Formulations Of Nifedipine Research Articles

Fabrication, evaluation, and enhanced penetration of vinyl and cellulose-engineered transdermal patch of nifedipine using essential oil as penetration enhancer

The aim of this study was to develop and evaluate the transdermal patch formulations of nifedipine. The patch formulations containing nifedipine were prepared and optimized with different ratios of vinyl and cellulose-derived polymers, drug contents, and permeation enhancers. Among the various formulations, the patch formulation containing a 1:5 ratio of ethyl cellulose and polyvinyl pyrrolidone was selected for ex vivo pharmacokinetic study based on in vitro permeation studies using stratum corneum of the pig’s skin. The cumulative percentage release after the transdermal administration of the optimized patch formulation was 71.43%, and the plasma concentration of nifedipine was maintained for 16 hrs. The physicochemical evaluation study including flatness, thickness, moisture content and uptake, drug content in vitro release, and ex vivo permeation indicated satisfactory results. The formulation batch with clove oil as a penetration enhancer has shown better ex vivo permeation as compared to the formulations without enhancers and another synthetic enhancer. These results suggest that the optimized patch formulation Q3 could be further developed for clinical applications, providing the therapeutic plasma level of nifedipine over an extended period. Hence analyzing the results of the evaluation tests, in vitro and ex vivo data on the preparation and optimization of nifedipine-loaded transdermal patch, it can be concluded that the formulation shows its feasibility as an effective transdermal delivery system for nifedipine.

Seasonal variation in ambulatory blood pressure control in patients on clinic blood pressure-guided antihypertensive treatment.

We investigated seasonal variation in ambulatory blood pressure control in hypertensive patients on clinic blood pressure-guided antihypertensive treatment. The study participants were hypertensive patients enrolled in an 8-week therapeutic study. Antihypertensive treatment was initiated with long-acting dihydropyridine calcium channel blockers amlodipine 5 mg/day or the gastrointestinal therapeutic system (GITS) formulation of nifedipine 30 mg/day, with the possible up-titration to amlodipine 10 mg/day or nifedipine-GITS 60 mg/day at 4 weeks of follow-up. The proportion of up-titration to higher dosages of antihypertensive drugs at 4 weeks of follow-up was higher in patients who commenced treatment in autumn/winter ( n = 302) than those who commenced treatment in spring/summer ( n = 199, 24.5 vs. 12.0%, P < 0.001). The control rate of clinic blood pressure, however, was lower in autumn/winter than in spring/summer at 4 (56.7 vs. 70.7%, P = 0.003) and 8 weeks of follow-up (52.5 vs. 74.9%, P < 0.001). At 8 weeks, patients who commenced treatment in autumn/winter, compared with those who commenced treatment in spring/summer, had a significantly ( P ≤0.03) smaller daytime (mean between-season difference -3.2/-2.8 mmHg) but greater nighttime SBP/DBP reduction (3.6/1.6 mmHg). Accordingly, at 8 weeks, the prevalence of nondippers was significantly ( P < 0.001) higher in spring/summer than in autumn/winter for both SBP (54.8 vs. 30.0%) and DBP (53.4 vs. 28.8%). Clinic blood pressure-guided antihypertensive treatment requires a higher dosage of medication in cold than warm seasons, which may have led to over- and under-treatment of nighttime blood pressure, respectively.

Late-onset non-obstructive mesenteric ischemia (NOMI) resulting from delayed absorption of overdosed antihypertensive drugs: An autopsy case report.

Non-obstructive mesenteric ischemia (NOMI) is caused by reduced blood flow to the intestines without physical occlusion in the mesenteric artery. Previous reports show that drug overdose occasionally induces late-onset NOMI; however, in most cases, the reason for the delayed onset is unclear. Here, we present an autopsy case of late-onset NOMI that was induced by a drug overdose. An 80-year-old man was admitted to the intensive care unit because of severe hypotension after an overdose of antihypertensive drugs. He received vasopressor therapy and continuous hemodiafiltration dialysis; however, gastrointestinal decontamination was not performed. He began to recover but developed acute mesenteric ischemia on the evening of day 4 and died on day 5. Autopsy showed discontinuous submucosal bleeding from the duodenum to the colon; there was no thrombus in the mesenteric artery, which led to a diagnosis of NOMI. In the stomach, there was 250mL of reddish-brown fluid with a muddy brown substance. Histologic examination revealed ischemic necrosis in the small intestine. Quantitative analysis of serum collected during hospitalization revealed that nifedipine and cilostazol levels had peaked on day 3 of hospitalization. The formulation of nifedipine was a controlled-release tablet, and the low water solubility of cilostazol may have caused the tablets to adhere and remain in the stomach. Therefore, the drugs had been released into the blood stream several days after hospitalization, leading to delayed-onset NOMI. In cases of overdose, it is crucial to consider the formulation and properties of the involved drugs when determining medical treatment.

Effect of Omeprazole Administration on the Pharmacokinetics of Oral Extended-Release Nifedipine in Healthy Subjects.

Oral extended-release (ER) dosage forms have been used to sustain blood drug levels, reduce adverse events, and improve patient compliance. We investigated potential effects of comedication on pharmacokinetic exposure of nifedipine ER products with different formulation designs and manufacturing processes. A clinical study compared a generic version of nifedipine ER tablet with pH-dependent dissolution behavior with an osmotic pump product with pH independent drug release under fasting condition. In this study, two nifedipine tablet products were tested with or without short-term omeprazole comedication in healthy subjects. Seven-day administration of omeprazole before nifedipine dosing significantly increased the gastric pH, and subsequently increased the geometric least square (LS) means of area under the concentration-time curve from time zero to the last measurable timepoint (AUC0-t ) and maximum plasma concentration (Cmax ) of nifedipine to 132.6% (90% confidence interval (CI): 120.6-145.7%) and 112.8% (90% CI: 100.8-126.3%) for pH-dependent ER tablets, and 120.6% (90% CI: 109.7-132.5%) and 122.5% (90% CI: 113.7-131.9%) for the pH-independent ER tablets, respectively. Similar extent of increase in AUC0-t and Cmax was confirmed in the subpopulations whose gastric pH was ≥ 4 or ≤ 3 in subjects with or without omeprazole administration. Given that similar increases in drug exposures were observed for both pH-dependent and pH-independent nifedipine formulations and the geometric LS mean ratios were between 112% and 133% with and without short-term omeprazole comedication, the gastric pH may have limited effects on omeprazole-induced nifedipine PK changes on the tested formulations. The inhibition of cytochrome P450 3A4 activity may play a significant role causing nifedipine exposure changes for both formulations, which would warrant additional assessment.

Development and Characterization of Gel-Based Buccoadhesive Bilayer Formulation of Nifedipine.

A promising controlled drug delivery system has been developed based on polymeric buccoadhesive bilayered formulation that uses a drug-free backing layer and a polymeric hydrophilic gel buccoadhesive core layer containing nifedipine. The DSC thermogravimetric analysis confirms the drug's entrapment in the gel layer and reveals no evidence of a potential interaction. Various ratios of bioadhesive polymers, including HPMC K100, PVP K30, SCMC, and CP 934, were combined with EC as an impermeable backing layer to ensure unidirectional drug release towards the buccal mucosa. The polymeric compositions of hydrophilic gel-natured HPMC, SCMC, and CP formed a matrix layer by surrounding the core nifedipine during compression. Preformulation studies were performed for all of the ingredients in order to evaluate their physical and flow characteristics. Ex vivo buccoadhesive strength, surface pH, swelling index, in vitro and in vivo drug release, and ex vivo permeation investigations were performed to evaluate the produced gel-based system. Rapid temperature variations had no appreciable impact on the substance's physical properties, pharmacological content, or buccoadhesive strength during stability testing using actual human saliva. It was clear from a histological examination of the ex vivo mucosa that the developed system did not cause any irritation or inflammation at the site of administration. The formulation NT5 was the best one, with a correlation coefficient of 0.9966. The in vitro and in vivo drug release profiles were well correlated, and they mimic the in vitro drug release pattern via the biological membrane. Thus, the developed gel-based formulation was found to be novel, stable, and useful for the targeted delivery of nifedipine.

Virtual Clinical Trials Guided Design of an Age-Appropriate Formulation and Dosing Strategy of Nifedipine for Paediatric Use

The rapid onset of action of nifedipine causes a precipitous reduction in blood pressure leading to adverse effects associated with reflex sympathetic nervous system (SNS) activation, including tachycardia and worsening myocardial and cerebrovascular ischemia. As a result, short acting nifedipine preparations are not recommended. However, importantly, there are no modified release preparations of nifedipine authorised for paediatric use, and hence a paucity of clinical studies reporting pharmacokinetics data in paediatrics. Pharmacokinetic parameters may differ significantly between children and adults due to anatomical and physiological differences, often resulting in sub therapeutic and/or toxic plasma concentrations of medication. However, in the field of paediatric pharmacokinetics, the use of pharmacokinetic modelling, particularly physiological-based pharmacokinetics (PBPK), has revolutionised the ability to extrapolate drug pharmacokinetics across age groups, allowing for pragmatic determination of paediatric plasma concentrations to support drug licensing and clinical dosing. In order to pragmatically assess the translation of resultant dissolution profiles to the paediatric populations, virtual clinical trials simulations were conducted. In the context of formulation development, the use of PBPK modelling allowed the determination of optimised formulations that achieved plasma concentrations within the target therapeutic window throughout the dosing strategy. A 5 mg sustained release mini-tablet was successfully developed with the duration of release extending over 24 h and an informed optimised dosing strategy of 450 µg/kg twice daily. The resulting formulation provides flexible dosing opportunities, improves patient adherence by reducing frequent administration burden and enhances patient safety profiles by maintaining efficacious levels of consistent drug plasma levels over a sustained period of time.

Development and characterization of different dosage forms of nifedipine/indomethacin fixed-dose combinations

Studies have shown that 40 individuals out of 100,000 are diagnosed with rheumatoid arthritis (RA) yearly, with a total of 1.3 million in the United States. Furthermore, the impact of RA in some cases can extend to cardiovascular diseases (CVD), as the studies showed that 84% of RA patients are at risk of developing hypertension. This study aims to design and develop different dosage forms (capsule-in-capsule and three-dimensional (3D) printed tablet) of nifedipine/indomethacin fixed-dose combination (FDC). The hot-melt extrusion (HME) was utilized alone and with fused deposition modeling (FDM) techniques The developed dosage forms were intended to provide delayed-extended and immediate release profiles for indomethacin and nifedipine, respectively. FDC dosage forms were successfully developed and characterized. Nifedipine formulations showed significant improvement in release profiles, having 94% of the drug release at 30 min compared with pure nifedipine, which had a percent release of 2%. Furthermore, the release of indomethacin was successfully delayed at a pH of 1.2 and extended at a pH of 6.8. Differential scanning calorimetry results showed endothermic crystalline peaks at 165 °C and 176 °C for indomethacin and nifedipine, respectively. Moreover, the thermal analysis of all formulations showed the absence of the endothermic peaks indicating complete solubilization of indomethacin and nifedipine in the polymeric carriers. All formulations had post-processing drug content in the range of 95%–98%. Moreover, results from the stability study showed that all formulations were able to remain chemically and physically stable with no signs of recrystallization or degradation. The designed FDC dosage forms could improve the quality of life by enhancing patient compliance and preventing the need for polypharmacy.

Oropharyngeal Angioedema due to Nifedipine Hypersensitivity Post-hemithyroidectomy

Nifedipine, a calcium channel blocker, is generally considered as safe but sublingual administration of immediate release nifedipine (IRN) formulations are sometimes associated with serious side effects. An 82-year-old male was presented with oropharyngeal angioedema, with no history of similar episodes, allergy to drug or food. The symptom began 20 minutes after IRN administration. He was admitted to ICU and a protective endotracheal intubation was performed. Over the first six days, his tongue continued to swell, starting with the right side, progressing to the left, hypopharynx, and epiglottis. Intravenous infusions of prednisolone, diphenhydramine and famotidine, were initiated; however, without improvement. The patient received nanofiltered Berinert® 2000 IU IV, but no improvement. Edema of the tongue reduced slowly after the seventh day and further improved over the next five days. Careful evaluation indicated nifedipine as the chief etiology for angioedema in the patient. IRN may triggers severe hypersensitivity and oropharyngeal angioedema, requiring immediate special care and thus should be used carefully.

Nicardia® XL (Nifedipine Extended Release): Technologically Advanced GITS Formulation Ensures Robust Efficacy and Assured Safety

Nifedipine is a classical dihydropyridine calcium channel blocker (CCB) indicated for the management of hypertension, vasospastic angina and chronic stable angina. Prestigious regulatory bodies like USFDA, EMA, CDSCO and TGA have approved long-acting Nifedipine for the management of hypertension and angina. Nifedipine was 1st introduced in United States as Adalat® (Bayer) in 1981 and in India as Nicardia® (J. B. Chemicals &amp; Pharmaceuticals) in 1985.&#x0D; Conventional Nifedipine shows the rapid onset and short duration of action which results in prompt and marked hypotensive effect but exhibits reflex SNS activation leading to flushing, tachycardia, worsening myocardial ischemia, and cerebrovascular ischemia. Nifedipine gastrointestinal therapeutic system (GITS) formulation addresses many of the concerns surrounding the older formulations of Nifedipine. Nifedipine GITS is a gold standard once-daily formulation of Nifedipine which allows relatively constant plasma drug concentrations over 24 hours. Nifedipine GITS provides a controlled release and gradual onset of action of Nifedipine, avoiding the reflex SNS activation resulting in improved tolerability and compliance.&#x0D; Clinical studies suggest that long-acting formulations of Nifedipine have slightly greater antihypertensive actions than Amlodipine. Nifedipine was also found to be more efficient than other CCBs like Amlodipine, Nicardipine, and Isradipine in resistant hypertensive patients. The addition of Nifedipine GITS to the conventional treatment of angina pectoris is safe and reduces the need for coronary angiography and interventions.&#x0D; Several landmark trials have demonstrated that long-acting Nifedipine improves endothelial function and arterial stiffness and reduces albuminuria, LV hypertrophy, atherosclerotic plaques and cardiovascular and cerebrovascular complications.&#x0D; This comprehensive review focuses on the superiority of the Nifedipine GITS formulation over the conventional Nifedipine and elaborates on the role of long-acting Nifedipine as a CCB of choice for the management of hypertension, resistant hypertension, angina pectoris and coronary artery disease.&#x0D; Keywords – Calcium Channel Blockers, Nifedipine, Long-Acting Nifedipine, Nifedipine GITS, Nifedipine Extended Release, Nicardia XL.

Investigating the interaction between nifedipine- and ritonavir-containing antiviral regimens: A physiologically based pharmacokinetic/pharmacodynamic analysis.

Hypertension is a common comorbidity of patients with COVID-19, SARS or HIV infection. Such patients are often concomitantly treated with antiviral and antihypertensive agents, including ritonavir and nifedipine. Since ritonavir is a strong inhibitor of CYP3A and nifedipine is mainly metabolized via CYP3A, the combination of ritonavir and nifedipine can potentially cause drug-drug interactions. This study provides guidance on nifedipine treatment during and after coadministration with ritonavir-containing regimens, using a physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) analysis. The PBPK/PD models for 3 formations of nifedipine were developed based on the Simcyp nifedipine model and the models were verified using published data. The effects of ritonavir on nifedipine exposure and systolic blood pressure (SBP) were assessed for instant-release, sustained-release and controlled-release formulations in patients. Various nifedipine regimens were investigated when coadministered with or without ritonavir. PBPK/PD models for 3 formulations of nifedipine were successfully established. The predicted maximum concentration (Cmax ), area under plasma concentration-time curve (AUC), maximum reduction in SBP and area under effect-time curve were all within 0.5-2.0-fold of the observed data. Model simulations showed that the inhibitory effect of ritonavir on CYP3A4 increased the Cmax of nifedipine 17.92-48.85-fold and the AUC 63.30-84.01-fold at steady state and decreased the SBP by >40mmHg. Thus, the combination of nifedipine and ritonavir could lead to severe hypotension. Ritonavir significantly affects the pharmacokinetics and antihypertensive effect of nifedipine. It is not recommended for patients to take nifedipine- and ritonavir-containing regimens simultaneously.

Physiologically Based Pharmacokinetic Modeling Approach to Identify the Drug–Drug Interaction Mechanism of Nifedipine and a Proton Pump Inhibitor, Omeprazole

Proton pump inhibitors (PPIs) can affect the intragastric release of other drugs from their dosage forms by elevating the gastric pH. They may also influence drug absorption and metabolism by interacting with P-glycoprotein or with the cytochrome P450 (CYP) enzyme system. Nifedipine is a Biopharmaceutics Classification System (BCS) class II drug with low solubility across physiologic pH and high permeability. Previous studies have demonstrated that drug-drug interaction (DDI) existed between omeprazole and nifedipine with significantly increased systemic exposure of nifedipine in subjects after pre-treatment for 7days with omeprazole compared to the subjects without omeprazole treatment. It was shown that omeprazole not only induced an increase in intragastric pH, but also inhibited the CYP3A4 activity, while CYP3A4-mediated oxidation is the main metabolic pathway of nifedipine. The purpose of this study is to apply a physiologically based pharmacokinetic (PBPK) modeling approach to investigate the DDI mechanism for an immediate release formulation of nifedipine with omeprazole. A previously published model for omeprazole was modified to integrate metabolites and to update CYP inhibition based on the most updated published in vitro data. We simulated the nifedipine pharmacokinetics in healthy subjects with or without the multiple-dose pretreatment of omeprazole (20mg) following oral administrations of immediate-release (IR) (10mg) nifedipine. Nifedipine solubility at different pHs was used to simulate the nifedipine pharmacokinetics for both clinical arms. Multiple sensitivity analyses were performed to understand the impact of gastric pH and the CYP3A4-mediated gut and liver first pass metabolism on the overall nifedipine pharmacokinetics. The developed PBPK model properly described the pharmacokinetics of nifedipine and predicted the inhibitory effect of multiple-dose omeprazole on CYP3A4 activity. With the incorporation of the physiologic effect of omeprazole on both gastric pH and CYP3A4 to the PBPK model, the verified PBPK model allows evaluating the impact of the increase in gastric pH and/or CYP3A4 inhibition. The simulated results show that the nifedipine metabolic inhibition by omeprazole may play an important role in the DDI between nifedipine and omeprazole for IR nifedipine formulation. The developed full PBPK model with the capability to simulate DDI by considering gastric pH change and metabolic inhibition provides a mechanistic understanding of the observed DDI of nifedipine with a PPI, omeprazole.

Development and In vitro Evaluation of Nifedipine Gel Formulations for Anorectal Applications.

Current study focuses on the formulation and characterization of lipophilic and hydrophilic gel formulations of nifedipine to treat anal fissure via anodermal application. Lipophilic gels were prepared with Aerosil grades as gelling agents in bulk oils. Polyethylene glycols, hydroxypropyl methylcellulose, and Carbopol® 974P were used as gelling agents in water and propylene glycol for forming hydrophilic gels. The effect of repeated Freeze-Thaw Cycles (FT-C) on microstructures of the gels was investigated by examining viscosity, rheology and textural properties. Aerosil 200 containing lipophilic gels exhibited thixotropic behavior with plastic flow properties and higher viscosities. Accordingly, their compressibility and adhesiveness increased. FT-C caused notable changes in microstructures and textural properties of the lipophilic gels excluding the formulation containing Aerosil 200-in-isopropyl myristate. Among the hydrophilic gels, the viscosity of Carbopol® 974P gels increased depending on the amount of polymer, triethanolamine and water; these gels featured plastic flow without thixotropic behavior. Their compressibility and adhesiveness were higher than other gel formulations with stable post-FT-C characteristics. The higher flux values of nifedipine were observed from water containing Carbopol® 974P gel. The results of the stability tests showed that the Carbopol® 974P gel had a longer shelf life than the Aerosil 200-in-isopropyl myristate gel.

Development of a UV-Stabilized Topical Formulation of Nifedipine for the Treatment of Raynaud Phenomenon and Chilblains.

Raynaud’s Phenomenon is a vascular affliction resulting in pain and blanching of the skin caused by excessive and prolonged constriction of arterioles, usually due to cold exposure. Nifedipine is a vasodilatory calcium channel antagonist, which is used orally as the first-line pharmacological treatment to reduce the incidence and severity of attacks when other interventions fail to alleviate the condition and there is danger of tissue injury. Oral administration of nifedipine, however, is associated with systemic adverse effects, and thus topical administration with nifedipine locally to the extremities would be advantageous. However, nifedipine is subject to rapid photodegradation, which is problematic for exposed skin such as the hands. The goal of this project was to analyze the photostability of a novel topical nifedipine cream to UVA light. The effect of incorporating the photoprotectants rutin, quercetin, and/or avobenzone (BMDBM) into the nifedipine cream on the stability of nifedipine to UVA light exposure and the appearance of degradation products of nifedipine was determined. Rutin and quercetin are flavonoids with antioxidant activity. Both have the potential to improve the photostability of nifedipine by a number of mechanisms that either quench the intermolecular electron transfer of the singlet excited dihydropyridine to the nitrobenzene group or by preventing photoexcitation of nifedipine. Rutin at either 0.1% or 0.5% (w/w) did not improve the stability of nifedipine 2% (w/w) in the cream after UVA exposure up to 3 h. Incorporation of quercetin at 0.5% (w/w) did improve nifedipine stability from 40% (no quercetin) to 77% (with quercetin) of original drug concentration after 3 h UVA exposure. A combination of BMDBM and quercetin was the most effective photoprotectant for maintaining nifedipine concentration following up to 8 h UVA exposure.

Drug in Adhesive Transdermal Formulation of Valsartan and Nifedipine: Pharmacokinetics and Pharmacodynamics in Rats

Background: The increasing complications associated with hypertension often require a combination of two or more drugs acting through different routes to counter the elevated blood pressure. Objective: The present investigation envisaged at preparing and evaluating a transdermal formulation containing gelled microemulsion drug in adhesive (DIA) patch for simultaneous systemic delivery of valsartan and nifedipine aimed at effective management of hypertension. Methods: An optimized microemulsion was prepared by using Captex® 500 (7.34% w/w), Capmul® MCM (4.24% w/w), Acrysol EL 135 (24.43% w/w), Transcutol P® (5% w/w) and water (58.9% w/w). Gelling was contributed by polyvinylpyrrolidone K 90F and polyethyleneimine where the latter also conferred skin adhesion properties to the patch. DIA patches were evaluated for in vitro drug release as well as in vivo pharmacokinetics and pharmacodynamics in rats. Results: In vitro permeation of nifedipine or valsartan from the selected DIA patch was 10.67-fold and 1.25-fold higher as compared to their aqueous dispersions. The relative bioavailability of nifedipine was 1.34 and that of valsartan was 2.18 from this DIA patch with respect to the oral administration of their aqueous suspension. Conclusion: Transdermal delivery of either drug alone was not effective in reducing methyl prednisolone acetate-induced hypertension, whereas, simultaneous transdermal delivery of both drugs from DIA patch effectively maintained systolic blood pressure at a normal level in these rats for 20 h.

Potential prediction of formulation performance in paediatric patients using biopharmaceutical tools and simulation of clinically relevant administration scenarios of nifedipine and lorazepam.

This study explores the impact of paediatric patient related factors and choice of formulation on the dissolution characteristics of nifedipine and lorazepam, 2 drug substances regularly applied in very young patients and in compounded formulations. Dissolution experiments were designed to reflect clinical practice in a paediatric hospital, with respect to dosage forms, feeding regimens and methods of administration. Solubility studies addressed the influence of age and prandial state. Drug solubility and dissolution experiments were conducted in biorelevant media and adapted age-specific (neonate and infant) media. Dissolution studies were performed with the mini-paddle apparatus and the flow-through cell apparatus. Dissolution of nifedipine formulations was not affected by age-related changes of the fasted state simulated gastrointestinal fluids, and by disintegration of the formulation before administration. However, a significant difference in nifedipine's dissolution rate from commercial tablets and compounded capsules was observed. The dissolution of lorazepam tablets was affected by fasted- vs fed-state media, but it was deemed less likely to be clinically relevant. The significant effect of fed-state media on nifedipine's solubility was considered to have possible clinical relevance since very young patients are almost continuously in a fed state. The in vitro results obtained from these studies reveal the potential of biorelevant solubility and dissolution studies reflecting clinical practice to predict drug performance in paediatric patients.

A randomized controlled trial on the blood pressure-lowering effect of amlodipine and nifedipine-GITS in sustained hypertension.

In a multicenter, randomized trial, we investigated whether the long half-time dihydropyridine calcium channel blocker amlodipine was more efficacious than the gastrointestinal therapeutic system (GITS) formulation of nifedipine in lowering ambulatory blood pressure (BP) in sustained hypertension (clinic systolic/diastolic BP 140-179/90-109mmHg and 24-hour systolic/diastolic BP≥130/80mmHg). Eligible patients were randomly assigned to amlodipine 5-10mg/day or nifedipine-GITS 30-60mg/day. Ambulatory BP monitoring was performed for 24hours at baseline and 4-week treatment and for 48hours at 8-week treatment with a dose of medication missed on the second day. After 8-week treatment, BP was similarly reduced in the amlodipine (n=257) and nifedipine-GITS groups (n=248) for both clinic and ambulatory (24-hour systolic/diastolic BP10.3/6.5 vs 10.9/6.3mmHg, P≥0.24) measurements. However, after missing a dose of medication, ambulatory BP reductions were greater in the amlodipine than nifedipine-GITS group, with a significant (P≤0.04) between-group difference in 24-hour (-1.2mmHg) and daytime diastolic BP (-1.5mmHg). In conclusion, amlodipine and nifedipine-GITS were efficacious in reducing 24-hour BP. When a dose of medication was missed, amlodipine became more efficacious than nifedipine-GITS.

Variability of compounded topical 0.2% nifedipine formulations

AbstractBackgroundThis aim of the study was to conduct a quality analysis of compounded formulations of topical nifedipine 0.2% obtained from retail compounding pharmacies.MethodsNifedipine preparations were purchased in triplicate (refills two weeks apart) from nine commercial compounding pharmacies and assessed for: (1) label and information in compliance with regulations; (2) content homogeneity, determined by content assessment of samples from the top, middle and bottom of each preparation and microscopic assessment of crystals; (3) prescription uniformity (i.e. determining the content of each of the refills compared with the first prescription dispensed); and (4) microbiological contamination.ResultsOnly two providers labelled the product as a compounded product, and only one compounder included a lot or batch number and storage instructions. Of the 81 samples (from nine pharmacies) analysed, only 22 complied with the US Pharmacopoeia standard for potency being 90–115% of label claim; the lowest potency detected was 48.5% and the highest was 157.5%.ConclusionPatients prescribed topical 0.2% nifedipine received compounded formulations that were incorrectly or inappropriately labelled and with considerable variability in potency and content uniformity.

Synthesis and characterization of supramolecular systems containing nifedipine, β-cyclodextrin and aspartic acid

The purpose of this work was to characterize complexes of nifedipine with β-cyclodextrin (β-CD), with and without auxiliary agents, to improve aqueous solubility and the dissolution profile of nifedipine. Complexes were characterized using infrared spectroscopy, thermoanalytical methods, powder X-Ray diffraction, scanning electron microscopy, phase solubility analysis and dissolution studies. Spatial configurations were determined by NMR and further examined using computational techniques. This investigation showed that the amino acid Asp was the most efficient auxiliary agent for multicomponent complexes. The spatial configurations were consistent with those obtained by molecular modelling; evidencing that nifedipine inserted its aromatic ring into β-CD, in all complexes, with Asp interacting with the wide hydrophilic rim of β-CD. The dissolution rates of nifedipine:β-CD:Asp complexes were significantly increased compared to those of the pure drug or nifedipine:β-CD. These results indicate that the nifedipine:β-CD:Asp system is a promising approach for the preparation of optimized formulations of nifedipine.

DIFFERENCES IN 24-H AMBULATORY BLOOD PRESSURE MONITORING (ABPM) IN PATIENTS SWITCHED BETWEEN DIFFERING EXTENDED-RELEASE FORMULATIONS OF NIFEDIPINE: DOSE SCALING BETWEEN 30-MG VS. 60-MG DOSES

Pharmacies frequently switch patients between the two once-daily osmotic pump formulations of nifedipine-extended-release (nifedipine-XL) deemed to be bioequivalent in Canada. We recently demonstrated statistically significant and clinically important differences in 24-h systolic blood pressures (SBP) when patients are switched between the two 60-mg versions of nifedipine-XL (the original two-compartment pump sold under the brand name Adalat XL = AdN and the newer one-compartment pump sold as Mylan-nifedipine-XL = MyN). We report the comparison of SBP results from ABPM studies on patients switched between the two 30-mg versions of nifedipine-XL (AdN and MyN), and contrast with the 60-mg results using the same protocol. Using a randomized-block, cross-over design, 40 patients receiving morning-dosed AdN or MyN 30 mg were studied using 24-h ABPM at the end of each 2-wk daily dosing period. We compared 24-h SBP (06:00 h - 06:00 h) and terminal 8-h SBP (22:00 h - 06:00 h) for each formulation. Mean ± SE 24-h SBP was 132.6 ± 1.6 mmHg with AdN, and 133.5 ± 1.6 mmHg with MyN (p=0.16). For the terminal 8 h, mean ± SE nocturnal SBP was 123.7 ± 2.0 mmHg with AdN and 125.4 ± 1.9 mmHg with MyN (p=0.18). Plots of the SBP 30-mg curves followed the same pattern as the 60-mg formulations. Some patients had terminal 8-h SBP 22 mmHg higher while taking MyN than while receiving AdN. Patients taking the MyN version of 30-mg nifedipine tended to have less blood pressure control. Although this difference was not statistically significant for the 30-mg group as a whole, some individuals experienced large differences when switched. The lesser overall difference seen when switching between the 30-mg versions (vs. with the 60-mg versions) could be due to: a halving of dose effects on SBP at the lower dose; or improvements in the MyN formulation characteristics made in the interval following the prior release of the 60-mg tablet. However, differences in the release pattern between the first vs. zero-order delivery technologies are conserved in the new MyN tablet, although less apparent at the smaller dose size. While not important on a population basis, switching between the 30-mg formulations of nifedipine-XL by pharmacies can still cause unexplained variability in SBP control in some patients, with unintended management consequences. Both nifedipine formulations work, but given the lack of cost differential, avoiding potential SBP inconsistencies from switches between different delivery technologies remains a reasonable precaution.

Virtual bioequivalence for achlorhydric subjects: The use of PBPK modelling to assess the formulation-dependent effect of achlorhydria

Majority of bioequivalence studies are conducted in healthy volunteers. It has been argued that bioequivalence may not necessarily hold true in relevant patient populations due to a variety of reasons which affect one formulation more than the other for instance in achlorhydric patients where elevated gastric pH may lead to differential effects on formulations which are pH-sensitive with respect to release or dissolution. We therefore examined achlorhydria-related disparity in bioequivalence of levothyroxine and nifedipine formulations using virtual bioequivalence within a physiologically-based pharmacokinetic (PBPK) modelling framework. The in vitro dissolution profiles at neutral pH were incorporated into PBPK models to mimic the achlorhydria with in vitro–in vivo relationship established using bio-relevant pH media. The PBPK models successfully reproduced the outcome of the bioequivalence studies in healthy volunteers under the normal conditions as well as under proton pump inhibitor-induced achlorhydria. The geometric mean test/reference ratios for Cmax and AUC between levothyroxine tablet and capsule in patients receiving proton pump inhibitor were 1.21 (90%CI, 1.13–1.29) and 1.09 (90%CI, 1.02–1.17), respectively. Extension of the virtual bioequivalence study to Japanese elderly, who show high incidence of achlorhydria, indicated bio-inequivalence which Cmax and AUC ratios between nifedipine control-released reference and test formulations were 3.08 (90%CI, 2.81–3.38) and 1.57 (90%CI, 1.43–1.74), respectively. Virtual bioequivalence studies through the PBPK models can highlight the need for conduct of specific studies in elderly Japanese populations where there are discrepancies in pH-sensitivity of dissolution between the test and reference formulations.