Sublingual captopril — a pharmacokinetic and pharmacodynamic evaluation

Summary In this study we compared the pharmacokinetics and pharmacodynamics of captopril after sublingual and peroral administration. Single 25 mg doses of captopril were administered sublingually and perorally on two different occasions in a randomised cross-over fashion to eight healthy volunteers aged 22–35 years. The kinetics of unchanged captopril, plasma renin activity (PRA), BP and heart rate were studied over three hours after both peroral and sublingual administration of captopril.Mean pharmacokinetic parameters for unchanged captopril after sublingual administration were: C_max, 234 ng·ml^–1; t_max, 45 min; AUC (0–3 h), 15.1 g·ml^–1. min. Mean pharmacokinetic parameters for unchanged captopril after peroral administration were: C_max, 228 ng·ml^–1; t_max, 75 min; AUC (0–3 h), 17.0 g·ml^–1. min. t_max was significantly shorter when captopril was administered sublingually; all other pharmacokinetic parameters were equivalent.The plasma captopril concentrations achieved post drug administration led to increases in PRA and reductions in BP. t_max for PRA was 86 min for sublingual captopril and 113 min for perorally administered drug. Peak PRA values were, however, not significantly different. BP, as expected, was not reduced dramatically in these healthy volunteer subjects, however, in systolic BP vs time profiles, BP was significantly lower after volunteers received sublingual captopril. Heart rate increased slightly after captopril administration; there were no differences between the two routes of administration. Administration of captopril sublingually, therefore led to a more rapid attainment of plasma captopril concentrations and had a more rapid onset of pharmacological effect when compared with peroral administration.     

Pharmacokinetics of oral salbutamol controlled-release in Asian patients with asthma

Summary Using a double blind, double dummy crossover design, single dose and steady state pharmacokinetics of oral controlled release (SCR) salbutamol 4 mg and 8 mg tablets b. d. has been studied in 8 Asian patients.Plasma salbutamol was measured over 12 h. In 8 patients the single dose mean C_max was 4.2 ng·ml^–1 and 7.7 ng·ml^–1 after 4 and 8 mg, respectively. In 5 patients the steady state mean C_max, C_min and t_max were 8.1 ng·ml^–1 and 4.7 ng·ml^–1 and 6 h for the 4 mg tablets and 14.1 ng·ml^–1 and 7.1 ng·ml^–1 and 4 h for the 8 mg tablets.It is concluded that both doses of SCR show features of controlled release and that they produced a relatively constant plasma level of salbutamol in Asian patients.     

Interaction of talinolol and sulfasalazine in the human gastrointestinal tract

Summary The absorption of talinolol (TA) 50 mg was investigated without and together with the co-administration of sulfasalazine (SASP) 4 g in 11 healthy young volunteers, in order to clarify gastrointestinal transit of TA.Without SASP, the t_max of TA was 2.8 h, C_max was 112 ng·ml^–1 and the half life was 12 h; the AUC_o-t was 958 ng·ml^–1·h.In the case of concomitant administration of SASP, TA was found only in serum from 3 individuals, with a C_max of 23 ng·ml^–1 and a mean AUC_o-t of 84 ng·ml^–1·h. TA was not detectable in 5 subjects and it was at the limit of detection (2 ng·ml^–1) in 3 subjects. Pharmacokinetic analysis was not possible in any of those individuals.The reason for the interaction appears to be the adsorption of TA by SASP. An interval of 2–3 h should elapse between giving SASP and other drugs.     

A pharmacokinetic and pharmacodynamic evaluation of buffered sublingual captopril in patients with congestive heart failure

Objective: The pharmacokinetics and pharmacodynamics of buffered sublingual captopril were assessed in patients with congestive heart failure (CHF). Methods: The study was carried out in a randomised single-blind cross-over fashion (n=6, 4 males and 2 females) and involved two study days, at least 7 days apart. Baseline measurements were carried out for plasma renin activity (PRA), blood pressure (B.P.) and heart rate (H.R.). Captopril (12.5 mg) was administered sublingually with dibasic potassium phosphate which maintained salivary pH at 7, or perorally with 100 ml of water. Further B.P., H.R. measurements and venous blood samples were taken over a 3 hour period post-drug administration. Blood samples were analysed for captopril and PRA levels. Results: t_max after buffered sublingual administration of captopril, which ranged from 40–60 min (median=40 min), was significantly shorter than after peroral administration (range 60–120 min, median=90 min). C_max was slightly greater after buffered sublingual than after peroral administration with mean values of 108.2 vs. 94.0 ng·ml^–1. AUC values were similar after both routes of administration. Systolic and diastolic B.P. vs. time profiles for each administration method were significantly different i.e. sublingual administration produced an earlier reduction in B.P., however, HR did not differ significantly between the two routes. Conclusion: The data indicate that this novel administration method of captopril leads to an increased rate, but an unchanged extent of captopril absorption, suggesting a modest therapeutic advantage with the use of buffered sublingual captopril if a rapid reduction in blood pressure is required.     

Pharmacokinetics of intravenous and oral isosorbide-5-mononitrate

Summary The pharmacokinetics of isosorbide-5-mononitrate (IS-5-MN) has been studied in two groups of healthy volunteers after oral (n=20) and intravenous (n=11) administration of 20 mg, which had previously been proved to be as effective as 20 mg sustained-release isosorbide dinitrate (ISDN). IS-5-MN in serum was measured by gas chromatography using capillary columns. The kinetic calculations were carried out with a newly developed model, which assumes a virtual volume of distribution dependent on time. IS-5-MN is rapidly (invasion half-life 4.1 min) and completely absorbed from the gastro-intestinal tract without any first pass metabolism. The maximum concentration of 480 µg/l was reached 1.2 h after oral administration of 20 mg. The substance was distributed throughout the total body water (distribution coefficient: 0.62), and was eliminated with a terminal t_1/2 of 4.1 and 4.6 h after oral and intravenous administration, respectively. Total body clearance was 115 ml/min. Thus, IS-5-MN is unlike ISDN with respect to the absence of first-pass metabolism and an 8-times longer half-life. The consequences for therapy are discussed.     

Differences in the nitrite ion formation and the toxicological findings between isosorbide dinitrate and isosorbide-5-mononitrate

In the metabolism of isosorbide dinitrate (ISDN), fast denitration with the formation of nitrite ions and a mononitrate plays an important role. In contrast, the denitration of isosorbide-5-mononitrate (IS-5-MN) to isosorbide is very slow. Accordingly po administration of high doses of ISDN (92.5 and 236 mg/kg) in conscious dogs led to maximum nitrite concentrations in the blood of 0.9 and 3.3 mg/liter, respectively. In contrast, with equimolar doses of IS-5-MN (75 and 191 mg/kg) we were able to detect nitrite ions reliably only at the higher dose and this gave a maximum blood concentration of 0.4 mg/liter. The rise in nitrite ion concentration is followed by the formation of methemoglobin. As is known from the literature, there is a rise in the activity of alkaline phosphatase in the serum of rabbits in addition to methemoglobin formation following repeated administration of sodium nitrite. So we have specifically investigated whether this is also the case following ISDN and IS-5-MN administration. On po administration of 236 mg/kg ISDN/day to dogs, there was a continuous rise in alkaline phosphatase from about the 20th day onward which we did not observe after the equimolar dose of IS-5-MN (191 mg/kg). NaNO₂, 35 mg/kg po, led to a comparable maximal rise in methemoglobin to that obtained with 236 mg/kg ISDN. Repeated po administration of 35 mg/kg NaNO₂/day also caused a rise in alkaline phosphatase. It is concluded that the formation of nitrite ions from ISDN is the reason for the rise in methemoglobin and alkaline phosphatase. The lower formation of nitrite ions from IS-5-MN can also be of clinical importance, at least in certain cases.     

Cutaneous metabolism of isosorbide dinitrate after transdermal administration in isolated perfused porcine skin

The purpose of this study was to determine whether isosorbide dinitrate (ISDN) was metabolized by the skin during transdermal delivery. In order to assess this, the isolated perfused porcine skin flap (IPPSF) was utilized since this in vitro model possesses a viable epidermis and intact vasculature, two attributes ideal for studying the biotransformation of a vasoactive drug. ISDN transdermal systems (20 cm²) were applied onto IPPSFs and the venous efflux sampled repeatedly over 16 h. ISDN, isosorbide-2-mononitrate (IS-2-MN), and isosorbide-5-mononitrate (IS-5-MN) fluxes were determined using gas chromatography. Approximately 14% of parent ISDN was metabolized to IS-2-MN and 10% to IS-5-MN. These observations are important as they indicate that a fraction of ISDN is biotransformed during transdermal delivery.     

Bioavailability and bioequivalence of organic nitrates. Isosorbide dinitrate--a study of sustained-release preparations

Assessment of Bioavailability of Organic Nitrates/Comparative bioavailability study of sustained-release isosorbide dinitrate preparations. Relative bioavailabilities of isosorbide dinitrate (ISDN, CAS 87-33-2) and the metabolite isosorbide-5-mononitrate (IS-5-MN, CAS 16051-77-7) were studied after application of Maycor retard 40 (sustained-release capsules, multiple unit formulation, test preparation) in comparison to sustained-release tablets (single unit formulation, reference preparation) with 16 healthy male volunteers in a two-way crossover design. Test and reference formulations were previously characterised in vitro by dissolution tests. ISDN, IS-5-MN (IS-2-MN) plasma concentrations were determined using a selective and sensitive GLC-method with ECD-detection. As pharmacokinetic parameters AUC, Cmax and half value duration (HVD) were evaluated. Bioequivalence was assessed by calculating 90%-confidence intervals (ANOVA, ANOVAlog, Mann-Whitney-test) for ISDN and IS-5-MN. Bioequivalence was accepted if due to the inclusion rule one of the calculated intervals fulfill the requirements of 80 and 120% (AUC) or 70 and 130% (Cmax, HVD), respectively. Relative bioavailability of the test formulation was calculated as 94% (ISDN) and 96% (IS-5-MN). Maximum plasma concentrations of ISDN (IS-5-MN) were determined for the test preparation as 14.3 +/- 3.1 ng/ml (265 +/- 45 45 ng/ml) and as 22.8 +/- 12.6 ng/ml (287 +/- 59 ng/ml) for the reference product. HVD-values were for the test preparation 4.5 +/- 1.3 h (ISDN) and 8.5 +/- 1.3 h (IS-5-MN) and for the reference formulation 3.1 +/- 1.2 h (ISDN) and 8.1 +/- 1.4 (IS-5-MN).(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical chronopharmacology of oral sustained-release isosorbide-5-mononitrate in healthy subjects

Summary In 10 healthy male subjects the pharmacokinetics and haemodynamic effects of sustained-release isosorbide-5-mononitrate 60 mg (IS-5-MN) were studied after oral administration at two different times in the day (08.00 h and 20.00 h). Effects on blood pressure and heart rate after 3 min standing upright were measured in relation to the individual circadian control values.The pharmacokinetic parameters (C_max, t_max, AUC, t_1/2) did not differ after morning and after evening dosing, t_max being 5.2 h and 4.9 h, respectively. In contrast, the cardiovascular effects of IS-5-MN were clearly circadian phase-dependent. The maximum decrease in blood pressure decrease and increase in heart rate occurred significantly earlier after the evening (BPsys 2.8 h; BPdia 2.9 h; HR 3.8 h) than after the morning dose (BPsys 5.0 h; BPdia 6.0 h; HR 5.2 h). Thus, the peak haemodynamic effects coincided with the peak drug concentration after the morning dose, whereas the peak effect was in advance of the peak drug concentration after the evening dose of IS-5-MN.The data provide evidence of circadian phase-dependency in the dose-response relationship of oral IS-5-MN.     

Pharmacokinetics and metabolism of isosorbide-dinitrate after intravenous and oral administration

Summary The bioavailabilities of a conventional and two slow release 20 mg isosorbide dinitrate (ISDN) formulations were compared after oral administration in a three way cross-over study in 8 male volunteers. In a further group of 6 male volunteers the pharmacokinetics and metabolism of ISDN were investigated after intravenous infusion of a median dose of 14.1 mg for 2.5 h. A new analytical procedure was developed for the determination of isosorbide-5-mononitrate-2-glucuronide (IS-5-MN-2-Glu) and of isosorbide (IS). Kinetic data analysis on a molar basis was performed by the program package KINPAK providing model independent parameters. The median elimination half-lives of ISDN, IS-5-MN, IS-2-MN and IS-5-MN-2-Glu were 0.7, 5.1, 3.2 and 2.5 h, respectively. The systemic clearance of ISDN was 3.7 l/min and the distribution volume 2521 (3.1 l/kg). Apart from IS-5-MN-2-Glu, with a renal clearance of 5.9 l/min which suggested substantial glucuronidation in the kidney, the renal clearances of ISDN, IS-5-MN, IS-2-MN and the corresponding amounts excreted were negligible. 27.8% of the administered ISDN was excreted as IS-5-MN-2-Glu (8.7%) and IS (19.1%). Calculations based on the two mononitrate metabolites formed from ISDN showed an incomplete recovery of 84.1%, leading to the assumption that a simultaneous denitration to IS must have occurred. The rate of denitration at each nitro group in ISDN was almost twice as high as for the same position in the corresponding mononitrate. The bioavailability of the conventional ISDN formulation was 19%, although complete absorption was indicated by comparison of the percentages of mononitrate metabolites formed after the different routes of administration. On the same basis the absorption of the two sustained release formulations was found to be poor.Preliminary results were presented at the 2nd World Conference on Clinical Pharmacology and Therapeutics, Washington, 1983     

Concentrations of isosorbide dinitrate,isosorbide-2-mononitrate and isosorbide-5-mononitrate in human vascular and muscle tissue under steady-state conditions

Summary The concentrations of isosorbide dinitrate (ISDN), isosorbide-5-mononitrate (IS-5-MN) and isosorbide-2-mononitrate (IS-2-MN) were determined in plasma (PL), saphenous vein wall (SV) and pectoral muscle (PM) from 8 patients undergoing coronary bypass surgery.The patients were pretreated for 2 days with ISDN 240 mg per day (standard release formulation) in 4 doses of 40 mg and one dose of 80 mg. The plasma and tissue samples were obtained during the operation, 10–12 h after the last dose.Isosorbide-2-mononitrate and isosorbide-5-mononitrate were present in plasma and tissues in the same concentration ranges with molar concentration ratios of 0.88 (IS-2-MN: PM/PL), 0.85 (IS-5-MN: PM/PL), 0.99 (IS-2-MN: SV/PL) and 1.06 (IS-5-MN: SV/PL). Mean ISDN concentrations in tissue were considerably higher than in plasma; the molar concentration ratios were 4.9 (SM/PL) and 7.21 (SV/PL).The accumulation of ISDN in vessel walls may contribute to its greater vascular action compared to the mononitrates, but it may also facilitate the development of tolerance during long-term treatment.     

Pharmacokinetics of low-dose isosorbide dinitrate and metabolites after buccal or oral administration]

The kinetics of isosorbide dinitrate (ISDN; CAS 87-33-2) and its metabolites isosorbide-5-mononitrate (IS-5-MN) and isosorbide-2-mononitrate (IS-2-MN) were examined after buccal and oral administration of 5 mg ISDN. Twelve healthy volunteers were included in a randomized cross-over study. The mean dose-corrected AUCs for total nitrate in serum after the two different preparations were in the same range. The relative bioavailability of ISDN applied buccally, however, was more than twice that after oral application. The metabolism of ISDN differed depending on the route of administration, where the AUC-ratios ISDN: IS-2-MN: IS-5-MN were 1:2.7:19.4 after buccal and 1:5.7:53.4 after oral application respectively. The absorption rate constants Ka for ISDN and the MRT after buccal and oral application did not differ significantly. The same holds for the mean residence time.     

Single dose and steady-state pharmacokinetics of 4 mg and 8 mg oral salbutamol controlled-release in patients with bronchial asthma

Summary Fifteen patients with asthma were given salbutamol controlled-release (SCR) 4 mg or 8 mg twice daily for seven days, in a randomised double-blind cross-over design. Plasma salbutamol levels were measured after the first and fifteenth doses for a 12 h period following drug ingestion.At steady-state the geometric mean values for C_max were 8.2 ng/ml for 4 mg, and 16.1 ng/ml for 8 mg. Median t_max values were 300 and 240 min respectively. The geometric mean AUC (0–12) were 4507 ng·min·ml^–1 and 8980 ng·min/ml. Peak to trough fluctuation ratios were 0.577 and 0.572.There were no significant differences between 4 mg or 8 mg formulations, for any of the parameters measured, after appropriate corrections for dose. The concentration-time profiles at steady-state showed little fluctuation in plasma salbutamol levels over the twelve hour dosing interval. These results show that 4 mg and 8 mg formulations of SCR provide smooth plasma profiles at steady-state with a twice daily dosing regime.Part of this paper has been presented in abstract form to the British Thoracic Society, Newcastle, July 1988     

The pharmacokinetics of amiloride-hydrochlorothiazide combination in the young and elderly

Summary The pharmacokinetics of amiloride and hydrochlorothiazide were studied in 12 healthy young volunteers following a single dose of a fixed combination of amiloride and hydrochlorothiazide and in 11 elderly hypertensive patients at steady-state. Following modelling of the single dose data, simulated steady-state plasma concentrations for the 2 drugs were generated to examine the effect of age and/or hypertension on pharmacokinetics.The apparent systemic plasma clearance for both amiloride and hydrochlorothiazide was significantly reduced in the elderly when compared to the young (from 753 to 325 ml·min^–1, amiloride; and from 418 to 157 ml·min^–1, hydrochlorothiazide). The plasma concentrations at steady state for both drugs were greatly increased in the elderly patients (Amiloride: from 7 to 25 ng·ml^–1, C_ss,max; from 2 to 8 ng·ml^–1, C_ss,min; and from 4 to 14 ng·ml^–1, C_av; Hydrochlorothiazide: from 184 to 651 ng·ml^–1, C_ss,max; from 31 to 121 ng·ml^–1, C_ss,min; and from 89 to 273 ng·ml^–1, C_av).The decreased clearance of the diuretics in the elderly was believed due to deterioration of renal function, and there was a significant correlation between the plasma clearance of hydrochlorothiazide and creatinine clearance in both age groups (r=0.62, young;r=0.72, elderly).As a result of the pharmacokinetic findings caution may be indicated in the clinical dosage of the diuretics particularly when in fixed dose combination.     

Pharmacokinetics and dialysability of isradipine in chronic haemodialysis patients

Summary The pharmacokinetics of isradipine, a calcium-channel blocker, have been studied in eight patients on chronic haemodialysis. A single oral dose of 5 mg was administered on both a non-haemodialysis and a haemodialysis day and the plasma concentrations of isradipine were analyzed.The mean c_max, t_max, AUC, and t_1/2 in plasma on the non-haemodialysis day were 5.2 ng·ml^–1, 1.4 h, 23.8 ng·h·ml^–1, and 3.1 h, respectively. The dialysis clearance of isradipine was negligible (5.0 ml·min^–1).The t_1/2 values during haemodialysis were not significantly different from those observed during the same period post dose on the non-haemodialysis day. The study demonstrates that supplemental doses of isradipine are not necessary in these patients since isradipine is not significantly removed by haemodialysis.     

Differences in the production of methemoglobin during high-dose treatment with isosorbide dinitrate or isosorbide 5-mononitrate

12 patients with coronary heart disease were studied to see whether high doses of isosorbide dinitrate (ISDN, Corovliss) or isosorbide 5-mononitrate (IS-5-MN, Ismo) increase the erythrocyte methemoglobin production in an acute experiment and after 4 days of medication. The patients were divided into two groups. Group 1 (6 patients) was given a single dose of 80 mg ISDN on the morning of day 1 and Group 2 (6 patients) was given 80 mg IS-5-MN as a single oral dose. Under the influence of the IS-5-MN no change was observed from the initial methemoglobin (met-Hb) value (0.81% of the total Hb) at measurements performed 1 and 2 h after the administration of the drug. In Group 1 (ISDN) the initial met-Hb value was 0.58% of the total Hb, a slight increase to 0.70% being observed after 1 h and to 0.77% after 2 h (p less than 0.05). The patients were then treated as follows for a further 4 days: Group 1 480 mg ISDN/d, Group 2 480 mg IS-5-MN/d. On day 5 the initial met-Hb values in both groups were unchanged compared to day 1. The patients were then given first 80 mg ISDN (Group 1) or 80 mg IS-5-MN (Group 2) and 4 h later a single dose of 160 mg of the appropriate substance. In Group 2 (IS-5-MN) the met-Hb content remained unaffected. In Group 1 a slight increase of the met-Hb to 0.79% occurred 1 h after 80 mg ISDN and to 0.9% after 2 h (p less than 0.05). The dose of 160 mg ISDN gave rise to a further slight increase to 1.00% (after 1 h) and 1.13% (after 2 h) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

The tolerability,pharmacokinetics and lack of effect on plasma cholesterol of 447C88, an AcylCoA:Cholesterol Acyl Transferase (ACAT) inhibitor with low bioavailability,in healthy volunteers

447C88 (N-Heptyl-N-(2,4 difluoro-4-6-(2(-4-(2,2 dimethylpropyl)phenyl)ethyl)phenyl)urea) is an inhibitor of human microsomal AcylCoA:Cholesterol acyltransferase (ACAT) with an IC₅₀ of 10.2 ng·ml^–1 (23 nM). It is poorly absorbed but 5 mg·kg^–1·day^–1 completely abolishes the rise in plasma cholesterol in cholesterol-fed rats.In this study, twelve healthy, male volunteers received single, oral doses of 25, 50, 100, 200, 400 and 800 mg of 447C88 (n+8) or placebo (n+4) with food in a double-blind study with at least a week between occasions. The 400 mg dose was repeated after an overnight fast. Subsequently, fourteen different volunteers received a single 200 mg dose of 447C88 (n+8) or placebo (n+6) with food and, a week later, the same dose twice daily for 10 days; all doses were given with food.All doses were well tolerated with no significant changes in vital signs, full blood counts or plasma biochemical profiles. Plasma concentrations of 447C88 were unquantifiable after the fasting dose and low after all other doses. Mean C_max and AUC were 1.8 ng·ml^–1 and 9.0 ng·ml^–1·h after 200 mg rising to 5.4 ng·ml^–1 and 23.8 ng·ml^–1·h respectively after 800 mg; t_1/2 was 1.3 to 5.2 h. After 10 days dosing, plasma 447C88 concentrations were higher in the evening than the morning probably due to administration of the evening dose with more food. There were no significant changes in plasma triglcerides or total, LDL- or HDL-cholesterol after dosing with 447C88.     

The pharmacokinetics of ketanserin after a single dose and at steady-state in hypertensive subjects

Summary We have studied the pharmacokinetics of ketanserin in 6 hypertensive patients after a single oral 40 mg dose and at steady-state after 4 weeks treatment with 20 mg and then 40 mg 12-hourly.Pharmacokinetic variables after a single dose were similar to those reported in healthy volunteers, with median values for C_max 112 ng·ml^–1, t_max 1 h, and t_1/2 19 h. The corresponding values for the metabolite ketanserinol were C_max 155 ng·ml^–1, t_max 2 h, and t_1/2 25 h. The median AUC was 3.3 times greater for ketanserinol than for the parent drug.These results were used to predict the mean steady-state plasma concentrations of ketanserin and ketanserinol. Predicted values were on average similar to those observed after four weeks treatment with 40 mg 12-hourly, although there were marked differences between the observed and predicted values in some patients.There was no evidence of time- or dose-dependent kinetics for ketanserin, but the study had insufficient power to exclude the occurrence of these phenomena entirely.     

Modulation of allergen-induced nasal symptoms and mediator release by treatment with N-acetyl-aspartyl-glutamate (ZY15106)

The aim of this study was to evaluate the effects of the new anti-allergic drug, N-acetyl-aspartyl-glutamate (ZY15106), on allergen-induced nasal symptoms and mediator release. Fifteen outpatients suffering from seasonal allergic rhinitis due to grass pollen were included in the study. A nasal antigen challenge followed by evaluation of symptoms was performed in basal conditions. Ten of the 15 patients underwent sequential nasal lavages in order to evaluate allergen-induced mediator release. The study was performed in winter, when the patients were symptom free, and was a randomized single-blind crossover trial of a 6 % solution of ZY15106 (daily dosage: 48 mg) versus placebo (lactose). The drug and the placebo were administered intranasally q.i.d. for 1 week, with a 2-week interval between the two treatments. Treatment with ZY15106, but not with placebo, caused a significant reduction in nasal obstruction in the first 30 min after challenge and at 60 min and itching in the first 10 min after challenge, but did not reduce sneezing and rhinorrhoea. Moreover, ZY15106 significantly reduced the histamine release in 5 min postchallenge lavage (4.5 ng·ml^–1 after placebo administration vs 2.5 ng·ml^–1, after treatment with ZY15106). A reduction in immunoreactive LTC₄ release in the 5 and 10 min post-challenge lavages was observed after ZY15106 administration (placebo vs active treatment: at 5 min 2.9 ng·ml^–1 vs 1.4 ng·ml^–1; at 10 min: 2.25 ng·ml^–1 vs 0.9 ng·ml^–1). These results indicate that 1-week treatment with ZY15106 can reduce antigen-induced nasal obstruction and itching, and mediator release in human nasal airways. The clinical activity of ZY15106 in the treatment of allergic rhinitis may be related to its ability to inhibit mediator release.     

Effects of isosorbide dinitrate spray on central hemodynamics. Comparison with sublingual glyceryl trinitrate and isosorbide dinitrate

Effects of isosorbide dinitrate (ISDN) spray (Iso Mack Spray) on central hemodynamics were determined in comparison to sublingual glyceryl trinitrate (nitroglycerin) and ISDN, paying particular attention to their onset and duration of action. In nine patients with uncomplicated acute myocardial infarction, ISDN spray (2 sprays, 2.5 mg) glyceryl trinitrate (TNG, 0.3 mg) and ordinary ISDN tablet (5 mg) were administered by the single-blind crossover method under hemodynamic monitoring with a Swan-Ganz catheter. Systolic pulmonary artery pressure (s-PA), systolic pressure (s-BP) and heart rate were measured every minute for 10 min, every 5 min for the subsequent 20 min and thereafter every 15 to 30 min up to 120 min. Using s-PA as a measure of nitrate action, the onset and duration of action as well as the magnitude of change was compared among the three drugs. ISDN spray had a quick onset of action (2.67 +/- 2.4 min, mean +/- SD) comparable to that of TNG (2.67 +/- 1.00 min), while ISDN spray had a long duration of action (57.4 +/- 42.1 min), which was comparable to that of sublingual ISDN (85.6 +/- 39.5 min, ns) and was significantly longer than that of TNG (11.4 +/- 6.4 min, p less than 0.05). ISDN spray (2.5 mg) showed the same hemodynamic changes as were induced by 0.3 mg TNG or 5 mg ISDN. The results of this study led us to conclude that ISDN spray is a useful agent which induces the abortion of anginal attacks by its quick onset and long duration of action.