ADME/Tox: From Basics to Advanced – Metabolizing Enzymes, Transporters and Key Tool Compounds

Why is everyone talking about ADME/Tox?

Many drug candidates only reveal critical issues after they enter clinical trials:

• Some show excessive exposure, leading to serious toxicity;
• Some show insufficient exposure, failing to reach effective concentrations;
• Quite a few are forced to reduce the dose or even withdraw from the market due to drug–drug interactions (DDIs).

Regulatory agencies summarize it very clearly:

Unanticipated or poorly managed DDIs are one of the major causes of drug-related morbidity and drug withdrawal.

As a result, in modern drug development, absorption (A), distribution (D), metabolism (M), excretion (E) and toxicity (Tox) — collectively ADME/Tox — are now systematically evaluated at an early stage. Favorable ADME/Tox properties not only determine whether a compound can “become a drug”, but also directly impact clinical dose, dosing interval, combination regimens, and even the target patient population.

Key ADME/Tox Questions at a Glance

Dimension	Key question	Typical points of interest
A – Absorption	Can the drug actually be “taken up” by the body?	For oral drugs: can they efficiently cross the intestinal epithelium (high vs. low permeability)? Are they subject to efflux by intestinal transporters such as P-gp, BCRP, etc.?
D – Distribution	Where does the drug go in the body?	What is the plasma protein binding? Is the unbound fraction sufficient? Can it cross the blood–brain barrier (BBB)? Does it distribute to sensitive sites such as the placenta or breast milk?
M – Metabolism	How is the drug “broken down”?	Which enzymes primarily clear it: CYPs? UGTs? SULTs? Are pharmacologically active or toxic metabolites formed? Are there significant genetic polymorphisms (e.g. CYP2D6, CYP2C19) that drive interindividual exposure differences?
E – Excretion	How does the drug “leave” the body?	Is elimination mainly via the kidney (filtration + secretion + reabsorption) or via biliary excretion? Does active transport depend on OAT, OCT, MATE, OATP and other transporters?
Tox – Toxicity	Is the drug “safe”?	Key endpoints such as acute/chronic toxicity, hepatotoxicity, nephrotoxicity, cardiotoxicity, etc.; “exposure-driven toxicity” due to DDIs (e.g. marked AUC increase caused by inhibition of metabolizing enzymes or transporters).

Two Major Systems Shaping ADME/Tox

1. Drug-metabolizing enzymes: the CYP family as the key example

Among drug-metabolizing enzymes, the most important group is cytochrome P450 (CYP). Clinically, the following family members are of primary concern:

1. CYP3A4/5

Responsible for the metabolism of more than half of marketed drugs, and therefore a major “hot spot” for DDIs. CYP3A4/5 participates in the metabolism of over half of small-molecule drugs and is one of the main sources of enzyme-mediated DDIs.

2. CYP2D6

Exhibits pronounced genetic polymorphism; many antidepressants and antiarrhythmic agents are its substrates.

3. CYP2C9, CYP2C19, CYP2C8

Key metabolic pathways for anticoagulants, antipyretic analgesics, antiepileptics and certain antidiabetic drugs.

4. CYP1A2, CYP2B6, etc.

Also play critical roles for specific drugs.

For a new drug candidate, several fundamental questions must usually be addressed:

• Which CYP isoforms primarily metabolize it?
• Will it inhibit or induce these enzymes, thereby affecting other drugs?
• If the patient has impaired CYP function (e.g. CYP2D6 poor metabolizer), by how much will exposure increase?

This is exactly where CYP probe substrates and inhibitor tool compounds are used.

2. Transmembrane transporters: the ABC and SLC families

Over the past decade, the importance of transporters has gained increasing recognition. In their relevant guidelines, the FDA and EMA list the following transporters as “priority” targets when evaluating DDIs:

1. Efflux transporters (ABC family)

• P-gp (MDR1)
• BCRP (ABCG2)

2. Hepatic uptake transporters (SLC family)

• OATP1B1, OATP1B3

3. Renal transporters (SLC family)

• OAT1, OAT3, OCT2, MATE1, MATE2-K

These transporters determine whether a drug can enter hepatocytes, whether it is secreted into renal tubules, and whether it is effluxed back into the intestinal lumen. For example:

• Inhibition of OATP1B1/1B3 can markedly increase plasma concentrations of statins, raising the risk of myopathy and even rhabdomyolysis;
• Inhibition of OAT1/3 can reduce renal excretion of certain antiviral drugs and increase the risk of nephrotoxicity.

Therefore, for a new drug it is not enough to ask only “Is it a substrate of these transporters?” — it is equally important to ask “Will it inhibit them?”

Regulatory Perspective: From FDA Guidance to ICH M12

In 2020, the FDA issued its final guidance on in vitro drug–drug interactions (DDIs) mediated by CYP enzymes and transporters, providing a systematic framework for the design and interpretation of in vitro DDI studies.

In 2024, ICH released the M12 guideline “Drug Interaction Studies”, which harmonizes the design and interpretation of enzyme- and transporter-mediated DDI studies across both in vitro and clinical settings, exerting a major influence on global new drug development.

The overarching concept can be simplified into three steps:

1. Identify clearance pathways

Clarify which enzymes and/or transporters are primarily responsible for clearing the candidate drug.

2. Assess the risk as a “victim”

If these enzymes/transporters are markedly inhibited or induced by a comedication, will this lead to a several-fold increase in exposure?

3. Assess the risk as a “perpetrator”

Does the candidate drug itself strongly inhibit or induce key enzymes/transporters, thereby affecting the pharmacokinetics of co-administered drugs?

To answer these questions, the foundation lies in robust in vitro ADME/Tox methodologies and the use of appropriate tool compounds.

Tool Compounds: The “Reference Rulers” in ADME/Tox Assays

In ADME/Tox research, several terms are frequently used:

1. Probe substrate

A substrate that is relatively selective for a particular enzyme or transporter.

2. Index inhibitor/inducer

A strong inhibitor or inducer with a well-characterized clinical DDI profile and recommended in regulatory guidelines.

3. Positive/negative control

A reference compound used to demonstrate that the experimental system is “working properly”.

In essence, these “rulers” are all bioactive small-molecule tool compounds. Without them, it is difficult to determine whether an experimental system is reliable, and nearly impossible to bridge in vitro findings to clinical DDI risk. Tool compounds can be broadly grouped into three categories.

Category 1: CYP-Related Tool Compounds (Core Tools)

This category mainly addresses the questions:

“Which enzymes metabolize my drug? Will it inhibit or induce key CYP isoforms?”

1. Classic probe substrates

These compounds are commonly used in liver microsomes, recombinant enzymes, or cellular systems to measure the activity of individual CYP isoforms, for example:

• CYP2D6 probes – Certain β-adrenergic receptor blockers, bufuralol, etc.
• CYP2C19 probes – S-mephenytoin, selected proton pump inhibitors.
• CYP2C9 probes – Antipyretic analgesics or antiepileptics (e.g. phenytoin sodium, diclofenac).
• CYP1A2 probes – Theophylline and other xanthine derivatives.
• CYP2B6 probes – Bupropion.
• CYP2C8 probes – Repaglinide, thiazolidinedione antidiabetic agents.

When multiple probe substrates are added to the same system, a “CYP cocktail assay” can be performed, enabling simultaneous readout of activity changes across several CYP isoforms in a single experiment.

2. Typical inhibitors and inducers

In DDI assessment, a set of strong inhibitors and strong inducers is typically selected as controls. Examples include:

• CYP3A4 inhibitors – Certain azole antifungals and HIV protease inhibitors (e.g. ritonavir).
• CYP1A2 inhibitors – Fluvoxamine, furafylline.
• CYP2D6 inhibitors – Quinidine.
• CYP2C8 inhibitors – Gemfibrozil.
• Inducers – Rifampicin and some antiepileptic drugs, which strongly induce CYP3A, CYP2C and other isoforms.

These tool compounds generally have well-characterized clinical DDI data, allowing in vitro IC₅₀/Ki values to be meaningfully linked to changes in clinical AUC.

Category 2: Transporter Tool Compounds (Core Tools)

This category mainly addresses:

“Is my drug a substrate of these key transporters? Will it inhibit them?”

1. Classic substrates

Commonly used transporter substrates include:

• P-gp – Digoxin; certain anticancer drugs (e.g. vinca alkaloids, paclitaxel); loperamide, etc.
• BCRP – Topotecan, selected quinolones, estrogen metabolites, etc.
• OATP1B1/1B3 – Statins (e.g. lovastatin), bile acids and their analogues.
• OAT1/OAT3 – Antiviral nucleotide analogues (e.g. adefovir, cidofovir).
• OCT2/MATE – Cimetidine and other monovalent cationic drugs.

Using these substrates, cell-based or vesicular systems can be established to determine whether a candidate compound behaves as a substrate or inhibitor.

2. Selective inhibitors

To confirm that the observed transport is indeed mediated by a specific transporter—rather than passive diffusion or other proteins—highly selective inhibitors are required, for example:

• Probenecid – OAT1/3 inhibitor.
• Cimetidine – OCT2/MATE inhibitor.
• Verapamil, cyclosporin A – P-gp inhibitors.
• Ko143, fumitremorgin C, ML230 – Selective BCRP inhibitors.
• Certain estrogen metabolites, such as estrone 3-sulfate and estradiol-17-β-glucuronide – commonly used as endogenous OATP1B1/1B3 substrates for functional validation.

When addition of an inhibitor leads to a clear increase in intracellular substrate concentration (for efflux transporters) or a decrease (for uptake transporters), it indicates that the corresponding transporter is functionally involved.

Category 3: Toxicology and Signaling-Related Tool Compounds

ADME/Tox research is not limited to pharmacokinetic parameters; toxicological endpoints are equally critical. In in vitro systems, positive controls are required to confirm:

• That cells are capable of responding to injury;
• That the assay is sufficiently sensitive.

Common examples include:

1. Staurosporine

A broad-spectrum protein kinase inhibitor that induces apoptosis at low concentrations; the classic positive control in cytotoxicity/apoptosis assays.

2. Anticancer agents such as paclitaxel, topotecan, oxaliplatin

These are not only transporter substrates but also cytotoxic positive controls used in multidrug resistance models.

3. Ouabain and other cardiac glycosides

Used in cardiotoxicity evaluation and ion pump function assays.

4. GSH-depleting agents such as buthionine sulfoximine (BSO)

Employed to establish oxidative stress models and to assess the dependence of compounds on cellular antioxidant systems.

These tool compounds may not directly serve as probes for metabolizing enzymes or transporters, but they are highly important in the toxicology component of ADME/Tox research.

How to Select Appropriate Tool Compounds for Your Studies

1. Define the question first, then select the tools

(1) Want to know “Is my candidate metabolized by CYP2C19?”

→ Use a CYP2C19 probe substrate plus a CYP2C19 inhibitor in a competitive assay.

(2) Want to know “Is my drug a substrate of OATP1B1?”

→ Use OATP1B1-expressing cells together with a classic substrate (e.g. estrone sulfate) and selective inhibitors for comparison.

(3) Want to assess “Does it induce hepatotoxicity or apoptosis?”

→ Use staurosporine or a typical hepatotoxic drug as a positive control.

2. Prioritize “classic” tools that are regulator- and literature-endorsed

(1) These compounds frequently appear in guidelines, reviews, and methodological papers.

Their mechanisms are well-characterized and data are abundant, which greatly facilitates cross-study and peer comparison.

3. Match your experimental conditions

(1) Solubility – Does the compound need to be pre-dissolved in DMSO? Does the final solvent concentration affect cell viability or assay readouts?

(2) Stability – Is it prone to photodegradation or hydrolysis?

(3) Off-target effects – Some compounds hit multiple targets at higher concentrations, so concentration selection requires particular caution.

4. Turn tool compounds into routine “quality controls”

(1) Include fixed probe substrates and positive controls in every experiment to monitor system performance over time (e.g. Km, CLint, inhibition rate).

This supports methodological traceability and long-term data accumulation.

Example and Reference Tables of Common ADME/Tox Tool Compounds (Aladdin)

After introducing the basic concepts of metabolizing enzymes, transporters, and commonly used tool compounds in ADME/Tox research, we provide three example product tables corresponding to the above topics:

• CYP-related tool compound examples
• Transporter-related tool compound examples
• Toxicology and signaling-related tool compound examples

It should be emphasized that the compounds listed in these tables are only a subset of commonly used, representative tools, and do not cover all drugs or bioactive small molecules that can be applied in ADME/Tox studies. In actual selection, we recommend that you:

1. Align choices with your specific experimental objectives (e.g. target enzymes/transporters, system type, need for clinical DDI comparators, etc.), and

2. Use these representative tool compounds as a starting set to further expand and refine your own tool panel.

Category Definitions

1. Core tools

Classic CYP probe substrates/inhibitors; transporter substrates and inhibitors frequently recommended in regulatory guidelines; and compounds that are commonly used as ADME/Tox reference standards in the literature.

2. Extended – ADME/Tox-related

Compounds closely associated with renal transport, antiviral drugs, anticancer drugs, OATP/OAT-mediated processes, and DDIs, but used at a slightly lower frequency than core tools.

3. Extended – Toxicology / Signaling / Other

Compounds mainly used in cytotoxicity, signaling pathway, cardiotoxicity, or oxidative stress models and other toxicological assays.

Core Tools

Category	CAS No.	Product No.	Name	Grade / Purity	Typical ADME/Tox Application
Core tool	120202-66-6	S129544	(S)-(+)-Clopidogrel sulfate	≥98%	CYP2C19-dependent prodrug; commonly used as a sensitive substrate in CYP2C19 metabolism, polymorphism, and DDI studies.
Core tool	70989-04-7	M335343	(S)-(+)-Mephenytoin	≥98%	Classic CYP2C19 probe substrate used for CYP2C19 enzyme activity and phenotyping studies.
Core tool	60398-91-6	B650281	Bufuralol hydrochloride	—	Common CYP2D6 probe substrate used for CYP2D6 activity and inhibition studies.
Core tool	630-93-3	D107846	Phenytoin sodium	≥98%	Representative CYP2C9/2C19 substrate used to evaluate metabolic rate and enzyme selectivity.
Core tool	31677-93-7	B129446	Bupropion hydrochloride	≥98% (HPLC)	Classic CYP2B6 probe substrate used to study CYP2B6 activity and genetic polymorphism.
Core tool	95-25-0	C129514	Chlorzoxazone	Moligand™, ≥98%	Classic CYP2E1 probe substrate used to characterize CYP2E1 metabolic capacity and induction/inhibition.
Core tool	51481-61-9	C102301	Cimetidine	Moligand™, ≥99%	OCT2/MATE inhibitor and multi-CYP inhibitor, commonly used in renal transport and enzyme-inhibition DDI studies.
Core tool	59865-13-3	C106893	Cyclosporin A	Moligand™, ≥98%	Classic P-gp/OATP inhibitor and CYP3A4 substrate used in high DDI-risk assessment.
Core tool	15307-79-6	D129332	Diclofenac sodium	≥99%	Common CYP2C9 substrate used for CYP2C9 activity characterization and inhibition assays.
Core tool	153653-30-6	D648708	Dofequidar fumarate	≥98%	P-gp/MDR inhibitor used in multidrug resistance and efflux transporter function studies.
Core tool	143664-11-3	E126576	Elacridar	Moligand™, ≥98%	Potent dual P-gp/BCRP inhibitor used in blood–brain barrier and efflux transporter inhibition studies.
Core tool	153439-40-8	F129253	Fexofenadine hydrochloride	≥98%	Dual OATP/P-gp substrate commonly used as a probe for hepatic uptake and efflux transporters.
Core tool	86386-73-4	E129360	Fluconazole	Moligand™, ≥98%	CYP2C9/3A inhibitor used as a strong inhibitor control in DDI studies.
Core tool	61718-82-9	F129671	Fluvoxamine maleate	≥98%	Potent CYP1A2/CYP2C19 inhibitor commonly used in enzyme-selective inhibition studies.
Core tool	118974-02-0	F492230	Fumitremorgin C	≥95%	Selective BCRP (ABCG2) inhibitor used for BCRP functional validation and DDI studies.
Core tool	80288-49-9	F276109	Furafylline	≥98%	Selective mechanism-based CYP1A2 inhibitor used for CYP1A2-specific inhibition studies.
Core tool	25812-30-0	G129727	Gemfibrozil	Moligand™, ≥99%	Potent CYP2C8 inhibitor that also affects OATP1B1; classic DDI control (e.g. with repaglinide).
Core tool	65277-42-1	K475027	Ketoconazole	Moligand™, ≥99% (EP, titration)	Classic strong CYP3A4 inhibitor and early FDA-recommended index inhibitor.
Core tool	461054-93-3	K120134	Ko143 (BCRP inhibitor)	Moligand™, ≥98%	Highly potent and selective BCRP inhibitor used in efflux transporter inhibition and as an internal/external control.
Core tool	1776055-05-0	M646740	ML230	≥99%	Novel ABCG2/BCRP inhibitor used in more refined BCRP functional studies.
Core tool	151767-02-1	M129586	Montelukast sodium hydrate	≥99%	Inhibits hepatic uptake transporters such as OATP2B1 and also affects CYP2C8; commonly used in DDI models.
Core tool	73590-58-6	O118724	Omeprazole	Moligand™, ≥98%	CYP2C19/3A4 substrate and weak inhibitor commonly used in phenotyping, induction, and DDI studies.
Core tool	33069-62-4	P106868	Paclitaxel	Moligand™, analytical standard, ≥99%	Typical P-gp substrate also metabolized by CYP2C8/3A4; used in multidrug resistance and CYP-related studies.
Core tool	50-55-5	R101672	Reserpine	Moligand™, analytical standard, ≥99.5%	Classic vesicular monoamine transporter (VMAT) inhibitor that also affects certain transporters; used in CNS and toxicology models.
Core tool	135062-02-1	R129561	Repaglinide	Moligand™, ≥99%	Classic OATP1B1/1B3 and CYP2C8 substrate widely used in DDI and PBPK modeling.
Core tool	155213-67-5	R126586	Ritonavir	Moligand™, ≥98%	Extremely strong CYP3A4 and transporter inhibitor used as a pharmacokinetic enhancer and in DDI studies.
Core tool	117-39-5	Q111273	Quercetin	Moligand™, analytical standard, ≥98.5%	Natural product commonly used as an OATP/BCRP inhibitor and transporter inhibition control.
Core tool	56-54-2	Q109702	Quinidine	Moligand™, ≥98%, 5–15% dihydroquinidine	Potent CYP2D6 inhibitor and P-gp inhibitor; classic reference compound for DDI studies.
Core tool	57-66-9	P129440	Probenecid	Moligand™, ≥98%	Classic OAT1/OAT3 inhibitor used in renal tubular secretion and renal DDI studies.
Core tool	33069-62-4	P106869	Paclitaxel	Moligand™, ≥99%	High-affinity P-gp substrate commonly used in MDR models and transport studies.
Core tool	149845-06-7	S1423002	Saquinavir mesylate	≥99%	HIV protease inhibitor; classic CYP3A4 and transporter substrate used in DDI research.
Core tool	50679-08-8	T137617	Terfenadine	Moligand™, ≥98%	Well-known CYP3A4-related arrhythmogenic DDI case drug used in safety and enzyme inhibition studies.
Core tool	119413-54-6	T103153	Topotecan hydrochloride	Analytical standard, ≥99% (HPLC)	BCRP/P-gp substrate used in efflux transporter function assays and tumor toxicity studies.
Core tool	143-67-9	V100992	Vinblastine sulfate	Analytical standard, ≥97% (HPLC)	Typical P-gp substrate used in MDR and transporter-related ADME research.
Core tool	152-11-4	V111249	Verapamil hydrochloride	≥99%	P-gp substrate/inhibitor and CYP3A4 substrate; classic reference compound for transporter and DDI studies.
Core tool	36622-28-3	V651432	(S)-Verapamil hydrochloride	≥99%	Enantiomerically pure P-gp inhibitor/substrate, more commonly used than the racemate in detailed transporter studies.

Extended – ADME/Tox-Related Tools (Renal Transport, Antivirals, Anticancer, etc.)

Category	CAS No.	Product No.	Name	Grade / Purity	Typical ADME/Tox Application
Extended-ADME/Tox	106941-25-7	A165714	Adefovir	≥98% (HPLC)	Nephrotoxic nucleotide analogue used in OAT1/3-mediated uptake and nephrotoxicity models.
Extended-ADME/Tox	188062-50-2	A129792	Abacavir sulfate	≥99%	Antiviral nucleoside analogue for HIV used in hepatic uptake transporter and renal excretion studies.
Extended-ADME/Tox	59277-89-3	A126073	Acyclovir	Moligand™, ≥99%	Primarily renally excreted antiviral drug used in renal transport and nephrotoxicity evaluation.
Extended-ADME/Tox	2016-88-8	A131615	Amiloride hydrochloride hydrate	≥98%	Related to ENaC and cation transport in renal collecting ducts; used in renal excretion and electrolyte balance studies.
Extended-ADME/Tox	30516-87-1	A122924	3′-Azido-3′-deoxythymidine (AZT)	Moligand™, ≥98% (HPLC)	Classic nucleoside analogue used in mitochondrial toxicity, transporter, and metabolism studies.
Extended-ADME/Tox	28395-03-1	B129942	Bumetanide	Moligand™, ≥98%	Loop diuretic involved in renal and ion transport; provides a reference for studies on renal excretion.
Extended-ADME/Tox	113852-37-2	C126447	Cidofovir	≥98%	Antiviral drug with pronounced nephrotoxicity used in OAT1/3 and renal safety studies.
Extended-ADME/Tox	64-86-8	C106739	Colchicine	Moligand™, analytical standard, ≥99% (HPLC)	One of the P-gp substrates; also used in liver and bone marrow toxicity models.
Extended-ADME/Tox	61825-94-3	O124003	Oxaliplatin	≥99%	Platinum-based anticancer drug used in neurotoxicity, nephrotoxicity, and DNA cross-link damage models.
Extended-ADME/Tox	82410-32-0	G129641	Ganciclovir	≥99%	Anti-CMV nucleoside analogue used in renal/bone marrow toxicity and transporter studies.
Extended-ADME/Tox	112529-15-4	P121082	Pioglitazone hydrochloride	≥98%	PPARγ agonist and CYP2C8 substrate used in DDI and liver safety studies.
Extended-ADME/Tox	122320-73-4	R128083	Rosiglitazone	Moligand™, ≥98%	Mainly metabolized by CYP2C8; used in CYP2C8-related DDI research.
Extended-ADME/Tox	135062-02-1	R129561	Repaglinide	Moligand™, ≥99%	Cross-substrate for OATP1B1 and CYP2C8; important DDI model drug.
Extended-ADME/Tox	75330-75-5	L107708	Lovastatin	Moligand™, analytical standard, ≥98%	OATP1B1/1B3 and CYP3A4 substrate commonly used in bile excretion and hepatic uptake transporter studies.
Extended-ADME/Tox	104987-11-3	T101159	Tacrolimus (anhydrous) (FK506)	Moligand™, analytical standard, ≥98%	CYP3A4/P-gp substrate with marked interindividual variability and high DDI risk; frequently used as a PK target in transplant drug research.
Extended-ADME/Tox	147221-93-0	D134807	Delavirdine mesylate	≥98% (HPLC)	NNRTI-type CYP3A inhibitor used in CYP3A inhibition and DDI studies.
Extended-ADME/Tox	159989-65-8	N137745	Nelfinavir mesylate	≥98%	HIV protease inhibitor and CYP3A substrate/inhibitor used in DDI models.
Extended-ADME/Tox	61825-94-3	O124003	Oxaliplatin	≥99%	Anticancer drug used in neurotoxicity and nephrotoxicity evaluation.

Extended – Toxicology / Signaling / Other Models

Category	CAS No.	Product No.	Name	Grade / Purity	Typical ADME/Tox Application
Extended-Tox/signaling	11018-89-6	G129536	Ouabain (g-Strophanthin)	Moligand™, ≥98%	Cardiac glycoside commonly used in cardiotoxicity and ion pump function models.
Extended-Tox/signaling	20624-25-3	S104926	Sodium diethyldithiocarbamate trihydrate	AR, ≥99%	Metal chelator and free radical scavenger used in oxidative stress and metal toxicity studies.
Extended-Tox/signaling	299442-43-6	N276064	Adenylate cyclase type V inhibitor	Moligand™, ≥98%	AC5 inhibitor used in cAMP signaling and cardiovascular toxicology models.
Extended-Tox/signaling	62996-74-1	S102392	Staurosporine	Moligand™, ≥98%	Broad-spectrum protein kinase inhibitor widely used as a positive control in apoptosis/cytotoxicity assays.
Extended-Tox/signaling	50-55-5	R101672	Reserpine	Moligand™, analytical standard, ≥99.5%	Monoamine-depleting agent used in CNS toxicity and transporter inhibition models.
Expanded – Tox/Signaling	88889-14-9	F129333	Fosinopril Sodium	≥99%	Prodrug ACE inhibitor used as a RAAS-blocking positive control in cardiovascular disease models (e.g., hypertension, heart failure); suitable for evaluating the effects of RAAS inhibition on cardiac/vascular remodeling, oxidative stress, and kidney injury–related toxicological endpoints.

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