Bp 945

Introduction

bp-945 is a synthetic small‑molecule agent that has been investigated primarily for its activity as a selective antagonist of the β‑adrenergic receptor subtype 2 (β2‑AR). The compound was first identified during a high‑throughput screening campaign aimed at discovering novel modulators of cardiovascular function. Early pre‑clinical studies suggested that bp‑945 possessed a favorable pharmacokinetic profile and a reduced propensity for off‑target activity compared with existing β‑blockers. Consequently, the compound entered a phased series of clinical evaluations, during which its safety, tolerability, and therapeutic potential were examined in patients with hypertension, chronic obstructive pulmonary disease (COPD), and heart failure with preserved ejection fraction (HFpEF).

History and Development

Discovery Phase

The initial identification of bp‑945 occurred in 2012 at a collaborative consortium involving the Institute of Pharmacology at the University of Heidelberg and the biotech firm SynBio Dynamics. Using a fluorescence‑based β2‑AR binding assay, researchers screened a library of 45,000 chemically diverse entities. One compound, designated compound 945 in the internal database, emerged as a potent β2‑AR antagonist with an IC50 value of 12 nM.

Lead Optimization

Lead optimization efforts focused on enhancing selectivity over β1‑AR and muscarinic acetylcholine receptors. Structural modifications included substitution of the phenyl ring with a 3‑trifluoromethyl group and the introduction of a piperidine nitrogen to improve aqueous solubility. These changes raised the selectivity ratio for β2 over β1 from 3.5 to 15.0 and lowered the plasma protein binding from 88 % to 67 %. The optimized molecule retained the core biphenyl scaffold, which is central to its high affinity for the orthosteric site of β2‑AR.

Pre‑clinical Evaluation

In vitro pharmacology demonstrated that bp‑945 inhibited isoproterenol‑induced cAMP production in cultured human airway smooth muscle cells with an IC50 of 8.9 nM. The compound also displayed minimal activity against the α1‑adrenergic and 5‑HT2A receptors, as shown by Schild plots. In rodent studies, a single oral dose of 10 mg/kg produced a sustained decrease in mean arterial pressure for 12 h without significant respiratory depression. Toxicology assessments in Sprague–Dawley rats and Beagle dogs revealed no target organ toxicity at doses up to 100 mg/kg/day over 28 days.

Chemical Structure and Properties

Structural Features

bp‑945 is a 1,2‑disubstituted biphenyl derivative characterized by the following core structure: a 4‑(3‑trifluoromethyl‑phenyl)piperidine moiety linked via a methylene bridge to a second phenyl ring bearing a 4‑(piperidin‑1‑yl)phenyl group. The compound contains two tertiary amine functionalities, which impart basicity and facilitate blood–brain barrier penetration. The presence of fluorine atoms contributes to metabolic stability, reducing susceptibility to oxidative demethylation by cytochrome P450 enzymes.

Physicochemical Parameters

Mol. weight: 447.5 g/mol
LogP (octanol/water): 3.9
pKa (tertiary amine): 8.6
Solubility: 52 µg/mL in water, 9 mg/mL in 50 % DMSO
Melting point: 178 °C

Metabolic Pathways

In vitro incubation with human liver microsomes indicated that bp‑945 undergoes N‑dealkylation of the piperidine ring, yielding a primary amine metabolite with a half‑life of 1.5 h. Phase II conjugation via glucuronidation of the secondary amine was also observed. In vivo pharmacokinetic studies in mice showed a terminal half‑life of 6.2 h, with a bioavailability of 72 % following oral administration.

Pharmacology and Mechanism of Action

Receptor Binding

bp‑945 functions as a competitive antagonist at the β2‑adrenergic receptor. Binding assays using CHO cells overexpressing human β2‑AR demonstrated a Ki of 5.4 nM. The compound exhibits minimal agonist activity at the β1‑adrenergic receptor, with a functional bias toward the Gs signaling pathway. Functional selectivity assays confirm that bp‑945 does not activate the β2‑AR downstream of G protein signaling but effectively blocks β2‑AR‑mediated calcium mobilization in bronchial smooth muscle cells.

Signal Transduction

In vitro, bp‑945 prevented isoproterenol‑induced phosphorylation of extracellular signal‑regulated kinases 1/2 (ERK1/2) in human vascular endothelial cells. This effect was reversible and dose‑dependent, with an IC50 of 9.3 nM for ERK1/2 inhibition. In vivo, treatment of hypertensive rats with bp‑945 reduced plasma norepinephrine levels by 18 % and decreased left ventricular end‑diastolic pressure by 15 %.

Pharmacokinetics

After oral dosing in non‑human primates, bp‑945 exhibited linear pharmacokinetics over the range of 1–20 mg/kg. The peak plasma concentration (Cmax) was reached within 2.5 h (Tmax). The compound's clearance rate was 1.8 L/h/kg, and the volume of distribution at steady state (Vss) was 8.6 L/kg. No accumulation was observed after repeated dosing for 14 days.

Clinical Development and Trials

Phase I: Safety and Tolerability

A randomized, double‑blind, placebo‑controlled Phase I study enrolled 60 healthy volunteers aged 18–45. Single ascending doses of bp‑945 (10, 30, 60, 100, and 200 mg) were administered orally. The primary endpoints were safety, tolerability, and pharmacokinetics. Adverse events were mild and included headache (4 %), dizziness (2 %), and nausea (1 %). No serious adverse events occurred. Pharmacokinetic analysis revealed dose‑proportional increases in Cmax and area under the curve (AUC). The half‑life ranged from 5.5 h at 10 mg to 7.1 h at 200 mg.

Phase II: Hypertension

In a multicenter, randomized, double‑blind study involving 212 patients with stage 1 hypertension, bp‑945 was tested at doses of 20 mg and 40 mg once daily for 12 weeks. The primary efficacy endpoint was change in seated systolic blood pressure (SBP) from baseline. At 12 weeks, mean SBP reduction was 9.2 mmHg in the 20 mg group and 13.7 mmHg in the 40 mg group, compared with 4.1 mmHg in the placebo group. The 40 mg dose achieved a 58 % responder rate (defined as SBP

Phase II/III: Chronic Obstructive Pulmonary Disease

A Phase II/III study enrolled 400 patients with moderate COPD. Participants received either 20 mg bp‑945 or standard care (salmeterol 50 µg twice daily) for 24 weeks. The primary endpoint was improvement in forced expiratory volume in 1 second (FEV1) at 12 hours post‑dose. bp‑945 increased FEV1 by 0.15 L versus 0.22 L with salmeterol (p 

Phase III: Heart Failure with Preserved Ejection Fraction

In the REACH‑HF trial (Randomized Evaluation of bp‑945 in Cardiac Health), 1,500 patients with HFpEF were randomized to bp‑945 30 mg daily or placebo for 52 weeks. The primary composite endpoint of cardiovascular death or heart failure hospitalization was reduced by 21 % in the bp‑945 group (hazard ratio 0.79; 95 % CI 0.66–0.95). Subgroup analysis indicated greater benefit in patients with baseline BNP >400 pg/mL.

Therapeutic Applications

Hypertension

bp‑945’s selective β2‑AR antagonism offers a novel mechanism for lowering arterial pressure through modulation of vascular smooth muscle tone. Clinical data suggest that the drug achieves comparable efficacy to first‑line β‑blockers with fewer β1‑related side effects, such as bradycardia and negative inotropy.

Chronic Obstructive Pulmonary Disease

While β2‑agonists are standard bronchodilators, bp‑945’s antagonistic action at β2‑AR is counterintuitive for COPD. However, evidence indicates that chronic β2‑antagonism may improve airway remodeling and reduce hyperresponsiveness, potentially offering an adjunctive therapeutic strategy for patients with refractory symptoms.

Heart Failure with Preserved Ejection Fraction

The reduction in cardiovascular events in the REACH‑HF trial positions bp‑945 as a promising therapeutic option for HFpEF, a condition with limited pharmacologic interventions. Mechanistic studies suggest that β2‑AR blockade mitigates maladaptive myocardial remodeling and improves diastolic function.

Potential Off‑Target Uses

Preliminary investigations have explored bp‑945’s activity in neurodegenerative diseases. In a mouse model of Parkinson’s disease, oral bp‑945 ameliorated motor deficits by reducing central norepinephrine dysregulation. Further research is needed to evaluate safety and efficacy in humans.

Adverse Effects and Safety Profile

Cardiovascular

In clinical trials, bp‑945 was associated with transient increases in heart rate (max 12 bpm above baseline) and minor decreases in left ventricular ejection fraction (

Respiratory

Because β2‑AR antagonists can theoretically provoke bronchospasm, spirometry monitoring was mandatory. In the COPD trial, only 0.5 % of participants experienced mild bronchospasm, resolved with rescue albuterol. No severe respiratory events were recorded.

Metabolic

Serum glucose and insulin levels remained stable throughout treatment periods. No hypoglycemic episodes were observed in diabetic participants. Liver enzyme elevations were below 1.5 × upper limit of normal and not clinically significant.

Other

Common mild adverse events included headache, dizziness, and nausea. No significant ocular or dermatologic reactions were reported.

Manufacturing and Production

Synthesis

The synthetic route for bp‑945 employs a convergent strategy. The key step is a Buchwald–Hartwig amination of a 4‑trifluoromethyl phenyl bromide with a piperidine derivative, followed by a Suzuki cross‑coupling to introduce the second phenyl ring. Subsequent deprotection and purification steps yield the final product with a purity exceeding 99 % as determined by HPLC.

Scale‑Up and Formulation

Industrial scale synthesis has been optimized for 10,000 kg annual production. The final formulation is a 20 mg oral tablet containing 10 % w/w of bp‑945. The tablet incorporates microcrystalline cellulose and magnesium stearate to ensure consistent dissolution rates. Stability studies demonstrate a shelf life of 36 months under standard storage conditions (25 °C/60 % RH).

Regulatory Status

United States

bp‑945 was granted Fast Track designation by the FDA for the treatment of HFpEF in 2024, following the completion of the REACH‑HF trial. An Investigational New Drug (IND) application was submitted in 2023, and a Phase IV post‑marketing surveillance plan was approved in 2025.

European Union

In 2025, the European Medicines Agency (EMA) granted conditional marketing authorization for bp‑945 under the designation “HeartCare 2.0.” The authorization applies to adults with HFpEF and mild to moderate hypertension. Pharmacovigilance requirements include routine monitoring of cardiovascular outcomes and respiratory adverse events.

Other Jurisdictions

Japan, Canada, and Australia have issued provisional approvals based on Phase III data. Each region requires region‑specific safety monitoring reports, with a particular focus on rare arrhythmic events.

Commercialization and Market Impact

Pricing and Reimbursement

bp‑945 is priced at approximately $125 per monthly supply in the United States, positioning it competitively against existing β‑blockers and diuretics. Insurance coverage varies by payer, with most major plans covering the drug for HFpEF patients under the “heart failure medications” category.

Within two years of launch, bp‑945 captured an estimated 8 % of the β‑blocker market in the United States, primarily among physicians treating HFpEF. In the European market, penetration reached 5 % of the hypertensive drug cohort by 2027.

Branding and Distribution

The product is marketed under the trade name “CardioRelief.” Distribution is managed through a global network of wholesalers, with direct shipment to hospital pharmacies and outpatient clinics. An online patient portal provides dosage instructions and symptom monitoring tools.

Future Directions

Combination Therapy

Preliminary data suggest that bp‑945 may synergize with angiotensin receptor‑neprilysin inhibitors (ARNIs) in HFpEF. A Phase II study exploring the combination of bp‑945 30 mg and sacubitril/valsartan is currently underway.

Biomarker Development

Researchers are investigating plasma β‑adrenergic receptor density as a predictive biomarker for bp‑945 responsiveness. Early-phase studies indicate that patients with higher β2‑AR expression exhibit greater blood pressure reductions.

Expansion to Other Indications

Given the drug’s safety profile, trials are planned to evaluate bp‑945 in atrial fibrillation, where β2‑AR modulation may reduce arrhythmic burden. Additionally, investigation into its potential use in anxiety disorders is ongoing, focusing on its modulatory effects on sympathetic tone.

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