The pharmacokinetics and safety of porfimer after repeated administration 30-45 days apart to patients undergoing photodynamic therapy.

BACKGROUND: Porfimer is an intravenous (i.v.) injectable photosensitizing agent used in the photodynamic treatment of tumours and of high-grade dysplasia in Barrett's oesophagus. AIM: To assess the pharmacokinetics as well as the safety profiles of porfimer after a first and a second dose administered 30-45 days apart in patients undergoing photodynamic therapy. METHODS: Nineteen patients (16 with cholangiocarcinoma) were enrolled. Porfimer sodium was administered by i.v. injection over 3-5 min. Blood samples were collected prior to starting i.v. drug injection and postdose at different time points after the first and second administrations. RESULTS: Porfimer exposure values after the second administration were statistically higher than those observed after the first administration, suggesting a slight accumulation of porfimer following repeated administration. The apparent mean elimination half-life of porfimer increased from 410 h after the first administration to 725 h after the second administration. The safety profiles of porfimer after a first and a second administration were similar and did not raise additional concern. Eight patients experienced nine serious adverse events. Only photosensitivity was deemed study-drug related. CONCLUSION: Porfimer appears to display a safe and tolerable profile when used in patients requiring a second photodynamic therapy within 45 days.

Efficacy and safety of single-triple capsules of bismuth biskalcitrate, metronidazole and tetracycline, given with omeprazole, for the eradication of Helicobacter pylori: an international multicentre study.

BACKGROUND: The high prevalence of Helicobacter pylori resistance to metronidazole demands treatments more effective than standard bismuth-based triple therapy against these strains. AIM: To evaluate the H. pylori eradication rate in both metronidazole-sensitive and -resistant strains following quadruple therapy using single-triple capsules of bismuth biskalcitrate, metronidazole and tetracycline, given with omeprazole. METHODS: One hundred and seventy valid patients with duodenal ulcer, gastric ulcer or non-ulcer dyspepsia were treated in eight centres located in five countries. H. pylori was confirmed at baseline using 13C-urea breath test, histology and/or culture. Patients received three single-triple capsules q.i.d. and omeprazole, 20 mg b.d., for 10 days. Each capsule contained bismuth biskalcitrate, 140 mg (as 40 mg Bi2O3 equivalent), metronidazole, 125 mg, and tetracycline, 125 mg. 13C-Urea breath test was repeated at least 4 and 8 weeks post-treatment. RESULTS: Overall eradication rates were 93% (158/170) by modified intention-to-treat analysis and 97% (142/146) by per protocol analysis. Eradication rates were 93% (40/43) and 95% (38/40) for strains resistant to metronidazole and 95% (82/86) and 99% (75/76) for strains sensitive to metronidazole by modified intention-to-treat and per protocol analysis, respectively. CONCLUSION: This omeprazole-bismuth biskalcitrate-metronidazole-tetracycline 10-day regimen is a very effective and well-tolerated treatment, which overcomes metronidazole resistance.

Rectal tissue, plasma and urine concentrations of mesalazine after single and multiple administrations of 500 mg suppositories to healthy volunteers and ulcerative proctitis patients.

OBJECTIVE: Patients with ulcerative proctitis may have rectal mucosal properties different from healthy volunteers. This project compared the pharmacokinetics of rectally administered mesalazine in these two populations. METHODS: In two separate studies, nine patients with ulcerative proctitis and 16 healthy volunteers received a single 500 mg mesalazine suppository and then 500 mg every 8 h for 5 days. Blood samples were collected for 12 h in healthy volunteers and 30 h in patients, and urine for 24 h in healthy volunteers and 30 h in patients. Rectal biopsies were performed 8 h after the last dose. RESULTS: After a single dose to patients, mean mesalazine half-life (s.d.) was 5.0 (3.6) h. At steady-state, means (s.d.) were 89.1 (78.9) ng/mL for C(min), 361.1 (240.8) ng/mL for C(max), and 7.1 (7.3) h for half-life. Mean (range) rectal mesalazine concentrations were 167 (1.4-541.6) ng/mg tissue. After a single dose in healthy volunteers, mean (s.d.) half-life was 4.0 (4.7) h. At steady-state, means (s.d.) were 22.4 (61.6) ng/mL for C(min), 359.4 (166.3) ng/mL for C(max), and 0.9 (0.5) h for half-life. CONCLUSION: Mesalazine is released in the rectum of patients, with a bioavailability of about 40%. Tissue distribution is also appreciable. Both parameters appear higher than in healthy volunteers.

Intrarectal administration of 5-aminosalicylic acid to rabbits and dogs.

Intrarectal administration of 5-aminosalicylic acid (5-ASA) to rabbits and dogs was performed to obtain safety data. Groups of rabbits and dogs received twice daily intrarectal doses of 250, 500 or 1000 mg 5-ASA for 14 consecutive days. Treatment had no adverse effect on the behaviour or performance of the animals and microscopic examination revealed no evidence of systemic or local toxicity.

Bismuth-based quadruple therapy with bismuth subcitrate, metronidazole, tetracycline and omeprazole in the eradication of Helicobacter pylori.

BACKGROUND: A previous study showed that 14 days of qid bismuth-based triple therapy with tetracycline 500 mg, metronidazole 250 mg and colloidal bismuth subcitrate 120 mg resulted in excellent Helicobacter pylori eradication rates (89.5%). The present study looked at a shorter treatment period by adding omeprazole and by reducing the dose of tetracycline. METHODS: One hundred sixty-one patients with H pylori confirmed by histology and (13)carbon urea breath test were included in the study. They were treated for seven days with bismuth subcitrate 120 mg plus metronidazole 250 mg plus tetracycline 250 mg qid plus omeprazole 20 mg bid (OBMT). Patients were 18 to 75 years of age and had dyspepsia with or without a history of peptic ulcer. Patients with irritable bowel syndrome, active ulcer or previous attempt at eradication, or those who had used antibiotics or antiulcer drugs in the previous 30 days were excluded. Eradication was determined by two (13)carbon urea breath tests done one and three months, respectively, after treatment. Strains with minimal inhibitory concentrations of 8 microg/mL or higher were considered to be resistant to metronidazole. RESULTS: The overall per protocol eradication rate was 84%-89.5% in metronidazole-sensitive and 70.8% in metronidazole-resistant strains. Modified intent-to-treat analysis resulted in a 80% eradication rate--82.5% in metronidazole-sensitive and 66.7% in metronidazole-resistant strains. Only one patient discontinued treatment because of adverse events. CONCLUSIONS: The OBMT regimen used in this study is safe and effective against metronidazole-sensitive H pylori strains.

Bismuth-based triple therapy with bismuth subcitrate, metronidazole and tetracycline in the eradication of Helicobacter pylori: a randomized, placebo controlled, double-blind study.

OBJECTIVE: To determine the rate of Helicobacter pylori eradication following bismuth-based triple therapy with colloidal bismuth subcitrate, tetracycline hydrochloride and metronidazole. PATIENTS AND METHODS: One hundred and eleven patients were randomly assigned, in a two to one ratio, to colloidal bismuth subcitrate 120 mg qid plus metronidazole 250 mg qid plus tetracycline 500 mg qid (Gastrostat), or matching placebo tablets and capsules for 14 days. Presence or absence of H pylori was documented by histology at entry and at least 28 days after treatment. Patients had dyspeptic symptoms with or without a history of peptic ulcer. Patients with any previous attempt(s) at eradication of H pylori, who used bismuth, antibiotics, H2 receptor antagonists or proton pump inhibitors in the previous four weeks were excluded. RESULTS: Fifty-three of 59 (90%) patients on bismuth-based treatment and only one of 35 (3%) on placebo achieved eradication by per protocol analysis. Fifty-three of 65 (82%) patients on bismuth-based treatment achieved eradication, while only two of 34 (5%) achieved eradication on placebo by intention to treat analysis. Eradication rates for bismuth-based treatment across sites ranged from 83% to 100%. Only two patients in the bismuth-based treatment group (4%) and one in the placebo group (3%) discontinued treatment because of adverse events. CONCLUSIONS: Colloidal bismuth subcitrate plus metronidazole plus tetracycline, given in the doses studied for 14 days, is safe and highly effective against H pylori infection and would be appropriate as a first-line therapy for eradication.

Influence of sex, age and smoking status on patient comfort during gastroscopy with pharyngeal anesthesia by a new benzocaine-tetracaine preparation.

Thirty-seven patients underwent gastroscopy under pharyngeal anaesthesia with benzocaine-tetracaine (Endospray; Axcan Pharma). Patients recorded their perception of intubation, of the rest of the procedure, of taste and of throat well-being on visual analogue scales. Throat well-being and taste scores were better for men than for women. There was a strong trend for smokers to be more intolerant to intubation than nonsmokers. There was a weak but significant correlation for younger patients to be more intolerant to intubation. This study points to age and smoking status as possible factors influencing the perception of gastroscopy under pharyngeal anesthesia.

A comparison of triamcinolone acetonide nasal aerosol spray and fluticasone propionate aqueous solution spray in the treatment of spring allergic rhinitis.

BACKGROUND: Many nasal corticosteroids with different potencies and formulations are available, but they have all been proven safe and effective. The clinical relevance, if any, of these differences is not yet completely established. OBJECTIVE: We sought to compare the efficacy, safety, and patients' acceptance of triamcinolone acetonide aerosol spray and fluticasone propionate aqueous solution in the treatment of spring allergic rhinitis. METHODS: After a drug-free baseline evaluation, patients with rhinitis were randomized to receive either a triamcinolone aerosol spray of 110 microg in each nostril once daily (n = 117) or a fluticasone solution spray of 100 microg in each nostril once daily (n = 116) in a single-blind, parallel-group study. The Rhinitis Index Score (sum of scores of symptoms on a scale from 0 to 3) was evaluated daily, in the morning before drug administration, for 21 days. The efficacy of each treatment was assessed by the mean reduction from baseline in the Rhinitis Index Score and in individual symptom scores. Patients' acceptance of the study drugs was also monitored by a daily questionnaire. RESULTS: Reductions of the Rhinitis Index Score (mean +/- SEM) were 4.20 +/- 0.21 and 4.60 +/- 0.21 for triamcinolone and fluticasone, respectively (p = 0.23). There were no statistically significant differences between the drugs in the reduction of any of the individual symptoms. Patients expressed statistically significant differences between the drugs regarding acceptance; different properties of the aerosol and the solution were appreciated differently. CONCLUSIONS: This study shows that triamcinolone acetonide aerosol and fluticasone propionate solution sprays are both clinically equally effective, safe, and well tolerated for the treatment of spring pollen allergic rhinitis.

Pharmacokinetics and safety of single intravenous and oral doses of dolasetron mesylate in healthy women.

Twenty-four healthy women received 2.4 mg kg-1 dolasetron mesylate (1.8 mg kg-1 dolasetron base) by a 10 min intravenous administration and by oral administration. Pharmacokinetics of dolasetron and of its active reduced metabolite MDL 74156 were monitored for 48 h in plasma. Urine was collected from 0 to 48 h, blood pressure and heart rate were measured at 0, 0.08, 1, 2, 12, 24, and 36 h, and ECGs were measured at 0, 0.08 (intravenous only), 1, 2, and 36 h after dosing. Dolasetron was widely distributed and rapidly reduced (mean t1/2 = 0.23 h) to MDL 74156 (mean t1/2 = 8.05 and 9.12 h after intravenous and oral administration respectively). MDL 74156 was extensively distributed; between 27 (oral route) and 33% (intravenous route) was eliminated unchanged in urine. Safety assessment showed mild to moderate headache, dizziness, and hot flushes after the intravenous administration and headache, abdominal cramps or pain, and constipation after oral administration. Small and clinically non-significant changes in PR, QRS, and QTc intervals were observed. We conclude that there is no obvious difference in dolasetron pharmacokinetics between healthy women and men and that dolasetron can be used as safely in women as in men.

Pharmacokinetics of single intravenous and oral doses of dolasetron mesylate in healthy elderly volunteers.

Dolasetron mesylate (MDL 73,147EF, Anzemet; Hoechst Marion Roussel, Laval, Canada) is a 5-HT3 receptor antagonist undergoing clinical evaluation for use as an antiemetic agent. The pharmacokinetics of dolasetron and its reduced metabolite (MDL 74,156) were studied after administration of single intravenous and oral doses of dolasetron mesylate 2.4 mg/kg in 18 healthy elderly subjects. Expressed as the dolasetron base, this dose was 1.8 mg/kg. Dolasetron was rapidly metabolized to the reduced metabolite, which appeared in plasma within 10 minutes after intravenous or oral administration. The mean half-life (t1/2) of dolasetron was 0.24 hours after intravenous administration and 0.50 hours after oral administration. The pharmacokinetic parameters of the reduced metabolite were similar after intravenous and oral administration. The apparent absolute bioavailability of the reduced metabolite was 89%, and it had an elimination t1/2 of approximately 7 hours and an apparent volume of distribution (Vd beta) of 4.69 L/kg. Dolasetron was not detected in urine. Metabolites were excreted in urine almost completely within 24 hours of administration. The primary metabolite detected in urine was the (+)-enantiomer of the reduced metabolite, which accounted for 25.35% (+/- 7.79%) and 18.88% (+/- 7.65%) of the intravenous and oral doses, respectively. Hydroxylated metabolites accounted for 5% or less of the total dose via either route. The pharmacokinetics of the reduced metabolite after single intravenous or oral doses in elderly volunteers were consistent with pharmacokinetics observed in both young healthy men and cancer patients receiving high-dose cisplatin chemotherapy. Dosage adjustments of dolasetron mesylate on the basis of age do not appear to be necessary.

The influence of time of administration on the pharmacokinetics of a once-a-day diltiazem formulation: morning against bedtime.

Twenty-three young, healthy, male volunteers received, in a randomized crossover design, 240 mg of a once-a-day diltiazem formulation at 08:00 (AM) or 22:00 (HS) for 6 days. A 7 day washout period was observed between the two modes of administration. Diltiazem plasma concentrations were monitored every hour for 24 h and at 30, 36, and 48 h after the last dose. Differences were found between AM and HS dosing for Cmin (mean (SD) = 47 center dot 2 (25 center dot 8) against 39 center dot 6 (21 center dot 1) ng mL-1, p = 0 center dot 038), AUC0-24 (2008 (814) against 1754 (714) ng h mL-1, p = 0 center dot 024), and AUC0-48 (2662 (1244) against 2395 (238) ng h mL-1, p = 0 center dot 034). Overall the two modes of administration did not produce bioequivalent pharmacokinetic profiles. Also HS dosing gave significantly higher plasma concentrations of diltiazem in the early morning hours when the incidence of cardiovascular events is higher. If one assumes a strong correlation between plasma concentrations and myocardial protection then HS dosing should be recommended for QD formulation of diltiazem. Clinical studies should be performed to confirm this theoretical pharmacokinetic advantage.

Release of 5-ASA from Pentasa in patients with Crohn's disease of the small intestine.

BACKGROUND: Pentasa is a controlled-release tablet made from semipermeable microspheres and designed to continuously deliver therapeutic quantities of 5-ASA (5-aminosalicylic acid) throughout the gastrointestinal tract. Scintigraphic studies in healthy subjects have documented that 5-ASA release could occur in the small intestine. We tested here the disintegration of Pentasa in the digestive tract of nine patients with Crohn's disease of the small intestine. MATERIALS: Each patient was given, after breakfast, a 250 mg tablet of Pentasa containing samarium-153 oxide. For 8 h the progression of the isotope in the gastrointestinal tract was followed using gamma camera scintigraphy. Plasma measurement of 5-ASA and acetylated 5-ASA was used to verify the liberation and absorption of 5-ASA. RESULTS: The Pentasa tablet appeared completely dissolved in the stomach by 117 +/- 18 min. Samarium oxide was first detected in the small intestine 60 +/- 5 min after its ingestion; it reached the colon after 280 +/- 13 min and it was completely absent from the small intestine at 360 +/- 26 min. Plasma concentrations of 5-ASA started to rise after 67 +/- 7 min and were maximal at 222 +/- 25 min. CONCLUSION: In patients with Crohn's disease of the small intestine, Pentasa microgranules start releasing 5-ASA in the proximal small intestine, acting locally to exert its beneficial effect.

Pharmacokinetics and pharmacodynamics of a slow-release formulation of diltiazem after the administration of a single and repeated doses to healthy volunteers.

Diltiazem is a calcium antagonist used in angina pectoris and hypertension. There is little information concerning the slow-release (SR) formulation in the literature. The pharmacokinetics of diltiazem SR (120 mg) have been assessed over a 36h period in healthy volunteers after single- (SD) and multiple-dose (MD) administrations. Cmax, AUC0-36, and AUC0-infinity were significantly increased at steady state compared to the extrapolated SD values, suggesting accumulation of the drug. Renal and cardiovascular parameters have also been assessed at intervals of 3-6h during baseline (B) and following single and multiple doses of diltiazem SR. Diuresis over a 24 h period was increased, but not significantly, by the administration of diltiazem SR i.e. 1782 ml (MD) and 1915 ml (SD), versus 1626 ml (B). Natriuresis and creatinine clearance were slightly decreased by diltiazem SR, compared to B values; this might be due to the relatively short period over which steady state was maintained (five days) and the effects of norepinephrine and angiotensine II on renal vasculature and the pharmacokinetics of diltiazem SR. No increase in the systolic blood pressure occurred after the administration of diltiazem SR; diastolic blood pressure and PR interval were decreased and increased respectively by diltiazem SR. These results do not appear to be clinically significant. Finally, no relation was found between the pharmacokinetics and pharmacodynamics of diltiazem. This may be attributed to the absence of clinically significant effects in healthy volunteers, the presence of active metabolites, the pharmacokinetics of the SR formulation and/or the accumulation of the drug at steady state.

Bioavailability of metformin in tablet form using a new high pressure liquid chromatography assay method.

Twenty-four young healthy volunteers received a single dose of metformin 500 mg (Glucophage, Nordic Laboratories, Canada) in tablet form. Plasma concentrations were determined by HPLC in samples collected prior to and 0.33, 0.66, 1, 1.33, 1.66, 2, 2.5, 3, 4, 5, 6, 7, 8, 10, 12, 15, 18, 24, and 30 h after dosing. Mean (+/- SD) Cmax was 682.1 (160.6) ng ml-1 at a mean (+/- SD) tmax of 2.4 (0.93) h. Overall elimination was monoexponential with a mean (+/- SD) half-life of 3.16 (0.47) h. We conclude that metformin is rapidly absorbed from this formulation and is also rapidly eliminated. Extrapolation to steady state predicts that equilibrium will be reached within 24 h.

Diltiazem pharmacokinetics in elderly volunteers after single and multiple doses.

In young healthy volunteers diltiazem does not have linear kinetics between single and multiple doses. Elimination half-life increases and gives AUC's and Cmax higher than those predicted from single dose data. Kinetics of diltiazem were assessed in 16 healthy elderly after a single 60 mg dose and in 24 healthy elderly after 60 mg every 8 h for 7 days. Thirteen participants completed both studies. Elimination half-life, AUC0-24, AUC0-infinity, and Cmax were (mean +/- SE) 7.4 (1.2) h, 349 (34) ng/ml.h, 392 (44) ng/ml.h, and 43 (5) ng/ml respectively after a single dose. After multiple doses elimination half-life, AUC0-48, AUC0-infinity, Cmax and Cmin were respectively 5.7 (0.3) h, 974 (107) ng/ml.h, 1022 (108) ng/ml.h, 102 (7) ng/ml and 43 (5) ng/ml. Exploratory statistics on the 13 volunteers common to both studies showed that the ratio of AUC desacetyl-diltiazem (DAD)/AUC diltiazem rose between single and multiple doses while elimination half-life of both diltiazem and N-desmethyl-diltiazem (MA), tmax, and AUC MA/AUC diltiazem were not affected. The conclusion of this study is that elimination half-life of diltiazem does not increase in elderly between single and multiple doses, possibly due to an increased biotransformation into DAD.

Pharmacokinetics of intravenous diltiazem and five of its metabolites in patients with chronic renal failure and in healthy volunteers.

The pharmacokinetics of diltiazem were studied in seven patients with chronic renal failure (CRF) not requiring dialysis and in three healthy volunteers after a rapid i.v. infusion of 20 mg. Mean plasma concentrations at the end of infusion were 3.15 times higher in patients with CRF than in healthy volunteers. From 0.5 to 12 h post-infusion, the difference remained between 25 per cent and 73 per cent. Mean AUC0-infinity was statistically greater in patients than in volunteers while mean V area, CLtot, and CLren were statistically lower. The t1/2 alpha and t1/2 beta values were not significantly (p greater than 0.05) different between patients and volunteers. Renal excretion was statistically more important in volunteers (6.6 per cent of the dose) than in patients (1.2 per cent of the dose). We therefore conclude that CRF does not influence t1/2 beta of diltiazem but it interferes with the extent and possibly the rate of its extravascular distribution. That could result in transient high plasma concentrations after rapid i.v. infusion.

Pharmacokinetics of oral diltiazem and five of its metabolites in patients with chronic renal failure.

The pharmacokinetics of oral diltiazem were studied in 10 patients with chronic renal failure not requiring dialysis and in five healthy volunteers after a single dose of 120 mg. We found that patients with chronic renal failure had lower amounts of unchanged diltiazem and of its main metabolite (MA) in urine and a trend to have slightly higher values of plasma concentration. Since the terminal elimination phase is not affected by chronic renal failure we conclude that this trend is probably the result of alterations in the volume of distribution of diltiazem in these patients.

Chronic effects of diltiazem on the hemodynamic and sympathoadrenal tone in responsive and nonresponsive hypertensive patients at rest and during isometric exercise.

The objective of this study was to identify hemodynamic and sympathetic parameters that could be predictive of the hypotensive response to diltiazem (DTZ). Parameters of cardiovascular functions were measured from M-mode echocardiography and the index of sympathoadrenal tone was given by circulating catecholamine levels in 25 normotensive subjects and in 19 mild-to-moderate hypertensive patients before and after 2 months as well as 12 months (responders only) of treatment with DTZ (SR 120 or 180 mg b.i.d.). The responder (R) subgroup (63% of total population) consisted of patients who showed a decrease in mean arterial pressure (MAP) greater than or equal to 5 mm Hg (day average) by ambulatory blood pressure (BP) monitoring. Before treatment, R patients were characterized by higher circulating norepinephrine (NE) levels and by hyperkinetic cardiac functions [increased heart rate (HR), cardiac index (CI), and mean velocity of circumferential fiber shortening, p less than 0.05] while peripheral resistance was normal. In contrast, nonresponders (NR) were characterized by higher peripheral resistance (p less than 0.05) and normal cardiac functions. Following treatment, hyperkinetic cardiac functions were normalized but the peripheral resistance was unchanged in the R subgroup whereas in the NR subgroup, cardiac parameters were slightly increased and the peripheral resistance was normalized. During isometric exercise, cardiac performance was found to be impaired (p less than 0.05) and the increase in peripheral resistance was greater (p less than 0.05) in the R subgroup before treatment, whereas those responses were normal in the BR group.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of mild-to-moderate hypertension: comparison between a calcium-channel blocker and a potassium-sparing diuretic.

In a multicenter study, 61 patients, 18-70 years of age, with mild-to-moderate hypertension [diastolic blood pressure (DBP) 95/114] completed a 28-week treatment. After initial placebo washout, patients were randomly allocated either to diltiazem or hydrochlorothiazide/triamterene. At the end of 12 weeks, the patients continued on the same medication if their goal blood pressure achieved (DBP less than 90; or 10 mm Hg below baseline). If not, the alternate agent was added (either diltiazem + hydrochlorothiazide/triamterene or hydrochlorothiazide/triamterene + diltiazem). At the end of 28 weeks, the intent-to-treat analysis showed that 90% on diltiazem alone, 73.7% on hydrochlorothiazide/triamterene alone, 71.4% on (diltiazem + hydrochlorothiazide/triamterene), and 57.1% on (hydrochlorothiazide/triamterene + diltiazem) achieved goal BP. End point mean values of BP and heart rate after adjusting for sex, baseline values, age, and weight showed no significant difference between groups. Forty-six percent on hydrochlorothiazide/triamterene alone and 24% on diltiazem alone reported one or more adverse events, possibly related to study medication. Patients with diltiazem as the first choice had better BP control than those on hydrochlorothiazide/triamterene alone (81.5% vs. 69.7%). Furthermore, among non-goal achievers at week 12, there was a greater response in the group when hydrochlorothiazide/triamterene was added to diltiazem than when diltiazem was added to hydrochlorothiazide/triamterene. This study suggests that in mild-to-moderate hypertension, diltiazem is better than hydrochlorothiazide/triamterene as first line therapy.

Diltiazem pharmacokinetics in elderly volunteers after single and multiple doses.

In young healthy volunteers diltiazem does not have linear kinetics between single and multiple doses. Elimination half-life increases and gives AUC's and Cmax higher than those predicted from single dose data. Kinetics of diltiazem were assessed in 16 healthy elderly after a single 60 mg dose and in 24 healthy elderly after 60 mg every 8 h for 7 days. Thirteen participants completed both studies. Elimination half-life, AUC0-24, AUC0-infinity, and Cmax were (mean +/- SE) 7.4 (1.2) h, 349 (34) ng/ml.h, 392 (44) ng/ml.h, and 43 (5) ng/ml respectively after a single dose. After multiple doses elimination half-life, AUC0-48, AUC0-infinity, Cmax and Cmin were respectively 5.7 (0.3) h, 974 (107) ng/ml.h, 1022 (108) ng/ml.h, 102 (7) ng/ml and 43 (5) ng/ml. Exploratory statistics on the 13 volunteers common to both studies showed that the ratio of AUC desacetyl-diltiazem (DAD)/AUC diltiazem rose between single and multiple doses while elimination half-life of both diltiazem and N-desmethyl-diltiazem (MA), tmax, and AUC MA/AUC diltiazem were not affected. The conclusion of this study is that elimination half-life of diltiazem does not increase in elderly between single and multiple doses, possibly due to an increased biotransformation into DAD.