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Yadira Velázquez-Armenta

Publications and source records attributed to Yadira Velázquez-Armenta.

7 recordsLinked to original sources
PubMed2005

Cyclophosphamide hypersensitivity in a leukemic child.

Although hypersensitivity reactions to chemotherapeutic drugs have rarely been reported, they may occur with any of these agents. A Mexican native 44-kg 13-year-old boy suffering from acute lymphoblastic leukemia (ALL) received chemotherapy for 7 years. Three years later, a recurrence of ALL was detected in his right testicle. The patient was scheduled to receive 12 weekly cycles of 50 mg/kg of cyclophosphamide (CPM) as a 1-hour intravenous infusion. The patient did not have any history of drug allergies or any other type of ADR. Immediately after the fourth cycle of CPM, the patient developed itchy, maculopapular rash, sweating, respiratory distress, and anxiety. According to the algorithm developed by Naranjo et al, the ADR was classified as probably secondary to CPM. Skin tests were negative to hypersensitivity to CPM, and a new cycle of CPM was administered. However, the patient developed a similar hypersensitivity reaction to CPM. After an analysis of the clinical course of the ADR and the need to continue the chemotherapeutic treatment with CPM, we decided to desensitize the patient to this drug. Total duration of the procedure was 5 hours and was performed on only 1 occasion. The program of 12 cycles of chemotherapy was successfully completed without any sign or symptom of hypersensitivity to CPM. In conclusion, we have reported a case of hypersensitivity to CPM who was successfully desensitized to CPM.

Adolescent↗
PubMed2005

Variable designs of clinical trials of neuromuscular blocking agents: an example of studies comparing rocuronium and vecuronium.

BACKGROUND: Published clinical trials on neuromuscular blocking (NMB) agents are being reported with large variations in their protocols and conflictiing results may emerge from these differences. Because they have been compared in several clinical trials, the study was focused on rocuronium and vecuronium in order to evaluate whether these NMB agents were compared under homogeneous conditions. MATERIAL/ METHOD: A search was made in PubMed, Embase Drugs and Pharmacology, Cochrane Controlled Trials Register, and Cochrane Database of Systematic Reviews. Studies on the neuromuscular response at the adductor pollicis to an i.v. bolus dose of rocuronium or vecuronium in humans were included. Quality of all reports was assessed by means of the 3-item Jadad et al. scale. Twenty-five studies met our inclusion criteria and all were retrieved. RESULTS: Randomization was performed in 21 (80.8%) studies. Blinding procedure for drug administration was mentioned in only one study without clarifying the procedure. Induction was most commonly performed with thiopental, followed by propofol. Two studies were performed in children and two in elderly patients. Withdrawals or dropouts were not mentioned in any paper. Electromyography and mechanomyography were the most common monitoring procedures. The time to maximal response, the maximum effect and the time to reach 25% recovery of neuromuscular function were the most used pharmacodynamic parameters. CONCLUSIONS: Clinical trials on neuromuscular blocking agents, e.g. vecuronium versus rocuronium, are being performed with large variability and without following established guidelines.

Adolescent↗
PubMed2004

Elimination kinetics of ethanol in pregnant women.

To evaluate the pharmacokinetics of ethanol in the early second trimester of pregnancy, ethanol concentrations simultaneously measured in the maternal blood (EtOH-MB) and in the amniotic fluid (EtOH-AF) of six pregnant women were obtained from a previous study in which a single ethanol dose of 300mgkg(-1) body weight was administered orally. For maternal blood ethanol concentration, the kinetic equation was: [Formula: see text] where k(12) and k(21) are, respectively, the rate constant of ethanol transfer from either the central compartment to the peripheral compartment or vice versa; V(max)(EtOH)is the maximal velocity for ethanol oxidation; and K(m)(EtOH) is the concentration at which half of the maximal rate of ethanol elimination is reached. The maximum concentration of EtOH in AF was 60% lower than in MB (P=0.36). However, the AUC(0-3.5h) in AF was only 16% lower than the value for MB (P=0.059). The k(12) (0.20 =/- 0.26 h(-1)) was almost twice faster than k(21) (0, h(-1)). The V(max)(EtOH) was 237.6 +/- 71.5 microgml(-1)h(-1) and K(m)(EtOH) was 3.7 +/- 4.7 microgml(-1). Our results imply that in the early second trimester, ethanol metabolism is fast. However, ethanol clearance from the AF is slower than ethanol clearance in MB. This process is widely variable, and our findings may partially explain the wide variability of ethanol's toxic effects on the fetus.

Acetaldehyde↗
PubMed2003

Mathematical analysis of a pharmacodynamic model without plasma concentrations to extend its applicability.

Using a mathematical approach, we analyzed the behavior of the PD model originally described by Bragg et al. The effect was dose-dependent modified until a maximum value (E(max)) was reached. Further increments in dose prolonged the E(max), but the recovery phase did not increase beyond a calculable asymptope. In the absence of plasma concentrations, it was impossible to distinguish the rate of plasma equilibration with the effect compartment (k(e0)) from the rate of drug elimination (k(e1)). Variations on the sigmoidicity affected both the onset and offset of drug effect. Sigmoidicity and the slowest rate constant had identical effects on the spontaneous reversion of the effect, as judged by the recovery index. The IR(50), the index of potency, merely shifted the dose-response relationship to the left or right. Changes in IR(50) were compensated for by making the same proportional changes in dose.

Blood↗
PubMedDate not supplied

Dose minimization study of oxytocin in early labor in sows: uterine activity and fetal outcome.

Two hundred sows were randomly assigned to intramuscularly receive 0.9% NaCl (group 1) or oxytocin 0.083, 0.11 or 0.17 IU/kg (groups 2, 3 and 4, respectively) immediately after the expulsion of the first piglet. The overall duration of labor was decreased in a dose-dependent relationship. Time interval between piglets was decreased approximately 5 min in groups 3 and 4 while sows in these groups exhibited approximately 10-20 contractions x 10 births more than controls (P<0.005). Duration and intensity of uterine contractions also showed a positive dose-response relationship. As an indicative of fetal distress, approximately 2.5 times more meconium-stained piglets were born to sows receiving the higher doses of oxytocin, but in the lowest dose significantly decreased. Oxytocin 0.083 IU/kg significant decreased the mortality rate of piglets [OR 0.49 (95%CI, 0.26-0.92)]. In conclusion, we recommend the intramuscular administration of the lowest possible dose of oxytocin, which still decreases the duration of labor in sows.

Animals↗
PubMedDate not supplied

Meta-analysis of the differences in the time to onset of action between rocuronium and vecuronium.

1. The aim of the present study was to conduct a meta-analysis of the magnitude of differences in the onset of action (T(max)) between rocuronium and vecuronium. 2. A search was made in PubMed, EMBASE Drugs and Pharmacology, Cochrane Controlled Trials Register and Cochrane Database on Systematic Reviews. Studies comparing the T(max) at the adductor policies between rocuronium and vecuronium administered as an intravenous bolus were included in the study. Twenty-nine effect sizes obtained from 21 studies were included. 3. The result of the meta-analysis of differences was -57.9 s (95% confidence interval -71.4 to -44.3 s), favouring rocuronium over vecuronium. The smallest difference in T(max) between these neuromuscular-blocking agents was observed in children (-19.1 s). The difference in T(max) between rocuronium and vecuronium in female patients was -38.7 s. The difference in T(max) between rocuronium and vecuronium measured by electromyography was approximately 50% shorter than that determined by acceleromyography or mechanomyography. In a subanalysis between rocuronium 600 mg/kg versus vecuronium 100 mg/kg, the difference in T(max) between them was very similar to that obtained in the general meta-analysis. 4. According to subanalyses of patient age and sex, drug dose and neuromuscular monitoring systems, the T(max) of rocuronium was approximately 20-70 s faster than that of vecuronium.

Adult↗