CYP2C9*3 gene variant contributes independently to glycaemic control in patients with type 2 diabetes treated with glibenclamide.

WHAT IS KNOWN AND OBJECTIVE: Glibenclamide is a prescribed glucose-lowering medication for diabetes, but there are interindividual variations in the therapeutic response. In this cross-sectional study, the aim was to explore the association of genetic variants in CYP2C9, ABCC8, KCNJ11 and TCF7L2 with good glycaemic control in Mexican type 2 diabetes (T2D) treated with glibenclamide. METHODS: Patients with T2D receiving treatment with glibenclamide or glibenclamide plus metformin were included. Patients with A1C ≤ 7% were considered to have good glycaemic control, whereas patients with A1C ≥ 8% were considered having poor glycaemic control. Genotyping was performed by real-time PCR using TaqMan probes for the genetic variants. Association was performed by calculating OR with 95% confidence intervals (95% CI). For the multivariate analysis, a multiple logistic regression was performed including the confounding variables age, exercised, BMI, glibenclamide dose, time with T2D and concomitant metformin. RESULTS AND DISCUSSION: Four hundred and four patients were included in the study, median age of the participants was 50 years (IQR 11.0), the median time with disease was 6 years (IQR 8.0), 118 (29.2%) were men, and 243 (60.1%) received glibenclamide in combination with metformin. CYP2C9*3 variant was associated with good glycaemic control (OR = 2.747 [95% CI, 1.194-6.324]), whereas the variants, CYP2C9*2, TCF7L2 rs7903146 and rs12255372, ABCC8 rs757110 and KCNJ11 rs5219, were not. In the multivariate analysis, the CYP2C9*3 variant maintained its association (OR = 2.779 [95% CI, 1.142-6.763]). WHAT IS NEW AND CONCLUSION: The findings suggest that CYP2C9*3 genetic variant independently contributes to good glycaemic control of patients with type 2 diabetes treated with glibenclamide.

Study of the diversity and short-chain fatty acids production by the bacterial community in overweight and obese Mexican children.

Obesity and overweight are health problems of multifactorial etiology, which may include changes in the microbiome. In Mexico, more than 30 % of the child population between 5 and 11 years of age suffer from being overweight or are obese, which makes it a public health issue in progress. The purpose of this work was to measure the short-chain fatty acid concentration by high-performance liquid chromatography (HPLC), and to characterize the bacterial diversity by ion torrent semiconductor sequencing, of 16S rDNA libraries prepared from stools collected from a sample of well-characterized Mexican children for normal weight, overweight, and obese conditions by anthropometric and biochemical criteria. We found that triglyceride levels are increased in overweight and obese children, who presented altered propionic and butyric acid concentrations in feces. In addition, although the colon microbiota did not show a clear bacterial dysbiosis among the three conditions, the abundance of some particular bacteria was changed with respect to normal controls. We conclude from our results that the imbalance in the abundance of at least nine different bacteria as well as altered short-chain fatty acid concentration in feces is associated to the overweight and obese conditions of Mexican children.

Vectorial role of Acanthamoeba in Legionella propagation in water for human use.

Legionella spp. is the causative agent of Legionnaires' disease and is transmitted through aerosols emanating from man-made water systems. Legionella resistance to water treatments has been related to its association with environmental amoebae such as Acanthamoeba. Due to the high presence of this protozoon in Spain and the high rate of notification of Legionnaires' disease of this country, the aims of this work were to study the coexistence of these bacteria and protozoa in water as well as their interaction. The usefulness of Acanthamoeba co-culture for the isolation of environmental Legionella was also studied. For this purpose, 70 water samples were collected in 2011 from three Drinking Water Treatment Plants, three Wastewater Treatment Plants and five Natural Pools in Spain. Acanthamoeba was found by PCR in 87.1% (61/70) samples and, by culture in 85.7% (60/70) samples. Legionella was detected by PCR in 58.6% (41/70) of water samples, in 5.7% (4/70) by agar culture and 75.7% (53/70) by Acanthamoeba co-culture. From the 54 Acanthamoeba water isolates, Legionella was detected in 43 of them independently of Acanthamoeba's genotype (T3, T4 and T11). Legionella feeleii, Legionella birminghamiensis, Legionella gresilensis/berliardensis, Legionella fairfieldensis, Legionella drozanski and Legionella falloni were identified. In conclusion, our results showed that environmental Acanthamoeba is infected by Legionella to a high percentage, and due to its ubiquity, high resistance and its pathogenic potential per se, new methods for its elimination should be studied. Also, the high effectivity of Acanthamoeba co-culture for Legionella detection has been shown.

Brote de silicosis en trabajadores españoles de conglomerados de cuarzo / Outbreak of silicosis in Spanish quartz conglomerate workers

El objetivo del estudio es describir las características epidemiológicas y clínicas de un brote de silicosis ocupacional y las condiciones de trabajo asociadas. Se consideraron como casos a todos los hombres diagnosticados de silicosis entre julio de 2009 y mayo de 2012 por la unidad de neumología del Hospital Universitario de Puerto Real (Cádiz) que trabajaban en la industria del corte, tallado y acabado de la piedra. Para determinar el número potencial de trabajadores expuestos se elaboró un censo de los lugares de trabajo que utilizaban conglomerados de cuarzo. A los pacientes incluidos en el estudio se les realizó una encuesta telefónica sobre exposiciones ocupacionales y se revisaron sus historias clínicas. La silicosis se diagnosticó en 46 hombres, que tenían una edad mediana de 33 años y una mediana de 11 años trabajando en la fabricación de encimeras. De estos casos, el 91,3% fue diagnosticado de silicosis crónica simple con una tomografía axial computarizada de alta resolución (TACAR) anormal. Un paciente falleció durante el período de estudio. Se detectó tanto un incumplimiento frecuente de las medidas de prevención y control por parte del empleador, como fallas en los sistemas de protección ambientales e individuales. En conclusión, el uso de nuevos materiales de construcción tales como los conglomerados de cuarzo ha incrementado la incidencia de silicosis por exposiciones laborales intensivas en el contexto de una alta demanda impulsada por el auge en la construcción. Esta exposición generalizada representa un riesgo si no se toman medidas preventivas adecuadas

The aim of the study is to describe the epidemiological and clinical characteristics of an outbreak of occupational silicosis and the associated working conditions. Cases were defined as men working in the stone cutting, shaping, and finishing industry in the province of Cádiz, diagnosed with silicosis between July 2009 and May 2012, and were identified and diagnosed by the department of pulmonology of the University Hospital of Puerto Real (Cádiz). A census of workplaces using quartz conglomerates was carried out to determine total numbers of potentially exposed workers. A patient telephone survey on occupational exposures and a review of medical records for all participants were conducted. Silicosis was diagnosed in 46 men with a median age of 33 years and a median of 11 years working in the manufacturing of countertops. Of these cases, 91.3% were diagnosed with simple chronic silicosis, with an abnormal high-resolution computerized tomography (HRCT) scan. One patient died during the study period. Employer non-compliance in prevention and control measures was frequently reported, as were environmental and individual protection failures. In conclusion, the use of new construction materials such as quartz conglomerates has increased silicosis incidence due to intensive occupational exposures, in the context of high demand fuelled by the housing boom. This widespread exposure poses a risk if appropriate preventive measures are not undertaken

A year-long study of Cryptosporidium species and subtypes in recreational, drinking and wastewater from the central area of Spain.

A year-long longitudinal study was undertaken to evaluate the presence of Cryptosporidium spp. in drinking water treatment plants (DWTPs), wastewater treatment plants (WWTPs) and freshwater bathing beaches (FBBs) from the central area of Spain. Water samples were collected according to USEPA Method 1623, and concentrated by the IDEXX Filta-Max® system. Cryptosporidium species were detected based on PCR-restriction fragment length polymorphism and sequence analyses of the ssuRNA gene. C. hominis and/or C. parvum isolates were subtyped by DNA sequencing of the Gp60 gene. Among 150 samples, 23 (15.3%) were positive by IFAT and 40 (26.7%) by PCR. Cryptosporidium spp. was more frequent in WWTPs (26.2 and 50.8%) and FBBs (12.5 and 17.5%) by IFAT and PCR respectively. Effluent waters from DWTPs were negative for this parasite suggesting that they are suitable for public use. Tertiary treatment in the WWTPs demonstrated a high removal efficiency of Cryptosporidium in the samples evaluated. Cryptosporidium species identified included C. hominis, C. parvum, C. ubiquitum, C. andersoni and C. muris. Subtyping analysis revealed C. hominis IbA10G2 and IeA11G3T3 alleles, which is the first report of the latter in water samples. Cryptosporidium highest frequency was observed in winter and spring. Our data provide information about the occurrence and diversity of Cryptosporidium in water of human use from the central area of Spain.

A year long study of the presence of free living amoeba in Spain.

Free-living amoeba such as Acanthamoeba and Balamuthia mandrillaris can act as opportunistic parasites on a wide range of vertebrates and they are becoming a serious threat to human health due to the resistance of their cysts to harsh environmental conditions, disinfectants, some water treatment practices and their ubiquitous distribution. This work was carried out in order to study the presence of these free-living amoebae (FLA) and their possible seasonality in a continental-Mediterranean climate in different types of water. For this purpose, a total of 223 water samples were collected during one year from four drinking water treatment plants (DWTP), seven wastewater treatment plants (WWTP) and six locations of influence (LI) on four river basins from Spain. Water samples were concentrated using the IDEXX Filta-Max(®) system and analyzed by a triplex real time PCR that detects Acanthamoeba, B. mandrillaris and Naegleria fowleri. Agar plates were also seeded for Acanthamoeba culture. From the three FLA studied, N. fowleri was not detected in any sample while B. mandrillaris was found at the entrance of a DWTP; this being, to our knowledge, the first report of these protozoa in water worldwide. On the other hand, the presence of Acanthamoeba observed was higher, 94.6% of the studied points were positive by real time PCR and 85.2% by culture, resulting in 99.1% positive for Acanthamoeba with both methods. All genetically analyzed Acanthamoeba were genotype T4 but nine different T4/DF3 sequences were observed, three of them being described for the first time, assigning new codes. No seasonal distribution of Acanthamoeba was found. These facts should serve as a warning to contact lens wearers of the risk of a poor hygiene when handling their contact lenses. It should also serve as a signal to physicians to consider FLA as a possible causative agent of nervous system infections as well as Acanthamoeba keratitis due to their high environmental presence shown in this study.

Molecular characterization of Acanthamoeba isolated in water treatment plants and comparison with clinical isolates.

A total of 116 samples (44 clinical specimens and 72 environmental samples) have been analyzed for the presence of Acanthamoeba. The environmental samples (ESs) were collected from four drinking water treatment plants (DWTP, n=32), seven wastewater treatment plants (n=28), and six locations of influence (n=12) on four river basins from the central area of Spain (winter-spring 2008). Water samples were concentrated by using the IDEXX Filta-Max(®) system. Acanthamoeba was identified in 65 of the 72 ESs by culture isolation (90.3%) and 63 by real-time PCR (87.5%), resulting in all sampling points (100%) positive for Acanthamoeba when considering both techniques and all the time period analyzed. Nine of the 44 clinical specimens were positive for Acanthamoeba. Seventeen Acanthamoeba strains (eight from four DWTP and nine from clinical samples) were also established in axenic-PYG medium. Twenty-four of the ESs and the 17 Acanthamoeba sp. strains were genotyped as T4/1, T4/8, and T4/9. The eight strains isolated from the DWTP samples were inoculated in nude mouse to ascertain their potential pathogenicity in this model. Animals that were inoculated died or showed central nervous system symptoms 9 days post-inoculation. Examination of immunofluorescence-stained brain and lung tissue sections showed multiple organisms invading both tissues, and re-isolation of throphozoites was successful in these tissues of all infected animals. For the first time, potentially pathogenic Acanthamoeba T4 has been detected in 100% of different types of water samples including tap water and sewage effluents in the central area of Spain suggesting a potential health threat for humans especially for the contact lens wearers.

Differences between rheumatology attending physicians and training residents in the management of rheumatoid arthritis in Spain.

OBJECTIVE: To evaluate the variability in the characteristics and management of rheumatoid arthritis (RA) patients between rheumatology attending physicians and training residents in Spain. METHODS: A retrospective medical record (MR) review was performed in a probabilistic sample of 1379 RA patients from 46 centres distributed in 16 of the 19 autonomous communities (AC) of Spain. RA patients' sociodemographic and clinical characteristics, healthcare resources use, and their single responsible physician's (defined as an identifiable single physician who attended the patient in more than 75% of visits) characteristics were recorded following a standardized protocol. Multivariate analyses were performed to assess differences in the characteristics and management of RA patients between attending physicians and training residents. RESULTS: A total of 1205 RA patients had a single responsible physician and were analysed (nearly 75% women with rheumatoid factor positive and more than 25% with persistent active disease), 49 of whom were followed by training residents and 1156 by attending physicians. In the multivariate analyses, irrespective of patient and disease characteristics, training residents' patients reported more hospital admissions, laboratory tests, and imaging techniques compared to attending physicians. Training residents also less frequently used combined therapy with disease-modifying antirheumatic drugs (DMARDs). CONCLUSION: Training residents and attending physicians differ in RA patients' care. More efforts in training programmes are necessary to guarantee proper RA management and to improve the profile of the future rheumatologists.

Hematuria masiva en una paciente con artritis reumatoide / Massive hematuria in a patient with rheumatoid arthritis

Describimos el caso de una paciente de 61 años diagnosticada de artritis reumatoide. Desarrolló hematuria masiva con expulsión de coágulos sanguíneos; una biopsia de la mucosa vesical reveló amiloidosis secundaria. La amiloidosis secundaria sintomática de la vejiga es muy rara. Solamente se han descrito 22 casos en la bibliografía. La mayoría de estos casos tenía enfermedades reumáticas, más frecuentemente artritis reumatoide (AR) y espondilitis anquilosante (EA). Creemos que es necesario tener en cuenta la posibilidad de amiloidosis secundaria de la vejiga cuando el reumatólogo se enfrente a un paciente con artritis reumatoide y hematuria macroscópica (AU)

We describe the case of a 61-year-old woman with a diagnosis of rheumatoid arthritis. She developed massive hematuria with expulsion of blood clots. Biopsy of the vesical mucosa revealed secondary amyloidosis. Symptomatic amyloidosis of the bladder is highly infrequent and only 22 cases have been reported in the literature. Most reported patients had rheumatic disease, especially rheumatoid arthritis and ankylosing spondylitis. The possibility of secondary amyloidosis of the bladder should be suspected in patients with rheumatoid arthritis and gross hematuria (AU)

B cell activation in rheumatoid arthritis patients under infliximab treatment.

OBJECTIVE: To determine whether anti-TNF alpha (infliximab) treatment affects B cell activation in patients with rheumatoid arthritis (RA) METHODS: B cell activation was analyzed in fifteen anti-TNF-treated RA patients. CD23 expression was used as a B cell activation marker and was studied before and after three months of infliximab treatment. PBMC were stimulated with anti-CD3 mAb during 18 h and were separated by rosseting into E+ and E-cells. B cells were assessed in E-population by double staining with CD19 and CD23. ELISA assays were used to assess both soluble TNF alpha and circulant immune complexes (CIC) containing TNF alpha. We also used B cells from tonsils to establish the relationship between B cell activation and TNF alpha CIC. RESULTS: The proportion of B cells expressing CD23 was higher before infliximab exposure than after treatment (48.3 +/- 16.7 versus 29.5 +/- 12.5, p = 0.007). T-B cell interactions were assessed by means of blocking antibodies to CD154, CD40, CD69, and CD18; these interactions were not specially affected by infliximab treatment. We could demonstrate CIC containing TNF alpha after infliximab treatment, these CIC, similarly to others IgG-containing immune complexes, were capable to downregulate CD23 on B cells. CONCLUSIONS: Infliximab treatment in RA downregulates CD23 expression on T-cell activated B cells. This downregulation is connected with the presence of CIC containing TNF alpha. Presumably, the Fc gamma RIIb1 endows IgG-containing immune complexes, as TNF alpha-anti-TNF alpha, with the capacity to regulate B cells and inflammatory cells.

Evolución de la mortalidad por cáncer de pulmón en la provincia de Cádiz (1975-1995) / Evolution of lung cancer mortality in the province of Cadiz

Propósito: Conocer la evolución de la mortalidad por cáncer de pulmón en la provincia de Cádiz durante el periodo comprendido entre los años 1975 y 1995.Materia y métodos: Se recogieron los datos de los Boletines Estadísticos que acompañan a los Certificados de Defunción con el diagnóstico de "cáncer de pulmón" (CIE 8ª y CIE 9ª) de los 44 municipios que componen la provincia de Cádiz durante los años 1975 a 1995. Se utilizaron indicadores estadísticos sencillos: tasa específica de mortalidad, tasa truncada (> 50 años) y tasa de masculinidad. El ajuste de tasas se realizó por el método directo y la población de referencia fue la europea. Resultado: Se produjeron 6.947 casos de fallecimiento por cáncer de pulmón (19,32 por ciento de todas las muertes por neoplasias), correspondiendo el 92,10 por ciento a hombres. Destaca la clara tendencia al alza de las tasas específicas. El porcentaje de incremento en varones fue del 110,51 por ciento y en mujeres del 74,88 por ciento. Conclusiones: El exceso de mortalidad por cáncer de pulmón en la provincia de Cádiz se ha intentado explicar por diversas causas (industrias contaminantes, consumo de tabaco, desigualdades sociales, etc.), no obstante son necesarios estudios epidemiológicos que justifiquen estos resultados (AU)

Radiopharmacokinetics, renal clearance and dosimetry of 99mTc-MAG3.

BACKGROUND: Technetium-99m-mercaptoacetyltriglycine (99mTc-MAG3) is a radiopharmaceutical for tubular function and can be prepared with 99m-technetium and the ligand Bz-MAG3 (Instituto Nacional de Investigaciones Nucleares, Mexico City). No radiopharmacokinetic parameters have been found for the healthy adult Mexican population with 99mTc-MAG3, prepared with the nationally produced or imported Bz-MAG3 kit. METHODS: The radiopharmacokinetic parameters and the clearance of 99mTc-MAG3 in seven healthy Mexican volunteers were determined by the single- and multi-sample methods. Computer programs were used for the calculations. RESULTS: Using several plasma samples from 0-43 min and the BIEXP program, it was shown that 99mTc-MAG3 follows a two-compartment model of distribution, with an apparent volume in the central compartment Vdcc = 3.8 + 0.7 l, a volume of distribution at steady state Vdss = 6.7 + 1.0 l, T1/2 alpha = 0.07 + 0.02 h-1, T1/2 beta = 0.49 + 0.15 h-1, mean residence time MRT = 0.60 + 0.17 h and clearance = 208 + 57 (ml/min)/1.73 m2. In comparison, the clearance value with a single sample drawn 43 min post-injection and calculated with Tauxe's formula was 193 +/- 59 (ml/min)/m2. CONCLUSIONS: The 15 ml difference between the two methods is neither statistically different (p = 0.11) nor important for routine clinical studies. The single-sample method is recommended because it is reliable and can be done at the same time that the dynamic renal scan is acquired. Estimated absorbed radiation dose was calculated for several organs.

Usefulness of the pain-induced functional impairment model to relate plasma levels of analgesics to their efficacy in rats.

In this work we show that the pain-induced functional impairment model (PIFIR) can be used with cannulated rats as a useful procedure for pharmacokinetic/pharmacodynamic modelling. This model evaluates analgesia by measuring motor impairment of the right limb after intra-articular administration of uric acid. Time of contact with a rotating cylinder is referred to the control limb. We studied the pharmacokinetic and pharmacodynamics of naproxen after six peroral doses to Wistar rats, and we examined the adjuvant action of caffeine with naproxen. Surgery and blood sampling did not produce any difference on functional impairment either in rats without uric acid or in the dysfunction produced by uric acid. The relation between naproxen plasma concentration and the analgesic effect was obtained with few rats. Caffeine alone did not produce any significant modification in functional impairment but the co-administration significantly increased the effect of naproxen. Plasma levels of naproxen did not change when caffeine was co-administered. The PIFIR model with blood sampling is a suitable method for pharmacokinetic/pharmacodynamic relationship studies and is specially useful to characterize drug-drug interactions.

Relationship between naproxen plasma concentration and its anti-inflammatory effect in experimental hepatitis.

The relationship between the plasma concentration and the anti-inflammatory effect of naproxen (CAS 22204-53-1) after oral administration of a 6 mg.kg-1 dose was studied in rats with galactosamine-induced acute hepatitis and under control conditions. In control animals naproxen peak plasma levels of 35 +/- 0.4 micrograms.ml-1 were reached in 0.5 +/- 0 h. Concentration then decayed, half-life being 5.2 +/- 0.4 h. AUC was 131 +/- 5 micrograms.h.ml-1. In intoxicated rats peak plasma levels of 29 +/- 0.3 micrograms.ml-1 were reached in 0.7 +/- 0.1 h, half-life was increased to 11.1 +/- 1.3 h, and the AUC reached 259 +/- 21 micrograms.h.ml-1. In control rats the protective effect of naproxen against carrageenan-induced inflammation increased slowly, reaching a maximum of 38% in 4 h. The protective effect against plasma concentration curve exhibited a clear counterclockwise hysteresis, probably due to a slow naproxen transport from the circulation to its site of action. In animals with hepatitis, the protective effect remained quite constant at about 40% despite variations in plasma levels, probably because the maximal effect was reached. No clear hysteresis was observed in the effect-plasma concentration curve, suggesting that naproxen arrival to its site of action was faster. Results show that the relationship between naproxen plasma concentration and its anti-inflammatory effect is complex and therefore predictions on the pharmacological response in liver damage cannot be readily made by solely considering pharmacokinetic data.

Pharmacodynamic interaction between midazolam and a low dose of ethanol in vivo.

The pharmacokinetic and pharmacodynamic interactions between midazolam and ethanol were studied in the rat in vivo. Ethanol was given as a constant rate intravenous infusion (1.85 mg/min). The pharmacokinetics and pharmacodynamics of midazolam were determined following an intravenous dose of 5 mg/kg in 15 minutes. Amplitudes in the 11.5-30 Hz (beta) frequency band of the EEG was used as a measure of the pharmacological effect. Ethanol infusion resulted in a constant plasma alcohol concentration of 0.44 +/- 0.04 g/l (Mean +/- SE) and had no effect on the baseline value of the EEG effect parameter. Also the pharmacokinetics of midazolam were unchanged. However, a significant parallel shift of the midazolam concentration-EEG effect relationship to lower concentrations was observed. These findings show that there is a pharmacodynamic interaction between midazolam and ethanol in vivo.

Discrepancy between Bioavailability and Hypotensive Effect of Oral and Sublingual Nifedipine.

Nifedipine, 10-mg capsules, were given orally and sublingually to six healthy volunteers according to a randomized crossover design. Nifedipine plasma levels, blood pressure, and heart rate were determined at several times after medication. C(max) was higher (134 plus minus 17 vs. 93 plus minus 2 ng ml(minus sign1), mean plus minus SD, P < 0.01) and occurred earlier (0.5 vs. 1 h) with oral than with sublingual nifedipine. However, there was no significant difference in AUC (268 plus minus 56 vs. 288 plus minus 35 ng h ml(minus sign1)) nor in t(1/2) (1.8 plus minus 0.2 vs. 1.9 plus minus 0.3 h), indicating that sublingual administration decreased the rate but not the extent of nifedipine absorption. Notwithstanding the difference in C(max), both routes yielded a similar reduction in diastolic blood pressure of 13 plus minus 1 mm Hg. Heart rate increase, which reflects the activation of homeostatic mechanisms, was greater with oral than with sublingual nifedipine, that is, 18 plus minus 1 vs. 13 plus minus 1 beats min(minus sign1), P < 0.01. It is concluded that slower absorption after sublingual administration increases nifedipine hypotensive efficiency by producing less counteracting homeostatic responses than the more rapidly absorbed oral nifedipine.

Differences in nifedipine concentration-effect relationship between capsule and slow release tablet administration.

The relationships between nifedipine plasma concentrations and its hypotensive and positive chronotropic effects were studied in healthy volunteers who received either a 10 mg capsule (CAP) or a 20 mg slow release tablet (SRT). Plasma concentrations rose more rapidly after CAP than after SRT, Cmax being 131 +/- 39 and 40 +/- 7 ng/ml and tmax being 0.5 +/- 0.07 and 1.8 +/- 0.4 h, respectively. Both formulations produced a reduction in diastolic blood pressure which exhibited a significant linear correlation (p < 0.01) with nifedipine plasma concentration. However, the slope obtained with SRT was significantly higher than that of CAP (0.24 +/- 0.05 vs 0.07 +/- 0.01, p < 0.01). That is, a similar hypotensive effect was produced at a lower concentration with SRT than with CAP. A positive chronotropic effect which exhibited a highly significant correlation with nifedipine plasma concentration (p < 0.0001) was observed with CAP. Conversely, with SRT heart rate increase was smaller and there was no significant correlation with nifedipine plasma concentration (p > 0.45). Since the measured decrease in blood pressure is the outcome of nifedipine-induced vasodilation and of homeostatic responses, results are interpreted as follows. Fast nifedipine input after CAP induced a brisk change in physiological conditions and hence triggered an important homeostatic response, visualized as heart rate increase, which partially offset the hypotensive effect. With SRT, there was a gradual change in blood pressure producing lesser activation of compensatory mechanisms and therefore the hypotensive effect of nifedipine was less antagonized than with CAP. Nifedipine SRT does not only exhibit pharmacokinetic advantages, but also a more favorable pharmacodynamic profile than CAP.