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At least 19 recordsLinked to original sources
PubMed1995

The determination in human plasma of 1-hydroxy-2-naphthoic acid following administration of salmeterol xinafoate.

The clinical development of salmeterol xinafoate, the 1-hydroxy-2-naphthoic acid salt of salmeterol, a potent long acting beta 2 agonist bronchodilator, has required the development of a method for the determination of 1-hydroxy-2-naphthoic acid (HNA), in human plasma. A sensitive, accurate and precise method was, therefore, required to enable the pharmacokinetic profile to be established. HNA was determined in human plasma using a semi-automated procedure with solid-phase extraction using an automated analytical sample processor (AASP) and high-performance liquid chromatography (HPLC) with fluorescence detection. The method was sensitive to 10 ng ml-1. The method is specific for HNA with respect to endogenous plasma components and has been shown to be robust, accurate and precise. Over four independent assay runs, the relative standard deviations (RSD) of the quality control samples (QC) were 1.6, 2.4 and 5.5% at 180, 100 and 40 ng ml-1, respectively. A pharmacokinetic profile of HNA in man has been established from a single dose kinetic study in healthy volunteers following an oral dose of 500 micrograms salmeterol xinafoate, equivalent to 225 micrograms HNA. Maximum plasma concentrations attained at 1 h after dosing ranged between 35.3 and 66.8 ng ml-1 and were within the calibration range of the assay.

Administration, Oral↗
PubMed1992

Prevention of exercise induced asthma by inhaled salmeterol xinafoate.

The effect of inhaled salmeterol xinafoate, a long acting beta 2 agonist, on exercise induced asthma was studied in a double blind, crossover, and placebo controlled trial. Thirteen asthmatic children with a fall of at least 15% in their forced expiratory volume in one second (FEV1) after a standard exercise test on a motorised treadmill, on separate days performed the same test 1, 5, and 9 hours after a single dose of 50 micrograms salmeterol or placebo. FEV1 was measured before treatment, and before and for 30 minutes after each exercise test. After placebo the number of children with exercise induced asthma was: 10 at 1 hour, 11 at 5 hours, and 12 at 9 hours. Salmeterol prevented exercise induced asthma in all 13 children studied, at 1, 5, and 9 hours. Mean maximum falls in FEV1 after exercise were at 1 hour: salmeterol 2.7% and placebo 24.6%, 5 hours: salmeterol 5.3% and placebo 22.7%; and 9 hours: salmeterol 3.4% and placebo 26.6%. After salmeterol the mean increase in FEV1 was 17.8% at 1 hour, 19.6% at 5 hours, and 19.2% at 9 hours. Inhaled salmeterol prevents exercise induced asthma and produces significant bronchodilatation for at least 9 hours.

Administration, Inhalation↗
PubMed1995

Salmeterol xinafoate in children on high dose inhaled steroids.

BACKGROUND: Current UK and international guidelines on asthma management recommend that, in pediatric patients still symptomatic on treatment with high-dose inhaled corticosteroids, consideration should be given to the introduction of regular twice daily long-acting beta 2-agonists. OBJECTIVE: The purpose of this study was to assess the efficacy and safety of inhaled salmeterol xinafoate 50 micrograms bid via the Diskhaler when added to the existing treatment of children with moderate to severe asthma. METHODS: A 12-week multicenter, double-blind, placebo-controlled, parallel group study was conducted at 78 hospital centers throughout the United Kingdom, involving 210 asthmatic children aged between 4 and 16 years of age. Morning peak expiratory flow (PEF), evening PEF, night-time and daytime symptoms and relief medication usage were recorded daily by the patient or parent over a 12-week treatment period. RESULTS: Compared with placebo, the addition of salmeterol xinafoate to existing high dose inhaled corticosteroid treatment significantly improved mean morning PEF expressed as percent predicted (PEF-PP) during the first 4 weeks of treatment (median increase 6.5 percentage points P < .001). This effect persisted throughout the 12-week treatment period (P < .05). Both groups demonstrated an overall improvement in mean morning PEF-PP, 7.5 percentage points for salmeterol xinafoate and 4 percentage points for placebo. The mean evening PEF-PP followed a similar although less pronounced trend which was significant only during the first 4 weeks of treatment (P = .014). Daytime relief medication and recorded symptoms were reduced significantly in both groups. There was a greater improvement in the number of symptom-free days during the first 4 weeks (P < .01) and the last 4 weeks (P < .05) of treatment for salmeterol xinafoate. The overall incidence and nature of minor adverse events was similar in both groups. CONCLUSIONS: This study demonstrates that the addition of salmeterol xinafoate to inhaled corticosteroid therapy in symptomatic asthmatic children significantly improves morning PEF-PP, and reduces their symptoms and use of relief medication.

Administration, Inhalation↗
PubMed1999

The long-acting beta2-agonist salmeterol xinafoate: effects on airway inflammation in asthma.

Salmeterol xinafoate is an inhaled long-acting beta2-adrenoceptor agonist recently introduced for the treatment of asthma. Both in vitro and animal studies suggest that it may have anti-inflammatory activities of benefit in this disease. To assess this directly, the effects of 6 weeks' treatment with salmeterol on indices of clinical activity, airway dysfunction and inflammation in subjects with stable atopic asthma were investigated. In a double blind study, asthmatic patients were randomized to 6 weeks' treatment with either salmeterol 50 microg twice daily (n=14) or placebo (n=12). They underwent bronchoscopy with bronchoalveolar lavage (BAL) and bronchial biopsy immediately before starting treatment and again after 6 weeks. Treatment with salmeterol improved clinical indices of asthma activity, but there were no changes in BAL differential cell counts or mediator levels, and no change in T-cell numbers or activation status. In the biopsy specimens there were no changes in numbers of inflammatory cells, sub-basement membrane collagen deposition or mast cell degranulation. Regular treatment with salmeterol improves clinical indices of asthma but has no effect on the underlying inflammatory process. These findings strengthen guideline recommendations that long-acting beta2-agonists should not be prescribed as sole antiasthma medication.

Adolescent↗
PubMed1999

Efficacy of salmeterol xinafoate in the treatment of COPD.

STUDY OBJECTIVES: To examine and compare the efficacy and safety of salmeterol xinafoate, a long-acting inhaled beta2-adrenergic agonist, with inhaled ipratropium bromide and inhaled placebo in patients with COPD. DESIGN: A stratified, randomized, double-blind, double-dummy, placebo-controlled, parallel group clinical trial. SETTING: Multiple sites at clinics and university medical centers throughout the United States. PATIENTS: Four hundred eleven symptomatic patients with COPD with FEV1 < or = 65% predicted and no clinically significant concurrent disease. INTERVENTIONS: Comparison of inhaled salmeterol (42 microg twice daily), inhaled ipratropium bromide (36 microg four times a day), and inhaled placebo (2 puffs four times a day) over 12 weeks. RESULTS: Salmeterol xinafoate was significantly (p < 0.0001) better than placebo and ipratropium in improving lung function at the recommended doses over the 12-week trial. Both salmeterol and ipratropium reduced dyspnea related to activities of daily living compared with placebo; this improvement was associated with reduced use of supplemental albuterol. Analyses of time to first COPD exacerbation revealed salmeterol to be superior to placebo and ipratropium (p < 0.05). Adverse effects were similar among the three treatments. CONCLUSIONS: These collective data support the use of salmeterol as first-line bronchodilator therapy for the long-term treatment of airflow obstruction in patients with COPD.

Administration, Inhalation↗
PubMed1994

Salmeterol xinafoate in the treatment of mild to moderate asthma in primary care. UK Study Group.

BACKGROUND: Clinical studies of inhaled salmeterol xinafoate have been conducted mainly in moderately to severely affected asthmatic subjects in hospital settings. This study was conducted to investigate the effectiveness of this drug in patients with milder asthma in primary care. METHODS: A multicentre, double blind, randomised, parallel group comparison of salmeterol xinafoate in a dose of 50 micrograms twice daily with placebo, both administered from a four-place dry powder inhaler (Diskhaler), was performed over six weeks in United Kingdom general practices. RESULTS: A total of 427 asthmatic patients aged 18 years or older were randomised to receive salmeterol or placebo in a 2:1 ratio. Of the total randomised population, 247 patients were previously on short acting bronchodilators alone whilst 180 patients were concurrently receiving up to 400 micrograms inhaled corticosteroid. Mean morning peak expiratory flow rose more in the salmeterol group than in the placebo group (treatment difference 17 l/min, 95% confidence interval 9 to 26 l/min) but there was a smaller, non-significant difference in mean evening peak expiratory flow. Improvements occurred in the salmeterol-treated group compared with placebo for wheeze, shortness of breath, undisturbed nights, and relief medication use, irrespective of concomitant inhaled corticosteroid use. In addition, improvement in activity restriction was seen in the salmeterol group compared with placebo in the subgroup receiving only bronchodilator. CONCLUSIONS: Salmeterol is effective and well tolerated in the short term in mildly asthmatic adult patients irrespective of concomitant use of inhaled corticosteroid therapy.

Adolescent↗
PubMed1994

Salmeterol xinafoate as maintenance therapy compared with albuterol in patients with asthma.

OBJECTIVE: To compare the efficacy and safety of inhaled salmeterol xinafoate, a long-acting beta 2-adrenoceptor agonist, with that of albuterol, a short-acting inhaled beta 2-agonist, in the treatment of asthma. DESIGN: Randomized, double-blind, placebo-controlled, parallel-group study. SETTING: Eleven outpatient clinical centers. SUBJECTS: A total of 322 male and female patients at least 12 years of age with chronic symptomatic asthma requiring daily therapy. INTERVENTION: Patients were treated with salmeterol xinafoate (42 micrograms inhaled twice daily), albuterol (180 micrograms inhaled four times daily), or placebo (four times a day) for 12 weeks; patients in all three groups could use inhaled albuterol as backup medication for breakthrough symptoms. MAIN OUTCOME MEASURES: Serial 12-hour forced expiratory flow in 1 second (FEV1), peak expiratory flow (PEF), asthma symptoms, nocturnal awakenings due to asthma, episodes of asthma exacerbations, and electrocardiography. RESULTS: The mean area under the curve for FEV1 throughout each 12-hour period was consistently greater after a single dose of salmeterol than after two doses of albuterol administered 6 hours apart (P < .001), with the difference ranging from 3.1 to 4.3 L.h. Salmeterol produced an average increase in morning and evening PEF of 26 and 29 L/min, respectively, over pretreatment values compared with decreases of -13 and -3 L/min, respectively, in the albuterol group and -2 L/min both in the morning and evening in the placebo group (P < .001). Patients in the salmeterol group had significantly fewer days and nights with symptoms than did either the albuterol or placebo group (P < .001). Responses to salmeterol were similar at day 1 and at week 12. Adverse events in all treatment groups were equally infrequent, and no clinically significant change in cardiac rhythm was observed with salmeterol treatment. CONCLUSION: Salmeterol inhaled twice daily is more effective than albuterol inhaled four times a day (or as needed) in patients with asthma requiring maintenance therapy. No deterioration of asthma control was observed with the use of salmeterol over a 3-month period.

Administration, Inhalation↗
PubMedDate not supplied

Disposition of salmeterol xinafoate in laboratory animals and humans.

The disposition of [14C]salmeterol xinafoate, a new inhaled beta 2-adrenoceptor agonist with both bronchodilator and antiinflammatory activity, has been studied in laboratory animals and humans following intravenous and oral administration. [14C]Salmeterol was rapidly absorbed in animal species and humans with Cmax observed within 2 hr. Cmax was similar for normalized oral dose level in mice, rats, and rabbits. In dogs, Cmax was higher and reflected the greater oral bioavailability in this species. The plasma t1/2, after intravenous administration, was 5 hr in rats and 2 hr in dogs. The volume of distribution of salmeterol was significantly greater than total body water in both rats (40 liters/kg) and dogs (6 liters/kg) and indicated high tissue uptake of the compound. Plasma clearance was high in rats (95 ml/min/kg) and dogs (30 ml/min/kg). Radioactive drug-related material was widely distributed throughout body tissues in rats. The highest concentrations were present in kidney, liver, gastrointestinal tract, pituitary, lung, heart, and bone marrow. Transfer of radioactive drug-related material across the placental barrier or into milk, studied in rats, was low. In all species the majority of an oral or intravenous dose (55-75%) was excreted in feces. Biliary excretion in rats and dogs accounted for 53% (0-27 hr) and 40% (0-8 hr) of an oral dose, respectively, indicating good absorption across the gastrointestinal tract. Enterohepatic circulation was significant in rats. Salmeterol was cleared predominantly by metabolism in animals and humans.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed2001

Solubility prediction of salmeterol xinafoate in water--dioxane mixtures.

The mole fraction solubility of salmeterol xinafoate was determined in various concentrations of dioxane in aqueous binary mixture. Maximum solubility was observed in 90% v/v dioxane and solubility parameter of the solute was estimated from solubility peak equal to 24.99 MPa(0.5). The predicting capability of four different cosolvency models was also evaluated employing a five data point training set. The solubility data at other cosolvent concentrations were predicted using the trained models, with percentage average errors for 28 drug solubility data sets in water-cosolvent mixtures lying between 12.5 and 15.0%. Further predictive model is proposed for accurate solubility predictions based on a minimum number of experiments. The percentage average error where tested was 10.6%.

Albuterol↗
PubMed2001

Characterization of two polymorphs of salmeterol xinafoate crystallized from supercritical fluids.

PURPOSE: To characterize two polymorphs of salmeterol xinafoate (SX-I and SX-II) produced by supercritical fluid crystallization. METHODS: SX-I and SX-II were crystallized as fine powders using Solution Enhanced Dispersion by Supercritical Fluids (SEDS). The two polymorphs and a reference micronized SX sample (MSX) were characterized using powder X-ray diffractometry (PXRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), aqueous solubility (and dissolution) determination at 5-40 degrees C, BET adsorption analysis, and inverse gas chromatography (IGC). RESULTS: Compared with SX-I, SX-II exhibited a lower enthalpy of fusion, a higher equilibrium solubility, a higher intrinsic dissolution rate, a lower enthalpy of solution (based on van't Hoff solubility plots), and a different FTIR spectrum (reflecting differences in intermolecular hydrogen bonding). Solubility ratio plot yielded a transition temperature (-99 degrees C) below the melting points of both polymorphs. MSX showed essentially the same crystal form as SX-I (confirmed by PXRD and FTIR), but a distinctly different thermal behaviour. Mild trituration of SX-I afforded a similar DSC profile to MSX while prolonged grinding of SX-I gave rise to an endotherm at -109 degrees C, corresponding to solid-solid transition of SX-I to SX-II. Surface analysis of MSX, SX-I, and SX-II by IGC revealed significant differences in surface free energy in terms of both dispersive (nonpolar) interactions and specific (polar) acid-base properties. CONCLUSIONS: The SEDS-processed SX-I and SX-II display high polymorphic purity and distinctly different physical and surface properties. The polymorphs are related enantiotropically with SX-I being the thermodynamically stable form at room temperature.

Albuterol↗
PubMed2003

Thermal analysis of trace levels of polymorphic impurity in salmeterol xinafoate samples.

PURPOSE: To quantify trace levels of polymorphic impurity in two salmeterol xinafoate (SX) Form I samples: granular SX (GSX) produced by fast-cooling crystallization and micronized SX (MSX) prepared from GSX by micronization. METHODS: SX-I and SX-II produced by solution enhanced dispersion by supercritical fluids (SEDS) were the reference polymorphs (100% pure) used for quantitative comparison. The percentage of polymorphic conversion, alpha, of each Form I sample to Form II was measured by differential scanning calorimetry (DSC) as a function of time (i.e., at different scanning speeds). The data were analyzed by the Avrami-Erofe'ev (AE) equation using an iterative fitting computer program. SX-I samples containing 1.24, 4.41, and 13.47% (w/w) of SX-II as physical mixtures were subjected to similar analysis and data treatment. A mathematical relationship based on an instantaneous nucleation model was derived to relate the AE rate constants, k, of pure SX-I and physical mixtures to weight percentage of SX-II. This relationship was then used to calculate the percentage polymorphic impurity of GSX and MSX from their k values. For relative comparison of the Form-II nuclei present, the k values of SX-I, GSX, and MSX were used to calculate their differences in free energy of nucleation. RESULTS: The AE equation affords good (r2 approximately equal to 0.81) to excellent (r2 approximately equal to 0.99) fits of data for the samples. The levels of polymorphic impurity in GSX and MSX are 0.16 and 0.62% (w/w), respectively. Based on the free energy differences of nucleation between the reference SX-I material and the other samples, the number (and size) of the Form II nuclei present in the samples rank in the order: MSX > GSX > SX-I. CONCLUSIONS: DSC is a useful tool for assessing the polymorphic purity of SX materials and possibly other enantiotropic pairs showing similar thermal behavior.

Albuterol↗
PubMed1991

Salmeterol xinafoate. A review of its pharmacological properties and therapeutic potential in reversible obstructive airways disease.

Salmeterol xinafoate, like salbutamol (albuterol), is a saligenin derivative, and a selective beta 2-adrenoceptor agonist. It produces bronchodilation for at least 12 hours following inhalation of a single 50 micrograms dose. Salmeterol is intended for regular twice-daily treatment of reversible airways obstruction and not for immediate symptomatic relief, and when used in this manner, 50 micrograms twice daily is more effective than salbutamol 200 micrograms or terbutaline 500 micrograms administered 4 times daily, or individually titrated oral doses of theophylline in improving objective and subjective criteria of efficacy in patients with mild to moderate asthma. Salmeterol 100 micrograms inhaled twice daily may provide better control than the lower dose in patients with severe asthma. The long duration of effect of salmeterol makes it particularly suitable for treating patients with nocturnal asthma in whom it improves sleep quality. The place of salmeterol, like that of other beta 2-adrenoceptor agonists used regularly in the treatment of asthma, is being debated. Patients in need of regular beta 2-agonist therapy should also be regarded as candidates for inhaled corticosteroids to counteract underlying inflammation. Thus, salmeterol may be particularly useful in patients requiring regular treatment with beta 2-agonists for nocturnal asthma and results of trials in progress involving large numbers of patients are awaited with interest.

Administration, Inhalation↗
PubMedDate not supplied

Salmeterol xinafoate: a review of its pharmacological properties and therapeutic potential in reversible obstructive airways disease.

Salmeterol xinafoate, like salbutamol (albuterol), is a saligenin derivative, and a selective beta 2-adrenoceptor agonist. It produces bronchodilation for at least 12 hours following inhalation of a single 50 micrograms dose. Salmeterol is intended for regular twice-daily treatment of reversible airways obstruction and not for immediate symptomatic relief, and when used in this manner. 50 micrograms twice daily is more effective than salbutamol 200 micrograms or terbutaline 500 micrograms administered 4 times daily, or individually titrated oral doses of theophylline in improving objective and subjective criteria of efficacy in patients with mild to moderate asthma. Salmeterol 100 micrograms inhaled twice daily may provide better control than the lower dose in patients with severe asthma. The long duration of effect of salmeterol makes it particularly suitable for treating patients with nocturnal asthma in whom it improves sleep quality. The place of salmeterol, like that of other beta 2-adrenoceptor agonists used regularly in the treatment of asthma, is being debated. Patients in need of regular beta 2-agonist therapy should also be regarded as candidates for inhaled corticosteroids to counteract underlying inflammation. Thus, salmeterol may be particularly useful in patients requiring regular treatment with beta 2-agonists for nocturnal asthma and results of trials in progress involving large numbers of patients are awaited with interest.

Administration, Inhalation↗
PubMed2005

Validation of a reverse-phase high performance liquid chromatographic method for concurrent assay of a weak base (salmeterol xinafoate) and a pharmacologically active steroid (fluticasone propionate).

The analysis of weakly basic drugs such as salmeterol xinafoate (SX) by reverse-phase liquid chromatography remains a problem, particularly when present in combination with other drugs such as steroids and weak acids. This study describes the validation of an assay for a weakly basic drug, salmeterol (SB), its weakly acidic counter-ion, 1-hydroxy-2-naphthoic acid (XA), and the neutral glucocorticoid, fluticasone propionate (FP) using a second-generation silica stationary phase (Inertsil ODS-2). The assay utilized an Inertsil ODS-2 base-deactivated 250 mm x 4.6mm, 5 microm HPLC column, with 75:25 methanol:0.6% aqueous ammonium acetate as the mobile phase. Under these near neutral conditions, SB demonstrated a good peak shape (tailing factor=1.21+/-0.02, n=85). The method provided a short analysis time: XA, t(R)=2.96 min; SB, t(R)=5.23 min and FP, t(R)=7.01 min. The assay displayed good sensitivity for both XA (LOD for SX=0.22 microgmL(-1)) and SB (LOD for SX=0.26 microgmL(-1)). The limit of detection for FP was 0.19 microgmL(-1). Neither of the drugs was found to interfere in the determination of the other and the assay accuracy (% recovery) was high (the recoveries were: 99.58+/-1.85% for XA, 99.49+/-1.88% for SB and 100.24+/-1.28% for FP). The assay reproducibility was determined with a mean coefficient of variance for the five calibration concentrations of XA=0.71+/-0.18%; SB=1.11+/-0.64% and FP=0.92+/-0.14%. Analysis of a pressurized metered dose inhaler formulation demonstrated recovery of the analytes that are within pharmacopoeial limits. It was shown that RP-HPLC was suitable for the high throughput analysis of the combination of SX and FP.

Albuterol↗
PubMed2004

Lactose surface modification by decantation: are drug-fine lactose ratios the key to better dispersion of salmeterol xinafoate from lactose-interactive mixtures?

PURPOSE: The role of fine lactose in the dispersion of salmeterol xinafoate (SX) from lactose mixtures was studied by modifying the fine lactose concentration on the surface of the lactose carriers using wet decantation. METHODS: Fine lactose was removed from lactose carriers by wet decantation using ethanol saturated with lactose. Particle sizing was achieved by laser diffraction. Fine particle fractions (FPFs) were determined by Twin Stage Impinger using a 2.5% SX mixture, and SX was analyzed by a validated high-performance liquid chromatography method. Adhesion forces between probes of SX and silica and the lactose surfaces were determined by atomic force microscopy. RESULTS: FPFs of SX were related to fine lactose concentration in the mixture for inhalation grade lactose samples. Reductions in FPF (2-tp 4-fold) of Aeroflo 95 and 65 were observed after removing fine lactose by wet decantation; FPFs reverted to original values after addition of micronized lactose to decanted mixtures. FPFs of SX of sieved and decanted fractions of Aeroflo carriers were significantly different (p < 0.001). The relationship between FPF and fine lactose concentration was linear. Decanted lactose demonstrated surface modification through increased SX-lactose adhesion forces; however, any surface modification other than removal of fine lactose only slightly influenced FPF. CONCLUSIONS: Fine lactose played a key and dominating role in controlling FPF. SX to fine lactose ratios influenced dispersion of SX with maximum dispersion occurring as the ratio approached unity.

Administration, Inhalation↗
PubMed2001

Efficacy of salmeterol xinafoate in horses with recurrent airway obstruction.

OBJECTIVE: To determine the onset, magnitude, and duration of bronchodilation after administration of aerosolized salmeterol xinafoate in horses with recurrent airway obstruction. DESIGN: Randomized controlled study ANIMALS: 6 horses with recurrent airway obstruction. Procedure Horses received aerosolized salmeterol (210 microg) or no treatment, using a crossover design. Salmeterol was administered, using a mask designed for aerosol delivery in horses. Subjective rating of airway obstruction (RAO), maximal change in pleural pressure (deltaPplmax), and pulmonary resistance (RL) were determined at baseline; 5, 15, and 30 minutes; and 1, 2, 4, 6, 8, 10, and 12 hours after administration of salmeterol and in horses that did not receive treatment. RESULTS: The deltaPpl and RL were improved 15 minutes through 6 hours after administration of salmeterol, compared with values obtained from horses receiving no treatment. The RAO was improved 15 minutes through 2 hours after administration of salmeterol. The maximal response to salmeterol was evident 30 to 60 minutes after administration and was characterized by a 59 + 19% decrease in deltaPpl and a 56 +/- 13% decrease in RL. The deltaPpl and RL were not different from baseline values 8 hours after salmeterol administration. CONCLUSIONS AND CLINICAL RELEVANCE: Duration of action of salmeterol in these horses was approximately 6 hours. Maximal bronchodilation was somewhat delayed (30 to 60 minutes), and the magnitude of response was similar to that of short-acting beta2-adrenergic agonists. Salmeterol provides moderately sustained bronchodilation in horses with recurrent airway obstruction and may be an effective drug for long-term control of this condition.

Administration, Inhalation↗
PubMed2005

Surface roughness contribution to the adhesion force distribution of salmeterol xinafoate on lactose carriers by atomic force microscopy.

Adhesion force distributions of silica spheres (5 and 20 microm) and salmeterol xinafoate (4 microm) particles with inhalation grade lactose surfaces and spin coated lactose films were determined by atomic force microscopy (AFM) to investigate the influence of surface roughness on the force distributions. The roughness of lactose particles and films was determined by both AFM and confocal microscopy (CM); the lactose particles showed RMS R(q) values between 0.93 and 2.2 microm. The adhesion force distributions for silica and SX probes were significantly different for the different lactose carriers and broad, e.g., the adhesion force distribution between a 5 microm silica sphere and lactose particles ranged from 5 to 105 nN. This contrasted with distributions on smooth spin coated lactose films (RMS R(q) of 0.28 nm) which were not significantly different and were narrow, e.g., the adhesion force distribution between a 5 microm silica sphere and spin coated lactose films was between 42 and 68 nN. In addition, no significant difference in adhesion force distribution occurred with silica probe size on the lactose carrier surface. The use of X-ray photoelectron spectroscopic analysis confirmed that the lactose surfaces were free of impurities that might contribute to variation in adhesion. Although the almost atomically flat films showed some adhesion variability, the surface roughness of the lactose particles was a major contributing factor to the broad distributions seen in this study.

Adhesiveness↗
PubMed2002

Influence of polymorphism on the surface energetics of salmeterol xinafoate crystallized from supercritical fluids.

PURPOSE: To characterize the surface thermodynamic properties of two polymorphic forms (I and II) of salmeterol xinafoate (SX) prepared from supercritical fluids and a commercial micronized SX (form 1) sample (MSX). METHODS: Inverse gas chromatographic analysis was conducted on the SX samples at 30, 40, 50, and 60 degrees C using the following probes at infinite dilution: nonpolar probes (NPs; alkane C5-C9 series); and polar probes (PPs; i.e., dichloromethane, chloroform, acetone, ethyl acetate, diethyl ether, and tetrahydrofuran). Surface thermodynamic parameters of adsorption and Hansen solubility parameters were calculated from the retention times of the probes. RESULTS: The free energies of adsorption (- deltaG(A)) of the three samples obtained at various temperatures follow this order: SX-II > MSX approximately/= SX-I for the NPs; and SX-II > MSX > SX-I for the PPs. For both NPs and PPs, SX-II exhibits a less negative enthalpy of adsorption (deltaH(A)) and a much less negative entropy of adsorption (ASA) than MSX and SX-I, suggesting that the high -AGA of SX-II is contributed by a considerably reduced entropy loss. The dispersive component of surface free energy (gammas(D)) is the highest for MSX but the lowest for SX-II at all temperatures studied, whereas the specific component of surface free energy of adsorption (-deltaG(A)SP) is higher for SX-II than for SX-I. That SX-II displays the highest -deltaG(A) for the NP but the lowest gammasD of all the SX samples may be explained by the additional -AGA change associated with an increased mobility of the probe molecules on the less stable and more disordered SX-II surface. The acid and base parameters, K(A) and K(D) that were derived from deltaH(A)SP reveal significant differences in the relative acid and base properties among the samples. The calculated Hansen solubility parameters (deltaD, deltap, and deltaH) indicate that the surface of SX-II is the most polar and most energetic of all the three samples in terms of specific interactions (mostly hydrogen bonding). CONCLUSIONS: The metastable SX-II polymorph possesses a higher surface free energy, higher surface entropy, and a more polar surface than the stable SX-I polymorph.

Albuterol↗