test in mice or a forward gene-mutation assay in a Chinese hamster ovary cell line.

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

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Because no information is available on the use of ramipril during breastfeeding, an alternate drug may be preferred, especially while nursing a newborn or preterm infant.
◉ 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
Protein binding of ramipril is about 73% and that of ramiprilat about 56%. Protein binding is independent of concentration over the range of 0.1μg/mL-10μg/mL

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Interactions
In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function, co-administration of non-ateroidal anti-inflammatory drugs (NSAIDs), including selective cyclooxygenase-2 (COX-2) inhibitors, with angiotensin-converting enzyme (ACE) inhibitors, including ramipril, may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible. Monitor renal function periodically in patients receiving ramipril and NSAID therapy. The antihypertensive effect of ACE inhibitors, including ramipril, may be attenuated by NSAIDs.
Increased serum lithium levels and symptoms of lithium toxicity have been reported in patients receiving ACE inhibitors during therapy with lithium; therefore, frequent monitoring of serum lithium levels is recommended. If a diuretic is also used, the risk of lithium toxicity may be increased.
Coadministration of ramipril with other drugs that raise serum potassium levels may result in hyperkalemia. Monitor serum potassium in such patients.
Patients on diuretics, especially those in whom diuretic therapy was recently instituted, may occasionally experience an excessive reduction of blood pressure after initiation of therapy with ramipril. The possibility of hypotensive effects with ramipril can be minimized by either decreasing or discontinuing the diuretic or increasing the salt intake prior to initiation of treatment with ramipril. If this is not possible, reduce the starting dose.

[1]. Combined blockade of AT1-receptors and ACE synergistically potentiates antihypertensive effects in SHR. J Hypertens, 2004. 22(3): p. 611-8.

[2]. Stevens, B.R., M.I. Phillips, and A. Fernandez, Ramipril inhibition of rabbit (Oryctolagus cuniculus) small intestinal brush border membrane angiotensin converting enzyme. Comp Biochem Physiol C, 1988. 91(2): p. 493-7.

[3]. Angiotensin-converting enzyme is involved in outside-in signaling in endothelial cells. Circ Res, 2004. 94(1): p. 60-7.

[4]. Differences in the effect of angiotensin-converting enzyme inhibitors on the rate of endothelial cell apoptosis: in vitro and in vivo studies. Cardiovasc Drugs Ther, 2007. 21(6): p. 423-9.

Therapeutic Uses
Angiotensin-Converting Enzyme Inhibitors; Antihypertensive Agents
/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. Ramipril is included in the database.
Ramipril capsules are 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. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes including this drug. ... Ramipril capsules may be used alone or in combination with thiazide diuretics. /Included in US product label/
Ramipril capsules are indicated in stable patients who have demonstrated clinical signs of congestive heart failure within the first few days after sustaining acute myocardial infarction. Administration of ramipril capsules to such patients have been shown to decrease the risk of death (principally cardiovascular death) and to decrease the risks of failure-related hospitalization and progression to severe/resistant heart failure. /Included in US product label/
For more Therapeutic Uses (Complete) data for Ramipril (8 total), please visit the HSDB record page.

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Drug Warnings
/BOXED WARNING/ When pregnancy is detected, discontinue ramipril as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus.
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. When pregnancy is detected, discontinue ramipril as soon as possible. These adverse outcomes are usually associated with use of these drugs in the second and third trimester of pregnancy. Most epidemiologic studies examining fetal abnormalities after exposure to antihypertensive use in the first trimester have not distinguished drugs affecting the renin-angiotensin system from other antihypertensive agents. Appropriate management of maternal hypertension during pregnancy is important to optimize outcomes for both mother and fetus.
Angiotensin-converting enzyme (ACE) inhibitors can cause fetal and neonatal morbidity and mortality when used in pregnancy during the second and third trimesters. ACE inhibitors also increase the risk of major congenital malformations when administered during the first trimester of pregnancy. Discontinue as soon as possible when pregnancy is detected, unless continued use is considered lifesaving. Nearly all women can be transferred successfully to alternative therapy for the remainder of their pregnancy. /Angiotensin-converting enzyme (ACE) inhibitors/
Rare angiotensin-converting enzyme (ACE) inhibitor-associated clinical syndrome manifested initially by cholestatic jaundice may occur; may progress to fulminant hepatic necrosis and is potentially fatal. Patients receiving an ACE inhibitor, including ramipril, who develop jaundice or marked elevations in hepatic enzymes should discontinue the drug and receive appropriate monitoring.
For more Drug Warnings (Complete) data for Ramipril (18 total), please visit the HSDB record page.

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Pharmacodynamics
Ramipril is an ACE inhibitor similar to benazepril, fosinopril and quinapril. It is an inactive prodrug that is converted to ramiprilat in the liver, the main site of activation, and kidneys. Ramiprilat confers blood pressure lowing effects by antagonizing the effect of the RAAS. The RAAS is a homeostatic mechanism for regulating hemodynamics, water and electrolyte balance. During sympathetic stimulation or when renal blood pressure or blood flow is reduced, renin is released from the granular cells of the juxtaglomerular apparatus in the kidneys. In the blood stream, renin cleaves circulating angiotensinogen to ATI, which is subsequently cleaved to ATII by ACE. ATII increases blood pressure using a number of mechanisms. First, it stimulates the secretion of aldosterone from the adrenal cortex. Aldosterone travels to the distal convoluted tubule (DCT) and collecting tubule of nephrons where it increases sodium and water reabsorption by increasing the number of sodium channels and sodium-potassium ATPases on cell membranes. Second, ATII stimulates the secretion of vasopressin (also known as antidiuretic hormone or ADH) from the posterior pituitary gland. ADH stimulates further water reabsorption from the kidneys via insertion of aquaporin-2 channels on the apical surface of cells of the DCT and collecting tubules. Third, ATII increases blood pressure through direct arterial vasoconstriction. Stimulation of the Type 1 ATII receptor on vascular smooth muscle cells leads to a cascade of events resulting in myocyte contraction and vasoconstriction. In addition to these major effects, ATII induces the thirst response via stimulation of hypothalamic neurons. ACE inhibitors inhibit the rapid conversion of ATI to ATII and antagonize RAAS-induced increases in blood pressure. ACE (also known as kininase II) is also involved in the enzymatic deactivation of bradykinin, a vasodilator. Inhibiting the deactivation of bradykinin increases bradykinin levels and may sustain the effects of ramiprilat by causing increased vasodilation and decreased blood pressure.

C23H32N2O5

416.51

416.231

87333-19-5

Ramipril-d5;1132661-86-9;Ramipril-d3;2673269-81-1

5362129

White to off-white solid powder

1.2±0.1 g/cm3

616.2±55.0 °C at 760 mmHg

106-108°C

326.4±31.5 °C

0.0±1.9 mmHg at 25°C

1.556

3.41

2

6

10

30

619

5

CCOC(=O)[C@H](CCC1=CC=CC=C1)N[C@@H](C)C(=O)N2[C@H]3CCC[C@H]3C[C@H]2C(=O)O

HDACQVRGBOVJII-JBDAPHQKSA-N

InChI=1S/C23H32N2O5/c1-3-30-23(29)18(13-12-16-8-5-4-6-9-16)24-15(2)21(26)25-19-11-7-10-17(19)14-20(25)22(27)28/h4-6,8-9,15,17-20,24H,3,7,10-14H2,1-2H3,(H,27,28)/t15-,17-,18-,19-,20-/m0/s1

(2S,3aS,6aS)-1-[(2S)-2-[[(2S)-1-ethoxy-1-oxo-4-phenylbutan-2-yl]amino]propanoyl]-3,3a,4,5,6,6a-hexahydro-2H-cyclopenta[b]pyrrole-2-carboxylic 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)

Solubility in Formulation 1: ≥ 3.25 mg/mL (7.80 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 400 μL of PEG300 and mix evenly; then add 50 μL of Tween-80 to the above solution and mix evenly; then add 450 μL of normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 3.25 mg/mL (7.80 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
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.

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Solubility in Formulation 3: ≥ 3.25 mg/mL (7.80 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 32.5 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 30% PEG400+0.5% Tween80+5% Propylene glycol: 30 mg/mL

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Solubility in Formulation 5: 20 mg/mL (48.02 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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