Molecular Basis for Ligand Modulation of a Mammalian Voltage-Gated Ca2+ Channel.

The L-type voltage-gated Ca2+ (Cav) channels are modulated by various compounds exemplified by 1,4-dihydropyridines (DHP), benzothiazepines (BTZ), and phenylalkylamines (PAA), many of which have been used for characterizing channel properties and for treatment of hypertension and other disorders. Here, we report the cryoelectron microscopy (cryo-EM) structures of Cav1.1 in complex with archetypal antagonistic drugs, nifedipine, diltiazem, and verapamil, at resolutions of 2.9 Å, 3.0 Å, and 2.7 Å, respectively, and with a DHP agonist Bay K 8644 at 2.8 Å. Diltiazem and verapamil traverse the central cavity of the pore domain, directly blocking ion permeation. Although nifedipine and Bay K 8644 occupy the same fenestration site at the interface of repeats III and IV, the coordination details support previous functional observations that Bay K 8644 is less favored in the inactivated state. These structures elucidate the modes of action of different Cav ligands and establish a framework for structure-guided drug discovery.

Clinical Outcomes Associated With Diltiazem Use in Heart Failure With Reduced Ejection Fraction After Implementation of a Clinical Support System.

BACKGROUND: Despite atrial fibrillation guideline recommendations, many patients with heart failure with reduced ejection fraction (EF) continue to receive IV diltiazem for acute rate control. OBJECTIVE: Our institution recently implemented a clinical decision support system (CDSS)-based tool that recommends against the use of diltiazem in patients with an EF ≤ 40%. The objective of this study was to evaluate outcomes of adherence to the aforementioned CDSS-based tool. METHODS: This multi-hospital, retrospective study assessed patients who triggered the CDSS alert and compared those who did and did not discontinue diltiazem. The primary outcome was the occurrence of clinical deterioration. The primary endpoint was compared utilizing a Fisher's Exact Test, and a multivariate logistic regression model was developed to confirm the results of the primary analysis. RESULTS: A total of 246 patients were included in this study with 146 patients in the nonadherent group (received diltiazem) and 100 patients in the adherent group (did not receive diltiazem). There was a higher proportion of patients experiencing clinical deterioration in the alert nonadherence group (33% vs 21%, P = 0.044), including increased utilization of inotropes and vasopressors, and higher rate of transfer to ICU. CONCLUSION AND RELEVANCE: In patients with heart failure with reduced EF, diltiazem use after nonadherence to a CDSS alert resulted in an increased risk of clinical deterioration. This study highlights the need for improved provider adherence to diltiazem clinical decision support systems.

Comparative safety and efficacy of a hybrid intravenous and oral diltiazem protocol for acute rate control in the emergency department.

STUDY OBJECTIVE: Intravenous diltiazem has experienced numerous supply shortages over the past few years. The purpose of this study was to compare the safety and efficacy of a traditional diltiazem intravenous bolus and continuous infusion protocol to a diltiazem intravenous bolus and oral maintenance protocol for acute rate control in the emergency department. METHODS: Patients who received intravenous diltiazem in the emergency department between January 1, 2018 and May 31, 2019 were screened. Patients were included if they received the diltiazem intravenous bolus and continuous infusion protocol (IV + infusion group) or the hybrid diltiazem intravenous bolus and oral maintenance protocol (IV + PO group). The primary outcome was the proportion of patients with rate control, without need for additional rate control agents or additional boluses during the maintenance phase. RESULTS: A total of 106 patients were matched with 53 patients in each group. For the primary outcome of rate control at four hours, 62.3% of patients in the intravenous bolus + infusion group versus 75.5% of patients in the IV bolus + PO group (p = 0.142) achieved rate control. There was no difference in rates of hypotension or bradycardia between groups. CONCLUSION: Results of this study demonstrated no difference in acute rate control when using a hybrid IV and oral diltiazem protocol, compared to a traditional IV bolus and infusion strategy. This information supports the further use of a hybrid diltiazem IV and oral protocol, which provides increased flexibility during shortages of either medication.

Utility of native emission quenching of erythrosine B for the determination of diltiazem in different dosage forms.

This study introduces a practical and cost-effective method for tracking diltiazem (DLZ) analytically. It utilizes a fluorimetric approach that relies on the modulation of fluorescence intensity of a dye called erythrosine B. Through a one-pot experiment performed in an acidic environment, a complex is rapidly formed between DLZ and erythrosine B. By observing the decrease in erythrosine B emission, a linear calibration plot is established, enabling the detection and quantification of DLZ concentrations ranging from 40 to 850 ng/ml. The estimated limits of detection and quantitation were 10.5 and 32.1 ng/ml, respectively. The variables affecting the DLZ-dye complex system were carefully adjusted. The validity of the approach was confirmed through a thorough evaluation based on the criteria set by ICH guidelines. The accuracy and precision of the methodology were evaluated, and the standard deviation and relative standard deviation were below 2. The strategy was successfully employed to analyze DLZ in tablets and capsules, and no significant variation between the proposed and reported methods as the values of the estimated t-test and F-test at five determinations were below 2.306 and 6.338, respectively. Notably, the method adheres to the principle of green chemistry by utilizing distilled water as the dispersing medium.

Safety of Diltiazem for Acute Management of Atrial Fibrillation (AF) in Patients with Heart Failure and Reduced Ejection Fraction in the Emergency Department.

BACKGROUND: Diltiazem is an effective rate control agent for atrial fibrillation with rapid ventricular rate (AF RVR). However, its negative inotropic effects may increase the risk for worsening heart failure in patients with a reduced ejection fraction (EF). OBJECTIVES: This observational study aims to describe the incidence of worsening heart failure in patients who receive intravenous diltiazem for acute atrial fibrillation management. METHODS: Adult patients that received diltiazem in the emergency department (ED) for AF RVR (heart rate ≥ 100 beats/min) from 2021 to 2022 and had a prior documented EF were included. The primary outcome is worsening heart failure within 24 h of diltiazem administration. Secondary outcomes include return ED visits and death within 7 days. EF percentage was compared across outcomes using Wilcoxon rank-sum tests. Outcomes were compared by reduced EF (< 50%) and preserved EF (≥ 50%). Continuous data were summarized with medians and interquartile ranges, and categorical features were summarized with frequency counts and percentages. Wilcoxon rank-sum tests were used for numeric outcomes and chi-squared tests or Fisher's exact tests for categorical outcomes, with a p-value < 0.05 considered statistically significant. RESULTS: There were 674 patients with AF RVR that received diltiazem, and 386 patients met the inclusion criteria for analysis. Baseline demographics included a median age of 72 (64-81) years, with 14.5% of patients having a prior diagnosis of congestive heart failure. EF < 50% was identified in 13.7% of patients (n = 53), of which approximately 30% of these patients safely discharged home after receiving i.v. diltiazem. The primary outcome of worsening heart failure occurred in 7/41 (17%) and 10/207 (4.8%) patients with reduced and preserved ejection fractions, respectively, who were admitted to the hospital (p = 0.005). CONCLUSION: The development of worsening heart failure is multifactorial and may include the use of diltiazem in critically ill patients requiring hospital admission.

Impact of intravenous calcium with diltiazem for atrial fibrillation/flutter in the emergency department.

OBJECTIVE: The purpose of this study was to evaluate the effect of early intravenous (IV) calcium on systolic blood pressure (SBP) when administered with IV diltiazem in subjects with atrial fibrillation (AF) or flutter (AFL) with rapid ventricular response (RVR) in the Emergency Department (ED). METHODS: This was a multicenter, retrospective cohort study that evaluated adults admitted to the ED with documented AF or AFL, heart rate (HR) > 120 bpm, SBP 90 to 140 mmHg, and received treatment with IV diltiazem for rate control. The primary outcome was the change in SBP 60 min (+/- 30 min) after initial IV diltiazem administration. Secondary outcomes included time to initial rate control (HR < 100 bpm), time to sustained rate control (HR < 100 bpm for 3 h), change in HR, rates of hypotension, bradycardia, hypercalcemia, and line extravasation within 24 h of initial diltiazem administration. RESULTS: There were 198 subjects in the diltiazem monotherapy group and 56 subjects in the diltiazem with calcium group meeting the inclusion criteria. The primary outcome, median change in SBP 60 min after initial IV diltiazem administration, was similar between groups (-2 mmHg vs -1.5 mmHg; p = 0.642), but this difference was not statistically significant. All secondary outcomes were found to be similar between groups. Although not statistically significant, hypotension occurred more often in the diltiazem with calcium group (20.2% vs 32.1%; p = 0.060) while bradycardia occurred more often in the diltiazem monotherapy group (4.5% vs 0%; p = 0.213). In terms of achieving rate control, the administration of calcium with diltiazem did not significantly change the time to initial rate control (1.4 h vs 1.8 h; p = 0.141) or time to sustained rate control (7.9 h vs 7.7 h; p = 0.570) compared to diltiazem alone. CONCLUSIONS: In the setting of AF/AFL with RVR, administration of IV calcium with IV diltiazem did not show a significant impact on clinical or safety outcomes compared to IV diltiazem monotherapy.

The effect of serum calcium level on the success of diltiazem treatment: A retrospective cohort study.

INTRODUCTION: Diltiazem is an antiarrhythmic drug widely used in the treatment of atrial fibrillation (AFib) with rapid ventricular response (RVR). It reveals its effect by blocking L-type calcium channels. Thus, it inhibits the extracellular calcium influx into the cytosol. The relationship between serum calcium level and the efficacy of intravenous (IV) diltiazem used in the treatment of AFib with RVR has not been investigated in vivo. The aim of this study is to investigate the mentioned relationship. METHODS: This study was planned as a single-center retrospective study. The data of 349 patients who presented to the emergency department with AFib with RVR and treated with diltiazem were retrospectively analyzed. A patient was considered to have responded to diltiazem treatment if the existing heart rhythm returned to sinus rhythm, or the heart rate decreased below 100 beats/min, or the heart rate decreased >20% provided that it was below 120 beats/min. The ionized calcium levels were recorded. The relationship between serum calcium level and the success of diltiazem treatment was examined. RESULTS: Fifty five percent of the patients were female. The median age was 75 years. The rate of response to diltiazem treatment was 67.3%. The median of ionized calcium levels in the group which responded to diltiazem treatment (n = 235) was 1.14 mmol/L (IQR: 0.12), and the group which did not respond to diltiazem treatment (n = 114) was 1.11 mmol/L (IQR: 0.12) (p = 0.322). The patients were divided into three groups as low, normal, and high calcium levels according to the calcium reference levels determined by the hospital laboratory. The rate of response to diltiazem treatment was 61.4% in patients with low ionized calcium levels, 76.1% in patients with normal ionized calcium levels, and 40.0% in patients with high ionized calcium levels. The rate of response to diltiazem treatment was higher in patients with normal ionized calcium levels compared to patients with low or high ionized calcium levels (p = 0.004, p = 0.003). CONCLUSION: The success rate of diltiazem used in the treatment of AFib with RVR was highest in physiological calcium levels. The current study may provide the clinician with awareness about the consideration of serum ionized calcium levels when choosing drugs in patients with AFib with RVR.

Procainamide-Provoked Brugada Pattern in a Patient Presenting with New-Onset Atrial Fibrillation or Flutter: When Does it Matter?

BACKGROUND: Brugada syndrome (BrS) is an inherited disease that can lead to sudden cardiac death. Medications, such as antidysrhythmics, and fevers can unmask or induce the Brugada pattern on an electrocardiogram (ECG). This case report highlights a patient who developed drug-induced Brugada type I pattern after a procainamide infusion for the treatment of new-onset atrial fibrillation (AF) or flutter and discusses the implications for this incidental but potentially lethal finding. CASE REPORT: We report a case of a young man who presented to the emergency department (ED) with new-onset AF with rapid ventricular response that began within 12 h of presentation. ED treatments included a crystalloid IV fluid bolus, diltiazem pushes, synchronized electrical cardioversion, and a procainamide infusion. After the procainamide infusion, the patient developed ECG findings consistent with Brugada pattern. Both the AF and Brugada pattern resolved spontaneously within 24 h. The patient was discharged without implantable cardioverter defibrillator placement due to presumed isolated procainamide-induced Brugada pattern and lack of concerning features, such as inducible dysrhythmia during electrophysiology study, family history of sudden death, and history of syncope. The patient was counseled to follow-up with genetics and avoid BrS-inducing medications. WHY SHOULD AN EMERGENCY PHYSICIANS BE AWARE OF THIS?: Procainamide, an option for the treatment of AF in the ED, can provoke Brugada pattern. If encountered, it is important to recall that some patients may not be diagnosed with BrS if determined to be low risk according to the Shanghai criteria. All patients should be referred to cardiology for further evaluation.

In Esophageal Squamous Cells From Eosinophilic Esophagitis Patients, Th2 Cytokines Increase Eotaxin-3 Secretion Through Effects on Intracellular Calcium and a Non-Gastric Proton Pump.

BACKGROUND & AIMS: In upper airway cells, T helper 2 cytokines that signal through interleukin-4 (IL-4) receptor-α have been shown to stimulate eotaxin-3 secretion via a nongastric proton pump (ngH+,K+ATPase). To seek novel targets for eosinophilic esophagitis (EoE) treatments, we evaluated ngH+,K+ATPase expression in EoE squamous cells, and explored molecular pathways involved in eotaxin-3 secretion by IL-4 receptor-α signaling. METHODS: ngH+,K+ATPase expression in EoE cells was evaluated by quantitative real-time polymerase chain reaction and Western blotting. IL-4-stimulated eotaxin-3 secretion was measured by enzyme-linked immunosorbent assay after treatment with omeprazole, SCH 28080 (potassium-competitive acid blocker), ethylene glycol-bis(ß-aminoethyl)-N,N,N',N'-tetraacetoxymethyl ester (calcium chelator), 2-aminoethoxydiphenyl borate (inhibitor of endoplasmic reticulum calcium release), verapamil, and diltiazem (L-type calcium channel inhibitors). Intracellular calcium transients were measured by Fluo-4 fluorescence. Key experiments were confirmed in EoE primary cells and in RNA sequencing datasets from mucosal biopsies of patients with EoE and controls. RESULTS: EoE cells expressed ngH+,K+ATPase messenger RNA and protein. Omeprazole and SCH 28080 decreased IL-4-stimulated eotaxin-3 secretion. IL-4 increased intracellular calcium transients, and IL-4-stimulated eotaxin-3 secretion was blocked by ethylene glycol-bis(ß-aminoethyl)-N,N,N',N'-tetraacetoxymethyl ester, 2-aminoethoxydiphenyl borate, verapamil, and diltiazem. The combination of omeprazole and verapamil suppressed IL-4-stimulated eotaxin-3 secretion more than either agent alone. EoE biopsies expressed higher ngH+,K+ATPase and exhibited more calcium signaling than controls. CONCLUSIONS: EoE cells express a nongastric proton pump that mediates T helper 2 cytokine-stimulated eotaxin-3 secretion. IL-4 induces calcium release from the endoplasmic reticulum and calcium entry via L-type calcium channels, increasing intracellular calcium that contributes to eotaxin-3 secretion by EoE cells. L-type calcium channel inhibitors block T helper 2 cytokine-stimulated eotaxin-3 secretion, suggesting a potential role for these agents in EoE treatment.

A systematic review and meta-analysis of the efficacy of topical sphincterotomy treatments for anal fissure.

BACKGROUND: Anal fissure is a common condition that can be treated medically or surgically. Chemical sphincterotomy is often used before surgical intervention. This study aims to evaluate the effectiveness of topical agents for chemical sphincterotomy on healing of anal fissures and side-effects. METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) compliant systematic review was performed using MEDLINE, EMBASE, Scopus, and CENTRAL databases. Eligible studies included randomized controlled trials which compared topical sphincterotomy agents with topical placebo agents or each other. Studies that included surgical treatments were excluded. Overall evidence was synthesized according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. RESULTS: Thirty-seven studies met the study selection criteria. Seventeen studies show that glyceryl trinitrate (GTN) was significantly more likely to heal anal fissure than placebo (relative risk (RR) = 1.96, 95% confidence interval (95%CI) = 1.35-2.84, I2 = 80%). Eleven studies showed a marginally significant difference between healing rates for diltiazem vs GTN, RR = 1.16, (1.01-1.33) I2 = 48%. There was no significant difference in healing between diltiazem and placebo, RR = 1.65, (0.64-4.23), I2 = 92%. GTN significantly reduced pain on the visual analog scale compared to the placebo group, MD-0.97 (-1.64 to -0.29) I2 = 92%. There was high certainty of evidence that GTN was significantly more likely to cause headache than placebo (RR = 2.73 (1.82-4.10) I2 = 58%) and diltiazem RR = 6.88 (2.19-21.63) I2 = 17%. CONCLUSION: There is low certainty evidence topical nitrates are an effective treatment for anal fissure healing and pain reduction compared to placebo. Despite widespread use of topical diltiazem, more evidence is required to establish the effectiveness of calcium channel blockers compared to placebo.

In vitro and in vivo impacts of nifedipine and diltiazem on praziquantel chemotherapy in murine Schistosoma mansoni.

AIM: This study was planned to evaluate the in vitro and in vivo antischistosomal effects of the widely used antihypertensive drugs, nifedipine (NIF) and diltiazem (DTZ), and their combinations with praziquantel (PZQ) on early and late Schistosoma (S.) mansoni infections 21- and 45- days old stages. METHODS: In the In vitro study, Calcium channel blockers (CCBs), NIF and DTZ were added to schistosomula and adult worm cultures in different concentrations 10, 20 and 30 mg/ml. The mortality percentage was calculated 1, 12 and 24 h after incubation. In vivo, NIF and DTZ either alone or combined with PZQ were used to treat male albino mice. The parasitological and total immunoglobulin (Ig) G and IgM anti-soluble egg antigen (SEA) were assessed to demonstrate the disease severity. RESULTS: In the In vitro study, 10 mg/ml NIF induced 100% mortality percentage of both schistosomula and adult worms after 24 h incubation, while DTZ induced similar mortality percentage at 30 mg/ml concentration. In vivo results showed that early or late combination of 30 mg/kg of NIF, but not DTZ, significantly (P <0.05) enhanced the reductive efficacy of PZQ based on the parasitological data. The maximal reduction (P <0.05) of anti-SEA IgM and IgG levels was developed during NIF-PZQ administration 21- (1.12 ± 0.06 and 1.09 ± 0.04, respectively) or 45- (1.00 ± 0.03 and 0.8 ± 0.06, respectively) days post infection (PI), compared to either PZQ or NIF individual treatments. The decreased concentration of anti-SEA antibodies was correlated with the diminished granulomatous diameter and disease severity. CONCLUSION: Nifedipine improved PZQ chemotherapy targeting either early or late S. mansoni infection in mice compared to the PZQ mono-therapy. Administering NIF can be considered as a promising drug candidate for schistosomiasis chemotherapy.

Intravenous diltiazem versus metoprolol for atrial fibrillation with rapid ventricular rate: A meta-analysis.

BACKGROUND: Intravenous diltiazem and metoprolol are both commonly used to treat atrial fibrillation (AF) with rapid ventricular rate (RVR) in the emergency department (ED), but the advantages and disadvantages of these drugs cannot be verified. This meta-analysis aimed to assess the efficacy and safety of intravenous diltiazem versus metoprolol for AF with RVR. METHOD: We systematically searched PubMed, Web of Science, Embase, Cochrane library, the China National Knowledge Infrastructure (CNKI), Wanfang, China Biology Medicine disc (CBM) and the WeiPu (VIP). Meta-analysis was performed using weighted mean difference (WMD), relative risk (RR) and 95% confidence interval (CI). Statistical analysis was performed using Review Manager 5.4.1. RESULTS: Seventeen studies involving 1214 patients in nine randomized controlled trials (RCTs) and eight cohort studies were included in meta-analysis, including 643 patients in the intravenous diltiazem group and 571 patients group in the intravenous metoprolol. The results of the meta-analysis showed that compared with intravenous metoprolol, intravenous diltiazem was found higher efficacy (RR =1.11; 95% CI = 1.06 to 1.16, p < 0.00001), shorter average onset time (RR = -1.13; 95% CI = -1.97 to -0.28, p = 0.009), lower ventricular rate (RR = -9.48; 95% CI = -12.13 to -6.82, p<0.00001), less impact on systolic blood pressure (WMD = 3.76; 95% CI: 0.20 to 7.33, P = 0.04), and no significant difference in adverse events (RR = 0.80, 95% CI = 0.55 to 1.14, P = 0.22) and diastolic blood pressure (WMD = -1.20; 95% CI: -3.43 to 1.04, P = 0.29) was found between intravenous diltiazem and metoprolol. CONCLUSION: Intravenous diltiazem has higher efficacy, shorter average onset time, lower ventricular rate, less impact on blood pressure, and with no increase in adverse events compared to intravenous metoprolol.

Acute management of atrial fibrillation in congestive heart failure with reduced ejection fraction in the emergency department.

INTRODUCTION: Acute heart rate control for atrial fibrillation (AF) with rapid ventricular response (RVR) in the emergency department (ED) is often achieved utilizing intravenous (IV) non-dihydropyridine calcium channel blockers (CCB) or beta blockers (BB). For patients with concomitant heart failure with a reduced ejection fraction (HFrEF), the American Heart Association and other clinical groups note that CCB should be avoided due to their potential negative inotropic effects. However, minimal evidence exists to guide this current recommendation. The primary objective of this study was to compare the incidence of adverse effects in the HFrEF patient population whose AF with RVR was treated with IV diltiazem or metoprolol in the ED. METHODS: This single center, retrospective review included patients ≥18 years old with HFrEF who presented in AF with RVR and received IV diltiazem or metoprolol in the ED. The primary outcome was adverse effects of therapy defined as: 1) hypotension (systolic blood pressure < 90 mmHg requiring fluid bolus or vasopressors) or bradycardia (heart rate < 60 beats/min) within 60 min of medication administration 2) worsening heart failure symptoms defined as increased oxygen requirements within four hours or inotropic support within 48 h. Secondary outcomes included the incidence of rate control failure, patient disposition, ED length of stay, hospital length of stay, and in-hospital mortality. RESULTS: One hundred and twenty-five patients met inclusion criteria, with 57 receiving diltiazem and 68 receiving metoprolol. Overall adverse effects for diltiazem and metoprolol were similar (32% vs. 21%, P = 0.217). However, there was a significantly higher incidence of worsening heart failure symptoms within the diltiazem group (33% vs 15%, P = 0.019). Rate control failure at 60 min did not differ significantly between diltiazem and metoprolol (51% vs 62%, P = 0.277). CONCLUSIONS: In HFrEF patients with AF, there was no difference in total adverse events in patients treated with IV diltiazem compared to metoprolol. However, the diltiazem group had a higher incidence of worsening CHF symptoms defined as increased oxygen requirement within four hours or initiation of inotropic support within 48 h.

Intravenous metoprolol versus diltiazem for atrial fibrillation with concomitant heart failure.

PURPOSE: Atrial fibrillation (Afib) with rapid ventricular response (RVR) is acutely treated with intravenous push (IVP) metoprolol (MET) or diltiazem (DIL). In heart failure (HF) patients, diltiazem is not recommended due to negative inotropic effects. Studies comparing the treatment of atrial fibrillation often exclude HF. Hirschy et al. evaluated HF patients with concomitant Afib with RVR who received IVP metoprolol or diltiazem to determine their effectiveness and safety. They found similar safety and effectiveness outcomes between the two groups. METHODS: This retrospective, IRB-approved study evaluated patients presenting to the emergency center (EC) with Afib with RVR and HF from January 1, 2018 to July 31, 2021. Included patients were 18 years of age or older, received IVP metoprolol or diltiazem in the EC, and had a recorded baseline ejection fraction (EF). The primary effectiveness outcome was successful heart rate (HR) control 30 min after treatment with either IVP metoprolol or diltiazem, which was defined as HR <100 beats per minute (bpm). Secondary effectiveness outcomes included HR control 60 min post-IVP and at EC discharge or transfer and HR reduction >20% at 30 min after IVP, 60 min after IVP, and at time of discharge or transfer. Other secondary outcomes included the time to adequate HR control, the total dose of IVP metoprolol or diltiazem given, any additional rate-controlling agents given, and crossover between metoprolol and diltiazem. Safety outcomes included bradycardia, hypotension, shortness of breath, increased oxygen requirements, change in EF, acute kidney injury or renal replacement therapy. RESULTS: Of 2580 evaluated, 193 patients were included (134 DIL vs. 59 MET) with age 73.3 ± 12.2 years, 63% female. The average EF was 48.2 ± 14.2% and 30% of patients had heart failure with reduced ejection fraction (HFrEF) while 64% had heart failure with preserved ejection fraction (HFpEF). Effective heart rate control 30 min post-IVP was not different between the two groups (55% DIL vs. 41% MET, p = 0.063). DIL effectively controlled HR quicker than MET (13 [9, 125] DIL vs. 27 [5, 50] MET, min, p = 0.009). DIL resulted in greater HR reductions at 30 min (33.2 ± 25.4 DIL vs. 19.7 ± 19.7 MET, bpm, p < 0.001) and at 60 min (31 ± 23.5 DIL vs. 19.6 ± 19.1 MET, bpm, p = 0.002). DIL also more frequently resulted in a HR reduction of 20% or greater at 30 min (63% DIL vs. 27% MET, p < 0.001), 60 min post-IVP (59% DIL vs. 41% MET, p = 0.019), and at time of patient discharge or transfer from the EC (70% DIL vs. 49% MET, p = 0.005). No differences in safety outcomes were identified. CONCLUSION: Acute management of patients with Afib with RVR and HF is challenging. While successful rate control at 30 min was not significantly different between diltiazem and metoprolol, IVP diltiazem reduced HR more quickly and reduced HR by 20% or greater more frequently than IVP metoprolol with no safety outcome differences. Further studies are needed to evaluate diltiazem's safety in patients with Afib and HF.

Assessment of Anti-Xa activity in patients receiving concomitant apixaban with strong p-glycoprotein inhibitors and statins.

WHAT IS KNOWN AND OBJECTIVES: Although the apixaban Food and Drug Administration (FDA) package insert recommends dose reduction in patients administered dual strong inhibitors of p-glycoprotein (P-gp) and cytochrome P-450 (CYP) 3A4, there are limited published data regarding potential drug-drug interactions between apixaban (Eliquis) and common p-glycoprotein (P-gp) and CYP3A4 inhibitors co-administered with statins. The aim of this study was to investigate the degree of elevation relative to apixaban serum peak and trough concentration after the co-administration of amiodarone, diltiazem and statins (atorvastatin, rosuvastatin and simvastatin). METHODS: Patients prescribed apixaban 5mg twice daily for at least one week were identified from the anticoagulation clinic database and contacted for potential enrolment. A total of 117 volunteers were enrolled with eight excluded due to discontinued use, resulting in 109 volunteers (44 females and 65 males delineated into age groups 40-64 and ≥65 years old) completing the observational study. Fifty-five volunteers were administered apixaban without the P-gp inhibitors amiodarone or diltiazem, with or without statins (atorvastatin, rosuvastatin and simvastatin). Fifty-four volunteers were administered apixaban with either amiodarone or diltiazem, with or without statins (atorvastatin, rosuvastatin or simvastatin). Peak and trough concentrations were assessed for each patient utilizing an apixaban anti-Xa assay. RESULTS: Of the combinations studied, the mean apixaban trough concentration upon co-administration of amiodarone without a statin was elevated compared to apixaban alone (experimental 156.83 +/- 79.59 ng/ml vs. control 104.09 +/- 44.56 ng/ml; p = 0.04). The co-administration of diltiazem and rosuvastatin, and the administration of amiodarone without a statin led to greater than 1.5-fold increase in apixaban concentrations (peak experimental 315.19 +/- 157.53 ng/ml vs control 207.6 +/- 83.38 ng/ml; p = 0.08 and trough experimental 182.03 +/- 95.93 ng/ml vs control 112.32 +/- 37.78 ng/ml; p = 0.17) suggesting the need to assess dose adjustment for patients per the FDA package insert. In addition, the aggregated mean peak (p = 0.0056) and trough (p = 0.0089) elevation of CYP3A4 experimental groups (atorvastatin and simvastatin) co-administered apixaban and diltiazem were statistically significant compared with the aggregated non-CYP3A4 control groups (no statin and rosuvastatin). WHAT IS NEW AND CONCLUSION: Herein, we report novel data regarding peak and trough apixaban concentrations after concomitant administration of P-gp and CYP3A4 inhibitors (amiodarone or diltiazem) co-administered with statins (atorvastatin, rosuvastatin or simvastatin). Providers should consider utilizing the apixaban anti-Xa assay or comparative heparin anti-Xa assay to determine if patients require dose reduction to decrease adverse events in high-risk patients prescribed apixaban and concomitant p-glycoprotein and CYP3A4 inhibitors amiodarone or diltiazem with and without a CYP3A4 or non-3A4 statin.

Results of patch testing in acute generalized exanthematous pustulosis (AGEP): A literature review.

The literature on positive patch-test results in acute generalized exanthematous pustulosis (AGEP) is reviewed. Ninety-three drugs were identified that have together caused 259 positive patch tests in 248 patients with AGEP. The drug classes causing the highest number of reactions are beta-lactam antibiotics (25.9%), other antibiotics (20.8%), iodinated contrast media (7.3%), and corticosteroids (5.4%), together accounting for nearly 60% of all reactions. The highest number of reactions to individual drugs was to amoxicillin (n = 36), followed by pristinamycin (n = 25), diltiazem (n = 14), amoxicillin-clavulanic acid (n = 13), clindamycin (n = 11), and iomeprol (n = 8); 59 of the 93 drugs each caused a single case only. The "Top-10" drugs together caused over 50% of all reactions. The sensitivity of patch testing (percentage of positive reactions) in patients with AGEP is largely unknown, but may generally be ~50%, which also applies to pristinamycin. Patch testing in AGEP appears to be safe, although mild recurrence of AGEP skin symptoms or other rashes may occur occasionally. Clinical aspects of AGEP, including epidemiology, etiology and pathophysiology, clinical features, histology, treatment, and prognosis are briefly presented, as are diagnosing the disease and identifying the culprit drugs with patch tests, intradermal tests, in vitro tests, and challenge tests.

Enthalpy-Entropy Compensation in the Structure-Dependent Effect of Nonsteroidal Anti-inflammatory Drugs on the Aqueous Solubility of Diltiazem.

Certain combinations of acidic and basic drugs can cause significant changes in physicochemical properties through the formation of ionic liquids, eutectic mixtures, or deep eutectic solvents. In particular, combining indomethacin and lidocaine is known to result in apparent increases in both the partition coefficients (hydrophobicity) and aqueous solubilities (hydrophilicity). The physicochemical interactions between drugs change the water solubility of the drugs and affect the bio-availability of active pharmaceutical ingredients. Therefore, we need to clarify the mechanism of changes of water solubility of drugs through the physicochemical interactions. In the present study, we identified a thermodynamic factor that regulates the dissolution of a basic drug, in the presence of various acidic nonsteroidal anti-inflammatory drugs. The results demonstrated that enthalpy-entropy compensation plays a key role in the dissolution of drug mixtures and that relevant thermodynamic conditions should be considered.

Convolution- and Deconvolution-Based Approaches for Prediction of Pharmacokinetic Parameters of Diltiazem Extended-Release Products in Flow-Through Cell Dissolution Tester.

The present study evaluated the effect of different configuration setups of the Flow-Through Cell (USP IV) dissolution tester in developing in vitro-in vivo correlation (IVIVC). A Biopharmaceutics Classification System (BCS) Class I Diltiazem (DTZ), formulated in extended-release (ER) gel-matrix system, was employed for this purpose. The study also assessed the validity and predictability of IVIVC employing both deconvolution- and convolution-based approaches. In vitro release was conducted in USP IV as open- or closed-loop setups, while the pharmacokinetic (PK) data were obtained from a previous fasted-state cross-over study conducted on 8 healthy male volunteers, after oral administration of ER matrix tablets against market product (Tildiem Retard® 90 mg). PK parameters (Cmax, AUC0-t and AUC0-∞) were predicted, and compared with actual data to establish the strength of correlation models. Results showed that DTZ release from ER products was influenced by operating the FTC in different configuration-setups, where ≥ 75% of labeled DTZ was released after 6 h and 12 h using the open- and closed-loop settings, respectively. Correlation between fraction-dissolved versus fraction-absorbed for both ER products displayed linear relation upon employing FTC open-loop setup. Convolution-based approach was more discriminative in predicting DTZ in vivo PK parameters with a minimal prediction error, compared to deconvolution-based approach. A successful trial to predict DTZ PKs from individual in vitro data performed in USP IV dissolution model was established, employing convolution technique. Basic principle of the convolution approach provides a simple and practical method for developing IVIVC, hence could be utilized for other BCS Class I extended-release drug products.

Diltiazem on tacrolimus exposure and dose sparing in Chinese pediatric primary nephrotic syndrome: impact of CYP3A4, CYP3A5, ABCB1, and SLCO1B3 polymorphisms.

PURPOSE: To evaluate the role of diltiazem on tacrolimus sparing in pediatric primary nephrotic syndrome (PNS) and its relation to CYP3A4, CYP3A5, ABCB1, and SLCO1B3 polymorphisms. METHODS: The PNS children treated with tacrolimus and with steady-state trough concentration (C0) were retrospectively collected. The impacts of diltiazem on tacrolimus dose-adjusted C0 (C0/D), target concentration achievement, and required dose were evaluated. Meanwhile, the relationship between the polymorphisms (including CYP3A4*1G, CYP3A5*3, ABCB1-C3435T, and SCLO1B3) and dose-sparing effect were investigated. RESULTS: A total of 71 children with 535 concentrations, including 16 children with concomitant diltiazem, were involved. Significantly increased C0/D (94.0 vs 83.8 ng/mL per mg/kg, p = 0.038) and lower required daily dose of tacrolimus (0.056 vs 0.064 mg/kg, p = 0.003) were observed in patients co-administered with diltiazem. Subpopulation carrying CYP3A4*1G, CYP3A5*1, ABCB1-3435TT, or SLCO1B3-699AA was presented with enhanced increment in tacrolimus C0/D by 38.8-102.9%. CONCLUSION: Moderate effect of diltiazem on tacrolimus sparing, which might relate to the polymorphisms of CYP3A4, CYP3A5, ABCB1, and SLCO1B3, was documented.

Comparison of sustained rate control in atrial fibrillation with rapid ventricular rate: Metoprolol vs. Diltiazem.

OBJECTIVE: The objective of this study was to compare sustained rate control with intravenous (IV) diltiazem vs. IV metoprolol in acute treatment of atrial fibrillation (AF) with rapid ventricular rate (RVR) in the emergency department (ED). METHODS: This retrospective chart review at a large, academic medical center identified patients with AF with RVR diagnosis who received IV diltiazem or IV metoprolol in the ED. The primary outcome was sustained rate control defined as heart rate (HR) < 100 beats per minute without need for rescue IV medication for 3 h following initial rate control attainment. Secondary outcomes included time to initial rate control, HR at initial control and 3 h, time to oral dose, admission rates, and safety outcomes. RESULTS: Between January 1, 2016 and November 1, 2018, 51 patients met inclusion criteria (diltiazem n = 32, metoprolol n = 19). No difference in sustained rate control was found (diltiazem 87.5% vs. metoprolol 78.9%, p = 0.45). Time to rate control was significantly shorter with diltiazem compared to metoprolol (15 min vs. 30 min, respectively, p = 0.04). Neither hypotension nor bradycardia were significantly different between groups. CONCLUSIONS: Choice of rate control agent for acute management of AF with RVR did not significantly influence sustained rate control success. Safety outcomes did not differ between treatment groups.