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Biomedical subjects

L M Lopez

Publications and source records attributed to L M Lopez.

79 records · Page 5Linked to original sources
PubMed1983

Determination of ideal body weight for drug dosage calculations.

Formulas for ideal body weight (IBW) in men and women were derived from the Metropolitan Life Insurance Company height and weight tables. Regression determinations of median weight versus height were performed for men and women. A program for a minicomputer was developed to generate plots for small, medium, and large frame sizes and for subjects of all frame sizes. Equations for ideal body weight were derived from the resulting data. For men of all frame sizes, IBW = 51.65 kg + 1.85 kg/inch of height greater than 5 feet. For women of all frame sizes, IBW = 48.67 kg + 1.65 kg/inch of height greater than 5 feet. More accurate estimates of IBW by frame size can be obtained using equations derived from the plots for men and women of each frame size. Estimates of IBW obtained by the widely used empirical method probably contain only minor errors. However, formulas derived from actual height and weight data should be used in pharmacokinetic determination of dosage regimens for some drugs.

Body Height↗
PubMed1982

Optimal lidocaine dosing in patients with myocardial infarction.

A decrease in hepatic clearance and volume of distribution in patients with congestive heart failure frequently leads to toxicity when drugs such as lidocaine are administered. To determine the effect of adjusted dosing of lidocaine in patients with myocardial infarction, we studied 32 patients receiving lidocaine either by a conventional method (control group: 1-2 mg/kg bolus, then 1 to 4 mg/min) or by an adjusted regimen based on the presence or absence of heart failure [experimental group: 1-2 mg/kg bolus; then, class I (no heart failure), 35 to 88 micrograms/kg/min; class II (heart failure), 12 to 35 micrograms/kg/min]. Plasma lidocaine levels were determined at 2 and 5 h of the infusion by enzyme multiplied immunoassay technique (EMIT) and gas liquid chromatography (GLC). Ten of 33 determinations in the control group were in the toxic range, i.e., greater than 6 micrograms/ml, and four others were subtherapeutic, i.e., less than 2 micrograms/ml. In contrast, 13 of 16 determinations in the experimental group were in the therapeutic range, and none were in the toxic range. These data show that administration of lidocaine by a conventional method may produce diverse plasma levels that may occasionally be in the toxic range. Modified dosing based on cardiac status may result in optimal levels in most patients.

Adult↗
PubMed1980

Cimetidine-induced mental status changes: case report and literature review.

An apparent case of psychosis induced by cimetidine is reported. A 61-year-old Caucasian woman was hospitalized with chief complaints of left-sided paresthesias, headache, and vertigo. She had a history of hyperparathyroidism, thyroid insufficiency, and chronic but stable renal insufficiency. Admitting laboratory data indicated possible hepatic compromise. On day 16 of hospitalization, cimetidine (300 mg q 6 hr p.o.) was begun because of a falling hematocrit and guaiac-positive stools. Within 24 hours after cimetidine therapy was begun, the patient was confused, tearful, and disoriented. This confusional state continued during treatment with cimetidine, and was refractory to antipsychotic therapy. On day 5 of cimetidine therapy, the patient experienced visual and auditory hallucinations, and both cimetidine and antipsychotic drugs were discontinued. The patient was noted to be alert and oriented 24 hours later. A review of the literature revealed 30 cases of apparent cimetidine-induced CNS changes. Patients experiencing such reactions were typically elderly with compromised renal or hepatic failure, or both. Future studies on this topic should focus on predisposing patient factors and serum or cerebrospinal fluid concentrations of cimetidine associated with the symptomology.

Adult↗
PubMedDate not supplied

Plasma lipid profiles and antihypertensive agents: effects of lisinopril, enalapril, nitrendipine, hydralazine, and hydrochlorothiazide.

Previous studies have documented potentially adverse effects of diuretics and beta-blocking agents on plasma lipid profiles. This study was designed to establish the effects on lipid profiles of the angiotensin-converting enzyme inhibitors lisinopril and enalapril, alone and in combination with hydrochlorothiazide (HCTZ), the calcium-channel blocker nitrendipine, HCTZ, and hydralazine. After a two-week, single-blind, placebo phase, 77 patients with essential hypertension were given active agent as monotherapy in a double-blind fashion for 8-20 weeks. The dose of each agent was titrated to achieve diastolic blood pressure less than 90 mm Hg. At the end of placebo and treatment phases, plasma was analyzed for triglycerides, total cholesterol, and high-(HDL), and low-density lipoprotein (LDL) cholesterol. Overall, few changes in lipid contents were noted. Total cholesterol decreased during therapy with hydralazine but increased in patients receiving the combination of lisinopril and HCTZ. HDL cholesterol was depressed in those taking HCTZ alone and in combination with lisinopril. LDL cholesterol was lowered during therapy with hydralazine but was otherwise unaffected by all other agents. None of the agents evaluated significantly affected triglyceride concentrations. Thus, monotherapy with lisinopril, enalapril, and nitrendipine do not affect plasma lipid concentrations. Hydralazine lowers total and LDL cholesterol. If these findings are confirmed in trials with larger numbers of patients, these effects on lipid profiles may influence choice of agent in the therapy of essential hypertension.

Adult↗
PubMedDate not supplied

Accuracy of serum gentamicin concentration predictions generated by a personal-computer software system.

Predictions of serum gentamicin concentration and half-life, using a personal-computer software system (SIMKIN [simulated kinetics]), were compared for accuracy as increasing amounts of patient-specific data were supplied to the computer. Data for a two-year period were collected for patients of a hospital's pharmacokinetic consultation service; the study group included adults who had at least one serum concentration for which time of last gentamicin dose was recorded. Input variables were age, weight, height, sex, serum creatinine concentration, concomitant drugs and diseases, gentamicin dosage, time of infusion, dosing interval, number of doses on each regimen, and time and reported value of all serum gentamicin concentrations. Individualized dosing regimens were calculated on the basis of literature estimates, and half-life and serum concentrations were then estimated for these regimens and compared with actual values. One or two measured serum concentrations were then added to the input data. The computer-estimated half-lives (obtained from single-point or two-point analysis in different dosage intervals) were compared with the half-lives determined from actual serum concentration data. Gentamicin serum concentrations were similarly compared. The computer's ability to predict subsequent serum concentrations improved in sequence for literature-averaged prediction and single-point and multipoint analysis. Accuracy of predicting whether peak concentrations were therapeutic or subtherapeutic and whether trough concentrations were toxic also improved as more patient-specific data were input. SIMKIN appropriately evaluated demographic and laboratory data and adequately predicted gentamicin half-lives and serum concentrations.

Adolescent↗