Re-examination of digoxin dosage regimen: comparison of the proposed nomograms or formulae in elderly patients

1 Comparison of measured trough serum digoxin concentrations (SDC) with those predicted at steady-state by forty sets of previously described pharmacokinetic equations in conjunction with either measured or estimated creatinine clearance (Clcr) was made in an elderly group of patients with varying Clcr (25-89 ml/min) who received maintenance digoxin therapy. 2 Mean values of day-to-day variation (% coefficient of variation) for serum creatine and measured Clcr examined three times within a week in 7 of 40 elderly patients were 6.42 and 8.36% respectively, while this value for SDC was 12.46%. 3 There was a statistically significant correlation (r = 0.72 to 0.79, P less than 0.001, n = 40) between measured Clcr and that estimated from three different methods. Siersbaek-Nielsen's nomogram approach gave the best correlation. 4 The calculated correlation coefficient values between measured and predicted SDC lay within a relatively narrow range but were weak (r = 0.443-0.628). Prediction error analysis, however, allowed us to determine the best set of pharmacokinetic equations for a first approximation to appropriate digoxin maintenance dosage requirements, namely Gault-estimated elimination rate constant, measured Clcr, and Jusko-estimated volume of distribution.

Isoniazid disposition, comparison of isoniazid phenotyping methods in and acetylator distribution of Japanese patients with idiopathic systemic lupus erythematosus and control subjects

1 Plasma levels of isoniazid (INH) and acetyl INH in plasma were measured with a spectrofluorometric method, and INH and its metabolites (acetyl INH, mono-acetylhydrazine, diacetylhydrazine and free hydrazine) excreted in urine were measured with a gas chromatography-mass spectrometry, respectively, after an oral dose of INH 10 mg/kg in 19 Japanese patients with idiopathic systemic lupus erythematosus (SLE) and in the same number of healthy controls. 2 When phenotyped according to various methods previously reported, 16 to 18 of the SLE and 17 to 19 of the control group were rapid acetylators. Regardless of the phenotyping methods applied, the distribution of acetylator phenotype of SLE patients was not significantly different from the control group or from the data previously reported among normal Japanese population. 3 By phenotyping our subjects with an INH T 1/2 of 110 min or less as rapid acetylators, and more slow acetylators, 3 of SLE patients and 2 of the controls were slow, while the remainder were all rapid. When this antimode was used, the mean apparent kinetic variables of INH and acetyl INH estimated from the plasma concentration-time data and the mean values for the 24-h urinary amount of INH and its metabolites, except for monoacetylhydrazine (P less than 0.05), did not significantly differ between the rapid acetylators of SLE and control groups. 4 The distribution of INH T 1/2, acetyl INH to INH ratios in plasma and urine, values in urine for log10 (diacetylhydrazine to monoacetylhydrazine) and for diacetylhydrazine to INH or acetyl INH was similar between the two groups except for one patient who was definitely classified as a slow acetylator regardless of whichever phenotyping methods were used. The excretory patterns of hydrazine compounds reflect, in general, the inactivating ability of INH in each individual. 5 The data suggest that phenotyping by using plasma samples is, in general, better than by using urine samples. The plasma T 1/2 alone is the most satisfactory criterion. 6 We conclude that neither INH disposition nor phenotype distribution assessed by the reported methods using INH as the test compound are altered in idiopathic SLE, and that a search for racial and/or geographical factor(s) likely to result in autoimmune disease may give a clue to the pathogenesis in addition to further exploration for the possible interrelation between idiopathic SLE and genetic slow acetylation.

Toxic haloperidol reactions with observation of serum haloperidol concentration in two children

In 2 children who accidentally received haloperidol (0.26 mg/kg in one and 0.10 mg/kg in another) from a prescription error, haloperidol concentrations in serum in both cases and in cerebrospinal fluid in one case were measured with the radioimmunoassay method during the development of the toxic drug reactions. The serum haloperidol concentrations in both cases were far beyond the proposed therapeutic range in children. Our cases are generally compatible with previous findings of others and indicate that the intensity and/or incidence of toxic reactions of haloperidol may be related to plasma concentrations.

Individualized aminophylline therapy in patients with obstructive airway disease: oral dosage prediction from an intravenous test dose

Theophylline disposition after an intravenous test dose of aminophylline was determined in 83 subjects: 7 patients with and 58 without congestive heart failure (CHF), and 18 healthy controls. Based on the pharmacokinetics of theophylline in the individual, the oral dosage of aminophylline was scheduled to attain steady-state trough theophylline concentrations (Cpred) near the therapeutic margin. Significant differences in theophylline clearance with a relatively constant volume of distribution were observed between various groups divided by age, smoking habit and CHF; the significantly different (p less than 0.001) mean clearance values were: 0.042 +/- 0.016 l/h/kg (mean +/- SD) in patients without CHF (n = 58) as opposed to 0.016 +/- 0.001 l/h/kg in patients with CHF (n = 7), 0.038 +/- 0.013 l/h/kg in non-smokers (n = 59) versus 0.054 +/- 0.015 l/h/kg in smoking subjects (n = 17), and 0.030 +/- 0.010 l/h/kg in elderly (greater than 60 years) non-smoking patients (n = 7) versus 0.057 +/- 0.017 l/h/kg in smoking patients (n = 5) aged 40 to 59 years. No gender-related difference was detected in theophylline disposition. For all subjects together (n = 83), there was no significant correlation between age and clearance (r = -0.111, p greater than 0.1). The multivariate analysis indicated that the overall variability in theophylline clearance was affected first by the smoking habit (t = 4.960; p less than 0.001) and second by CHF (t = -3.052; p less than 0.001), but not by age (t = 1.140) or by sex (t = 0.069). 78% of the patients who did not have CHF required a daily dose of aminophylline of 600 to 900 mg, whereas a dose of 300 to 450 mg was the rule in patients with CHF. The measured steady-state minimum concentration (Cmeas) ranged from 5.4 to 14.6 micrograms/ml (9.0 +/- 2.2 micrograms/ml: mean +/- SD) which was in good agreement with the Cpred (5.6 to 13.6, 9.0 +/- 1.6 micrograms/ml) in all patients (n = 60) who received the oral dose of aminophylline calculated from the test dose. The overall prediction error was -0.08 +/- 1.83 micrograms/ml (-1.42 +/- 19.90%); only 3 of 60 measurements were found to be outside +/- 2 SD. It is concluded that using a test dose to individualize aminophylline therapy is likely to remain the most reliable means to assure the maximum therapeutic benefit in patients with airway obstruction.

Acetylator phenotype and metabolic disposition of isoniazid in Japanese patients with systemic lupus erythematosus

Acetylator phenotype and metabolic disposition of isoniazid (INH) were studied in 19 Japanese (a population shown to be 11.5% slow acetylators) patients with spontaneous systemic lupus erythematosus (SLE) and 19 healthy controls. Subjects with the elimination half-life (t1/2) of INH of 2.0 hours or less were considered rapid and those of 2.2 hours or more were slow acetylators. Results of phenotyping showed that 17 of 19 SLE patients were rapid, 1 slow, and 1 indeterminate, whereas 18 of the controls were rapid and 1 indeterminate. When phenotyped according to another reported antimode (107 or 110 minutes), 3 of the patients and 2 of the controls were slow and the remainder were all rapid acetylators. The distribution of INH t1/2, acetyl INH to INH ratios in urine and plasma, and hydrazine compounds in urine measured with gas chromatography mass spectrometry was similar between the two groups, except for 1 patient who was definitely classified as a slow acetylator. The relationship between phenotype distribution and possible pathoetiologic factors is discussed.

Pharmacokinetics of ketoprofen following single oral, intramuscular and rectal doses and after repeated oral administration

The pharmacokinetics of ketoprofen was studied in the same healthy subjects after single oral, intramuscular and rectal doses, and after repeated oral administration. No significant difference in the mean t1/2 (1.13-1.27 h) was observed after the different modes of administration. The mean [AUC] 0 infinity after rectal administration of a suppository showed the minimum significant difference (p < 0.05) from that after oral administration of the capsule. The apparent volume of distribution (Vd/F) was approximately 10-15% of body weight. The renal contribution (mean, 0.10-0.15 ml/min/kg) to the plasma clearance of free ketoprofen was assumed to be, at most, 8.3-12.9%. The projected cumulative excretion of total (free plus conjugated) ketoprofen via urine exceeded 63-75% of the dose, of which approximately 90% was ketoprofen glucuronide. A mean of 71-96% and 73-93% of the oral capsule was estimated to be systemically available after administration of the intramuscular preparation and rectal suppository, respectively. In four of seven subjects, CPK concentration was elevated after the intramuscular injection. The mean steady-state concentration of ketoprofen in plasma ranged from 0.43 to 5.62 microgram/ml after the final dose of a 50 mg q. i. d. regimen. The disposition data and plasma levels observed at steady-state were in agreement with those predicted from the single oral dose study. The accumulation ratio was 1.08 +/- 0.08. The results suggest that the rectal suppository can be recommended as an extravascular mode of administration of this drug.

Pharmacokinetic studies with dibekacin, a new aminoglycoside, after intravenous and intramuscular administration to human volunteers

The pharmacokinetics of dibekacin, a new aminoglycoside antibiotic, was studied in volunteers given the same dose (100 mg) intramuscularly on two separate occasions and intravenously at two different rates of infusion. The kinetic parameters (t 1/2, 2.24 h, and Vd, 0.136 liter/kg, as the overall mean) observed after intramuscular administration appear to be compatible with those of other aminoglycosides and fairly reproducible within the same individuals. Dibekacin was rapidly absorbed (tmax, 0.84 h), yielding a peak level of 10.4 microgram/ml after the 100-mg intramuscular dose. After the 30- or 60-min infusion, the concentrations of dibekacin in serum fell bi-exponentially, giving an elimination half-life (t 1/2 beta) of 2.50 to 2.88 h. The highest serum levels after th 30- and 60-min infusions were 15.2 +/- 0.9 and 12.1 +/- 1.8 microgram/ml, respectively. Serum levels at 6 h after completion of infusions were 1.9 +/- 0.3 and 1.7 +/- 0.4 microgram/ml, respectively.

No enhanced elimination of propranolol in patients with hyperthyroidism

Propranolol, a widely used beta-adrenergic receptor blocking drug extracted mostly by the liver, plays an important role in the various aspects of managment of hyperthyroidism. If the elimination of this drug is enhanced in thyrotoxic patients, one may consider necessary a modification of the dosage regimien when treating patients with this dysfunction. We examined the disposition profiles of propranolol in four patients with hyperthyroidism before and after their thyroid states became euthyroid and compared them to those of the seven control subjects. The data indicated that the values (mean +/- SEM) of half-life (3.34 +/- 0.81 hr) and systemic availability estimated (28.2 +/- 3.5%) in the hyperthyroid state were comparable to those in the euthyroid state (2.98 +/- 0.32 hr and 29.2 +/- 5.1%) and these in the control subjects (3.20 +/- 0.32 hr and 29.0 +/- 4.0%). Although our observations were obtained from a small number of subjects, there appears to be no considerable difference in propranolol elimination from the plasma of hyperthyroid and euthyroid states or healthy subjects, and therefore adjustment of the dosage regimen seems unwarranted. Adjustment of propranolol therapy based on individual plasma levels might be useful in thyrotoxic patients who respond inadequately until additional data relating more precisely to propranolol disposition becomes available.

[A case of 17 alpha-hydroxylase deficiency with male pseudohermaphroditism (author's transl)]

A 17-year-old youth was admitted because of proteinuria noted during a routine examination at his high school. His parents and three siblings were living in good health and there was no familial tendency to hypertension and no consanguinity. On physical examination, he was 161cm in height and weighed 43Kg, and his facial expression was female-like. Neither webbed neck nor cubitus valgus was noticed. Severe hypertension ranging from 190/120 to 230/130 was noted. No axillary or pubic hair was present, and the breasts were prepubertal in size. A gynecological examination revealed the presence of labia and vagina. Laboratory findings on admission were summarized as follows: The urine gave a (-)--(+) test for protein, renal function was revealed as normal, serum potassium ranged from 3.2 to 4.2mEq/L, the specimen of arterial blood showed pH 7.421, and an electrocardiogram revealed left ventricular hypertrophy and U wave changes in leads V2, V3, V4. X-rays showed a bone age of 12 years, and chromosome analysis revealed a karyo type of 46,XY. Endocrinological studies confirming the presence of a 17 alpha-hydroxylase deficiency were summarized as follows: 1) Plasma ACTH was markedly elevated. 2) Plasma renin activity was markedly suppressed showing no response to exercise. 3) Plasma progesteron, plasma DOC and plasma-corticosteron were extremely high. In contrast, plasma aldosteron was extremely low. 4) Plasma 17 alpha-OH progesteron and plasma cortisol were markedly reduced. Urinary excretion of 17-OHCS was extremely low. 5) Plasma testosteron and urinary 17-KS were markedly reduced. The patient was treated with 2mg then 1mg dexamethasone daily for half a year. After one month of therapy, the blood pressure was down to 160/100mmHg, and the serum potassium had risen from 3.2mEq/liter to 5.6mEq/liter. Plasma progesteron, plasma DOC, plasma corticosteron and plasma ACTH decreased to a normal level. Subsequently suppressed plasma renin activity elevated to a normal value. After 6 weeks of this treatment, a laparotomy was performed. Ovaries and uterus were absent, but bilateral testes were found at the external inguinal ring. Microscopic examination of the testis showed Sertoli cell adenoma. We have reported here a case of 17 alpha-hydroxylase deficiency with male pseudohermaphoriditism and discussed the endocrinological data and histological findings of the testis.

Michaelis-Menten pharmacokinetics of diphenylhydantoin and application in the pediatric age patient

Michaelis-Menten pharmacokinetics were evaluated for diphenylhydantoin given to 104 patients 0.5 to 16 years of age with seizures. A method for individualizing the dosage regimen of DPH for each patient was evaluated retrospectively. The Vmax was inversely related to age (r = 0.552, P less than 0.001) but there was no such relationship for Km. The individual pharmacokinetics were characteristic of that person and could be used to adjust dosage so that toxicity would be avoided. We present a nomogram for adjusting the dosage of DPH in the pediatric age groups.

Likely explanation for longer duration of pharmacological (antianginal) effects of propranolol in relation to its short half-life

Plasma propranolol concentration-effect-time data obtained from the literature were analyzed by applying a theory for correlating the observed kinetic data with the pharmacological (antianginal) effects using the elimination rate constant (Kel) and the slope of log concentration-effect relationship (m). The plasma propranolol concentrations yield the first-order rate elimination while the drug effects decline linerarly with time at the zero-order rate as proposed by the theory. The rate of decline of drug effects derived from the application of the theory ("theoretical" Rd) was found to be in reasonable agreement with that actually observed in the effect-time interrelations ("observed" Rd), which will imply that the longer duration of the antianginal effects of propranolol is explainable with its short half-life.

Absence of changes in drug disposition and catecholamine sensitivity in the hyperthyroid dog

1 In order to study the relative contribution of hepatic drug metabolizing enzymes and hepatic blood flow to the clearance of drugs in the hyperthyroid state, the disposition kinetics of two model compounds (antipyrine and propranolol) were examined in thyroid-fed dogs as compared to euthyroid and phenobarbitone-pretreated animals. 2 In hyperthyroid dogs, the possibility of catecholamine hypersensitivity was evaluated by assessing the chronotropic response to isoprenaline and by constructing a drug concentration-effect (beta-blockade) relationship. 3 The plasma propranolol half-life (0.97 +/- 0.12 h) of the hyperthyroid animals did not differ significantly from either the euthyroid group or the phenobarbitone-pretreated group. This was observed with no significant change in the apparent volume of distribution among the three experimental groups. 4 Phenobarbitone pretreatment accelerated significantly the elimination of antipyrine (half-life, 1.09 +/- 0.15 h, P less than 0.01) as compared to the euthyroid (2.84 +/- 0.35 h) and the hyperthyroid groups (2.58 +/- 0.13 h), respectively, without any changes in the apparent volume of distribution in any group. 5 Neither the chronotropic responses to exogenously administered catecholamine, nor the antagonist concentration-effect relationships support the concept that the hyperthyroid state potentiates sensitivity of the receptor-effect system of the heart. 6 The data obtained from the present study fit best with the view that thyroid hormone excess alters neither the disposition of the model compounds used nor the catecholamine-sensitivity examined.

Relationship between pharmacokinetics and pharmacodynamics of the beta adrenergic blocking drug sotalol in dogs

The relationship between pharmacokinetics and pharmacodynamics was studied in dogs using sotalol as a model. The t 1/2 of this drug (4.30 +/- 0.40 hr) in dogs was longer than that of other beta adrenergic blockers. The renal clearance of the drug (4.21 +/- 0.31 ml/min/kg) was approximately 90% of total plasma clearance together with an extensive fraction excreted unchanged (72 +/- 12% of dose) in urine. Significant beta blockade, assessed by the response to isoproterenol tachycardia, was observed without change in blood pressure during the experiments. The log plasma sotalol concentration correlated significantly with the beta blockade (P less than .001). In an attempt to obtain insight into drug concentration-effect-time data, we applied a theory for correlating the observed kinetic data with the pharmacological effects using the elimination rate constant (beta) and the slope of log concentration-effect relationship (m). The rate of decline of drug effects (Rd) derived from this application agreed well with that actually observed in the effect-time interrelations.

Pharmacokinetics of piroxicam, a new nonsteroidal anti-inflammatory agent, under fasting and postprandial states in man

The kinetic disposition of piroxicam, under evaluation in man as a new anti-inflammatory drug, was studied in human volunteers given a single oral dose after both overnight fasting and food. Total absorption was uninfluenced by food intake, although the data indicate that food causes some delay in attainment of peak serum levels. The half-life of drug in plasma in the fasting subjects (37.5 +/- 2.4 hr) was similar in both the fasting state and after food, suggesting that once-daily dosing may be appropriate for maintaining therapeutic plasma levels. Mean pharmacokinetic parameters for both studies in the fasting state and after meals are volume of distribution divided by availability, 0.140 or 0.136 liter/kg; total plasma clearance divided by availability, 2.68 or 3.12 ml/hr/kg. Approximately 10% of a single dose of piroxicam was eliminated in the urine within 8 days after oral drug administration. Renal clearance of the drug (0.28 +/- 0.10 ml/hr/kg) was 10.4% or less of plasma clearance, suggesting that piroxicam is extensively metabolized. In this study one subject showed a reduction in white blood count on the sixteenth day after a 60-mg dose; however, hematology values evaluated in both intra- and intersubject comparisons did not show any other differences in the present study.

The effect of assay methods on plasma levels and pharmacokinetics of theophylline: HPLC and EIA

1 The effects of two assay methods, HPLC and EIA, on theophylline plasma levels (n = 254) and pharmacokinetics (n = 6) were examined on blood samples obtained from asthmatic patients and normal adult male volunteers. 2 The standard curves obtained and the plasma level values during plasma level monitoring of theophylline measured with two methods are well correlated each other within concentration range of 2.5 to 20.0 microgram/ml (P less than 0.001). EIA, however in general, appears to give a lower value than HPLC. 3 The values of plasma theophylline half-life and clearance analyzed using a two-compartment open system model were found different between the two assay methods and dissimilar to those previously reported by using ultraviolet method. 4 The sampling end-point and/or assay sensitivity particularly to measure a lower level of theophylline (less than 2.5 microgram/ml) can influence the pharmacokinetics for a potent bronchodilator with a narrow therapeutic margin, theophylline.

[Epidemiological studies on the symptoms due to strawberry culture in the vinyl-house. 2. An analysis of clinical examinations with emphasis on allergic response (author's transl)]

Clinical mass surveys were carried out on the residents to whom questionnaires on symptoms with reference to strawberry culture in the vinyl-house had been delivered. Two hundred and eleven persons attended at the first survey in September, 1976 (off the season of strawberry culture) and the 58 attended at the second survey in March, 1977 (within the season). The participants of the first survey consisted of three groups, i.e. farmers with and without strawberry culture and people without farming. The participants of the second survey consisted only of farmers with strawberry culture. Results are summarized as follows. 1) There were no difference of incidence of various clinical findings detected by an ophthalmologist and otolaryngologists among the three groups. 2) There were also no difference of incidence of abnormal findings in urine tests, liver functions, respiratory test, blood examinations and blood pressure test among the three groups. However, the comparison of persons in charge of strawberry culture and attended at both tof the first and the second surveys, such changes were detected as increases in the value of GOT (within normal limits), of stab neutrophiles, lymphocytes and of monocytes within the season of strawberry culture. 3) Increases of positive rates in skintest by extracts of house dust and Candida sp. were observed in the farmers with and without strawberry culture. Positive rates of skintest by strawberry pollen and honey bee extracts among the farmers with strawberry culture were markedly higher than the allergic patients in Dokkyo Hospital having no relation to this culture. This positive rate was markedly elevated among the persons who complained the symptom of rhinorrea within the season.

Pharmacokinetic differences between single and multiple oral dosing with the guidance for beta-adrenoceptor blockade assessment

The disposition profiles of a new beta-adrenergic-blocking drug, timolol, were investigated in healthy subjects after single oral doses, and in patients with mild or moderate essential hypertension given multiple doses. The t1/2 of timolol were different between the two groups, possibly due to the decreased plasma clearance after multiple administration. The dosage regimen calculations for patients indicated to receive the treatment for certain chronic diseases, should be determined by utilizing the disposition data obtained in steady-state conditions. The absolute reduction of exercise heart rate gave the best coefficient as a beta-blockade assessment. Applying a theory for translating the pharmacokinetics to the duration-action course of drug, pharmacokinetic t1/2 was proven to be much shorter than pharmacological t1/2. Timolol given on a twice-daily schedule has shown both antihypertensive effectiveness and plasma-renin-suppressing action in different subject. However, the casual relationship between the drug plasma level, blood pressure fall and change in PRA was not so clearly disclosed. The pharmacokinetics of beta-blockers, particularly with the property of receiving extensive metabolism by the mechanism of hepatic first-pass effect should be studied between single- and multiple-dosing schedules in subjects with diverse clinical conditions.

Double-blind studies of tolerance to praziquantel in Japanese patients with Schistosoma japonicum infections

The first clinical trials of praziquantel against Schistosoma japonicum infections in Japan were planned to assess tolerance only. Three double-blind studies against placebo involving a total of 51 patients were conducted with dosages of praziquantel of 1 x 20 mg/kg body weight, 2 x 20 mg/kg, 3 x 20 mg/kg given on one day.The frequency of unwanted side effects was higher in the group of patients given praziquantel at a dose of 3 x 20 mg/kg than in all other drug- or placebo-treated patients. In general, the side effects, which included drowsiness, headache, lumbago, abdominal fullness, or epigastric discomfort, lasted for several hours but disappeared spontaneously. The results of laboratory tests showed no significant changes caused by treatment.The overall assessment showed excellent or good tolerance in all patients treated with praziquantel at the lower dose levels. In those given 3 x 20 mg/kg, tolerance was excellent in 1 of 12 patients, good in 9, and fair in 2, whereas the respective placebo-treated group showed excellent tolerance in 3 of 12, good in 7, and fair in 2.

Comparison of disposition and effect of timolol and propranolol on exercise tachycardia

The kinetic disposition and beta-adrenergic blocking action in relation to plasma level of a single oral dose of either timolol or propranolol has been compared in healthy male volunteers. The disposition profiles clearly disclosed different properties of the two drugs, although their half-lives were similar. The available fraction of timolol in the systemic circulation was estimated to be approximately 60% of the dose, and 17.4% was exereted unchanged in urine. The logarithm of plasma concentration showed a significant correlation with the beta-blocking activity assessed by an exercise test. The mean potency ratios of timolol to propranolol as an antagonist of chronotropic effects on exercise tachycardia were 11 to 17 and 3.6 to 5.5 in dose- and concentration-effect relationships, respectively. The absolute reduction of exercise heart rate gave the best coefficient of all measures of beta-blockade. When drug action was measured as beta-blockade assessed by a given response to exercise tachycardia, the effect declined linearly with time, even though plasma levels fell exponentially. This results suggest that the pharmacokinetic t1/2 is much shorter than the pharmacological t1/2.

Clinical pharmacologic observations on timolol. I. Disposition and effect in relation to plasma level in normal individuals

The disposition profiles of a new beta-adrenergic blocking drug, timolol, were investigated at 11 different times in normal individuals after a single oral dose. The disposition of timolol follows first-order kinetics and may be adequately described by a one-compartment model. The pharmacokinetic data were not significantly different among the three dose levels examined. After the single oral doses, overall elimination half-life was 3.2 +/- 0.2 hours (mean +/- S.E.M.), with an observed peak time of 2.0 +/- 0.2 hours; extrapolated volume of distribution was 1.81 +/- 0.15 liter/kg; and the total plasma clearance was 557 +/- 61 ml/min. Approximately 20 per cent of elimination from the human body was dependent on the kidney. The area under the curve from zero to infinity and the peak concentration observed were dose dependent. A linear relationship was found between timolol plasma concentrations and beta-adrenergic blocking effects (per cent inhibition), as estimated from exercise-induced tachycardia. Timolol is a beta blocker which must await further clinical trials for the assessment of therapeutic implications in relation to plasma levels.

Clinical pharmacologic observations on timolol. II. Antihypertensive effect and kinetic disposition on twice-daily dosing in patients with mild or moderate hypertension

Timolol given on a twice-daily schedule has shown both antihypertensive effectiveness and plasma renin-suppressing action in eight patients with mild or moderate hypertension. However, the causal relationship between the drug plasma level, blood pressure fall, and change in plasma renin activity was not so clearly demonstrated in the present study. The disposition profiles of timolol at the steady state show an elimination half-life of 4.7 +/- 0.7 hours and a total plasma clearance of 225 +/- 21 ml/min. These values are found to be different from those of our previous observations obtained in normal individuals. Although the range of mean timolol concentrations at steady state varies to a certain extent among different patients, the dosage regimens for patients who will receive treatment for certain chronic disease states (e.g., arrythmias, obstructive cardiomyopathy, and angina pectoris, but not hypertension) in relation to plasma levels should be based on the disposition data obtained under steady state conditions. Bronchospasm developed in one of eight patients whose timolol level was found to be higher than the average of other patients given the same dosage.

Hemodynamic effects of systemic and central administration of alpha-methyldopa

Systemic and regional hemodynamic changes were measured in five restained conscious rhesus monkeys before and after a 2-hour intravenous infusion of 50 mg/kg of alpha-methyldopa and, in another group of five monkeys, 5 to 10 mg injected into a lateral cerebral ventricle. Both routes of administration evoked similar degrees of hypotension, bradycardia and decreased cardiac output, although the cerebral intraventricular (i.c.v.) injections had more immediate and long-lasting effects. Both groups had a similar pattern of changes in the redistribution of cardiac output and blood flow that lasted at least 4 hours. Blood flow was maintained in the hepatic and renal arteries and decreased in skeletal muscle, heart, brain and skin. In contrast, i.c.v. injections of alpha-methyldopamine and alpha-methylnorepinephrine given at the same site evoked dose-related pressor responses that lasted up to 4 hours. The data suggest that alpha-methyldopa has important central action that inhibits sympathetic outflow, but that its hypotensive effect is either mediated only by endogenously formed metabolites or that its mechanism of action is not directly related to these metabolites at sites around the lateral and third cerebral ventricles in the monkey.

Suppressing effects of purified eosinophils derived from guinea pigs sensitized with Ascaris antigen on lymphocyte-blastformation

Highly purified eosinophil (EOS) fractions were obtained from peritoneal exudate cells of guinea pigs immunized with with Ascaris lumbricoides suum antigen (Asc). These Eos suppressed the in vitro DNA synthesis of the lymph node cells (LNC) sensitized with Asc and then activated by this antigen or phytohemagglutinin (PHA). Although addition of Eos did not effect the viability of LNC in vitro, the blastformation of LNC was suppressed remarkably when 5-10 X 10(5) purified Eos were added to 10(6) LNC within 48 hr after the start of stimulation by Asc. The suppressive effects of Eos on the blastformation of LNC immunized with complete Freund's adjuvant with or without ovalbumin were observed when stimulated with purified protein derivates or ovalbumin. Such suppression were observed beyond the barrier of animal strain specificity; Eos from Hartley guinea pigs suppressed proliferation of LNC from either strain 13 or strain 2, and Eos from strain 13 suppressed that from strain 2. Such suppressing activity of Eos was reduced by heating them at 56 C for 1 hr or by sonication.

Physical fitness of children aged 5 and 6 years

Maximal oxygen uptake (Vo2 max) of 85 healthy kindergarten children, 46 boys and 39 girls, aged 5 and 6 years, was determined by means of track running. Their physique, skinfold thickness, grip and back muscle strength, and performances of 25 m-run, 50 m-run, standing broad jump, and 5 min-endurance run were also measured. Skinfold thickness of girls was significantly larger than that of boys. Boys were significantly superior to girls in all the motor performances. The Vo2 max per unit of body weight was 49.46 ml/kg/min for boys and 46.30 ml/kg/min for girls, the sex difference being significant at the 0.001 level. The correlation coefficient between Vo2 max per kg body weight and 5 min-endurance run performance was 0.417 for boys and 0.049 for girls, while that between absolute Vo2 max and body weight was 0.899 for boys and 0.563 for girls. The regression equation of the absolute value of Vo2 max (liter/min) on body weight (kg) was: Y=0.051X-0.025 for boys and Y=0.024 + 0.408 for girls, the regression coefficient of boys being twice as large as that of girls. It appears that at ages 5-6 sex differences are exhibited ont only in muscle strength and agility but also in endurance run and aerobic work capacity.