Pharmacokinetics of the R- and S-enantiomers of oxybutynin and N-desethyloxybutynin following oral and transdermal administration of the racemate in healthy volunteers.

PURPOSE: To characterize the enantiomers of oxybutynin (OXY) and N-desethyloxybutynin (DEO) following transdermal and oral administration. METHODS: OXY was administered either as a single transdermal system over a 96 h wear period or as a single 5 mg immediate-release tablet to 18 healthy male and female subjects in a randomized, open-label, two-way crossover design. Blood samples were collected for 108 h after application of the transdermal system and for 6 h after oral administration. Plasma concentrations of the R- and S-enantiomers of OXY and DEO were assayed by LC-MS/MS. Enantiomer in vitro skin flux was evaluated using human cadaver skin. RESULTS: In vitro skin flux studies demonstrated equal absorption of R and S- OXY. Plasma concentrations and pharmacokinetic parameters of the R-enantiomers of OXY and DEO were slightly lower than the S-enantiomers following transdermal OXY. The relative AUC values were S-OXY>S-DEO>R-OXY>R-DEO. The AUC ratios of DEO/ OXY were less than 1 for both the R- and S- enantiomers. Following oral dosing, plasma DEO concentrations greatly exceeded OXY resulting in relative AUC values of R-DEO>S-DEO>S-OXY>R-OXY. The mean AUC ratios of S- and R-DEO/OXY were 3.25 and 8.93, respectively. CONCLUSIONS: Stereoselective metabolism of OXY was evident following both transdermal and oral administration of OXY. The reduced pre-systemic metabolism of transdermally administered OXY compared to oral administration resulted in not only significantly lower DEO plasma concentrations, but also a different metabolite pattern. The differences between R-OXY and R-DEO following the two routes of administration support the potential for comparable clinical efficacy and reduced anticholinergic side-effects with transdermal treatment.

A short-term, multicenter, randomized double-blind dose titration study of the efficacy and anticholinergic side effects of transdermal compared to immediate release oral oxybutynin treatment of patients with urge urinary incontinence.

PURPOSE: We compared the short-term efficacy, safety and tolerability of transdermal versus oral oxybutynin in adults with urge urinary incontinence. MATERIALS AND METHODS: Volunteers with detrusor instability currently responding to oral immediate release oxybutynin were enrolled in our study. Those patients presenting with recurrence of incontinent symptoms after a 2-week washout underwent confirmatory cystometrogram with subsequent randomization to transdermal or oral treatment. Matching active and placebo medications included matrix patches applied twice weekly and capsules taken 2 or 3 times daily. Dose titration was based on anticholinergic symptoms. Outcome measures included comparison of baseline to 6 week changes in incontinence episodes on a 3 day urinary diary, a visual analog scale for efficacy and anticholinergic symptoms reported on a questionnaire. Safety monitoring included adverse events and skin tolerability of the transdermal system. RESULTS: A total of 76 patients were enrolled and 74 completed at least 4 weeks of treatment. Mean age in the transdermal and oral groups was 64 and 63 years, and 87% and 97% were female, respectively. Daily incontinent episodes decreased in the transdermal and oral groups (7.3 to 2.4 [66%] and 7.4 to 2.6 [72%], respectively, p = 0.39). The visual analog scale reduction in urinary leakage improved from washout in both groups (p <0.0001) with no difference between them (p = 0.9). Dry mouth occurred in significantly fewer patients in the transdermal (38%) compared with those in the oral group (94%, p <0.001). Of the patients in the transdermal group 67% noticed a reduction in dry mouth severity compared with previous oral treatment, and 90% had none or mild skin erythema. CONCLUSIONS: Transdermal delivery of oxybutynin resulted in comparable efficacy and a significantly improved anticholinergic side effect profile compared with oral administration in adults with urge urinary incontinence.

Interrelationships among lipoprotein levels, sex hormones, anthropometric parameters, and age in hypogonadal men treated for 1 year with a permeation-enhanced testosterone transdermal system.

Serum lipoproteins and cardiovascular risk are affected by endogenous and exogenous sex hormones. As part of a multicenter evaluation of a permeation-enhanced testosterone transdermal system (TTD), the interrelationships among serum lipoproteins, hormone levels, anthropometric parameters, and age were investigated in 29 hypogonadal men. Subjects (aged 21-65 yr) were first studied during prior treatment with im testosterone esters (IM-T), then during an 8-week period of androgen withdrawal resulting in a hypogonadal state (HG), and finally during a 1-yr treatment period with the TTD. Compared with treatment with IM-T, the HG period produced increases in high density lipoprotein [HDL; 12.0 +/- 1.6% (+/-SEM); P<0.001] and total cholesterol (4.2 +/- 1.9%; P: = 0.02) and a decrease in the cholesterol/HDL ratio (-9.7 +/- 2.8%; P = 0.02). Compared with the HG period, TTD treatment produced decreases in HDL (-7.6 +/- 2.5%; P = 0.002) and increases in the cholesterol/HDL ratio (9.0 +/- 2.5%; P = 0.01) and triglycerides (20.7 +/- 6.4%; P: = 0.03). Small decreases in total cholesterol (-1.2 +/- 1.8%; P: = 0.1) and low density lipoprotein (-0.8 +/- 2.6%; P = 0.07) were also observed during TTD, but did not reach statistical significance. Likewise, there were no significant differences between the IM-T and TTD treatments. Serum HDL levels showed a strong negative correlation with body mass index and other obesity parameters in all three study periods (r < -0.45; P < 0.02). During treatment with TTD, serum testosterone levels also correlated negatively with body mass index (r = -0.621; P < 0.001). As a consequence of these relationships, a positive trend was observed between HDL and testosterone levels during TTD treatment (r = 0.336; P = 0.07). Interestingly, the changes in lipoprotein levels during TTD treatment indicated a more favorable profile (decrease in cholesterol and low density lipoprotein levels) with increasing age of the patients. In hypogonadal men the effects of transdermal testosterone replacement on serum lipoproteins appear consistent with the physiological effects of testosterone in eugonadal men.

Pharmacokinetics, efficacy, and safety of a permeation-enhanced testosterone transdermal system in comparison with bi-weekly injections of testosterone enanthate for the treatment of hypogonadal men.

The pharmacokinetics, efficacy, and safety of the Androderm testosterone (T) transdermal system (TTD) and intramuscular T enanthate injections (i.m.) for the treatment of male hypogonadism were compared in a 24-week multicenter, randomized, parallel-group study. Sixty-six adult hypogonadal men (22-65 years of age) were withdrawn from prior i.m. treatment for 4-6 weeks and then randomly assigned to treatment with TTD (two 2.5-mg systems applied nightly) or i.m. (200 mg injected every 2 weeks); there were 33 patients per group. Twenty-six patients in the TTD group and 32 in the i.m. group completed the study. TTD treatment produced circadian variations in the levels of total T, bioavailable T, dihydrotestosterone, and estradiol within the normal physiological ranges. i.m. treatment produced supraphysiological levels of T, bioavailable T, and estradiol (but not dihydrotestosterone) for several days after each injection. Mean morning sex hormone levels were within the normal range in greater proportions of TTD patients (range, 77-100%) than i.m. patients (range, 19-84%). Both treatments normalized LH levels in approximately 50% of patients with primary hypogonadism; however, LH levels were suppressed to the subnormal range in 31% of i.m. patients vs. 0% of TTD patients. Both treatments maintained sexual function (assessed by questionnaire and Rigiscan) and mood (Beck Depression Inventory) at the prior treatment levels. Prostate-specific antigen levels, prostate volumes, and lipid and serum chemistry parameters were comparable in both treatment groups. Transient skin irritation from the patches was reported by 60% of the TTD patients, but caused only three patients (9%) to discontinue treatment. i.m. treatment produced local reactions in 33% of patients and was associated with significantly more abnormal hematocrit elevations (43.8% of patients) compared with TTD treatment (15.4% of patients). Gynecomastia resolved more frequently during TTD treatment (4 of 10 patients) than with i.m. treatment (1 of 9 patients). Although both treatments seem to be efficacious for replacing T in hypogonadal men, the more physiological sex hormone levels and profiles associated with TTD may offer possible advantages over i.m. in minimizing excessive stimulation of erythropoiesis, preventing/ameliorating gynecomastia, and not over-suppressing gonadotropins.

Androgen replacement in the treatment of Klinefelter's syndrome: efficacy and safety of a nonscrotal permeation-enhanced testosterone transdermal system.

OBJECTIVE: To report the efficacy and safety of a permeation-enhanced nonscrotal testosterone transdermal (TTD) system for the treatment of Klinefelter's syndrome. METHODS: Fifteen male patients with Klinefelter's syndrome, including 12 patients who received previous intramuscular (IM) treatment with testosterone esters, were part of the study population from three phase III clinical studies; 13 completed the studies. Patients applied two TTD systems nightly for 6 months or more. Nocturnal erections were assessed by RigiScan monitoring; sexual function was evaluated by using the Watts and Davidson questionnaires. Hypogonadal symptoms were determined by direct patient questioning. RESULTS: Mean morning serum testosterone levels increased to within normal range in all 13 patients (from 5.9 +/- 3.2 nmol/L at hypogonadal baseline to 22.3 +/- 5.6 nmol/L at 6 months). Luteinizing hormone levels decreased to within normal range in six patients and showed clinically significant decreases in four of the other seven patients (from 25 +/- 12 IU/L at hypogonadal baseline to 17 +/- 11 IU/L at 6 months). Nocturnal erections improved significantly during TTD system therapy in comparison with the hypogonadal state. Patient self-reported measures of sexual functioning were comparable to those during prior IM testosterone treatment and better than during the hypogonadal state. Hypogonadal symptoms decreased during TTD therapy in comparison with hypogonadal baseline. No clinically significant changes were noted in prostate volume, prostate-specific antigen, or lipid values. Three patients experienced anxiety or depression during TTD treatment, requiring discontinuation of therapy in one case and use of antidepressants in the other two. CONCLUSION: The testosterone patches were generally well tolerated in all patients. The nonscrotal TTD system for testosterone replacement is a safe and effective treatment for patients with Klinefelter's syndrome.

GLP-1 tablet in type 2 diabetes in fasting and postprandial conditions.

OBJECTIVE: To examine the absorption of glucagon-like peptide (GLP)-1(7-36) amide from the buccal mucosa of type 2 diabetic patients. Previously, the effects of the peptide have been studied following intravenous and subcutaneous injection. Now, a mucoadhesive, biodegradable buccal GLP-1 tablet (9 mm) containing 119 nmol has been developed as a possible alternative to injection. RESEARCH DESIGN AND METHODS: A total of 10 type 2 diabetic patients received a single tablet under fasting conditions and before a standard meal in this randomized placebo-controlled study. RESULTS: The mean peak GLP-1 concentration was 125.1 pmol/l and occurred 30 min after application. The mean placebo-adjusted area under the curve was 5,334 min pmol/l, consistent with a relative bioavailability of 6% vs. intravenous injection and 42% vs. subcutaneous injection. The half-life of total peptide activity after buccal administration was 17 min. The placebo-adjusted glucose concentrations decreased by 1.4 mmol/l in fasting experiments and by 4.2 mmol/l after a standard mixed meal. In the fasting state at 30 min, plasma insulin increased by 185% and glucagon decreased by 20%, consistent with the increase in plasma GLP-1 concentrations. The peptide exerted a significant insulinotropic effect during meals (calculated as an insulinogenic index, 0-120 min; 84.1 vs. 45.7 in placebo experiments). CONCLUSIONS: Potentially therapeutic plasma levels of GLP-1 were achieved after administration of a single buccal tablet in type 2 diabetic patients. The peptide had a marked glucose-lowering effect during the first 2 h. This new GLP-1 tablet may become a feasible alternative treatment for type 2 diabetic patients, although a more prolonged pharmacokinetic profile is required.

The effects of oral doses of lansoprazole and omeprazole on gastric pH.

We compared gastric pH values after therapeutic doses of lansoprazole and omeprazole in 17 healthy adult men. The pharmacokinetics of the two drugs were studied. A three-way crossover design compared the effects on gastric pH of 15 and 30 mg lansoprazole and 20 mg omeprazole--each given once daily for 5 days. Ambulatory 24-h intragastric pH levels were measured before dosing, after the first and fifth doses in each period, and 15 days after each dosing period. A positive relationship between the lansoprazole or omeprazole area under the curve (AUCs) and the 24-h mean pH values was found for each regimen. No differences in maximum concentration (Cmax) and AUC were noted from day 1 to day 5 for the two lansoprazole doses. With omeprazole, both Cmax and AUC levels were greater on day 5 than on day 1. All three regimens increased 24-h mean gastric pH, although 30 mg lansoprazole had the most significant effect. The percentage of time that gastric pH was >3, >4, and >5 was also significantly higher with 30 mg lansoprazole. All three regimens were associated with reversible elevations of serum gastrin, which more than doubled at some points. No clinically significant adverse events were documented.

Prostate size in hypogonadal men treated with a nonscrotal permeation-enhanced testosterone transdermal system.

OBJECTIVES: This study examined the effects of testosterone replacement using a nonscrotal testosterone transdermal (TTD) system on prostate size and prostate-specific antigen (PSA) levels in hypogonadal men. METHODS: As part of an open-label, multicenter study, prostate volume as measured by transrectal ultrasound and PSA were assessed in 29 hypogonadal men during treatment with intramuscular testosterone enanthate (+TE), followed by 8 weeks of androgen withdrawal (-T), and then during 1 year of therapy with Androderm Testosterone Transdermal System, a nonscrotal permeation-enhanced TTD system (+TTD). RESULTS: Mean prostate volume decreased significantly from the +TE period (17 g) compared with the -T period (14 g) (P < 0.001). Prostate volume increased significantly from the -T period compared with the +TTD period (18 g) (P < 0.001). Maximum prostate size, comparable to that measured during +TE (P = 0.125), was reached by month 3 of +TTD therapy; prostate volume did not increase further during the remaining 9 months of +TTD therapy. Prostate volume correlated with age (P < 0.01) during all three periods of observation (+TE: r = 0.69; -T: r = 0.64; and +TTD: r = 0.55). No patient developed symptomatic benign prostatic hyperplasia during the treatment period. PSA levels decreased during androgen withdrawal compared with levels measured during +TE treatment (P < 0.001) and rose with resumption of androgen therapy with TTD (P < 0.006). However, PSA levels during +TTD replacement remained significantly lower (P < 0.001) than during +TE replacement. CONCLUSIONS: Physiologic testosterone replacement in hypogonadal men was achieved using the TTD system. Prostate size during therapy with TTD was comparable to that reported for normal men. In these men treated with TTD, PSA levels were also within the normal range.

Long-term efficacy and safety of a permeation-enhanced testosterone transdermal system in hypogonadal men.

OBJECTIVE: An important aim in treating male hypogonadism is restoration of physiological concentrations of testosterone and its metabolites. We have assessed hormone levels, pharmacokinetics and clinical response, including safety, of a permeation-enhanced testosterone transdermal system (TTD) in the treatment of hypogonadal men for a 12-month period. DESIGN: Open-label, multicentre study with four consecutive periods: Period I (3 weeks)--evaluation of patients' current androgen therapy, which consisted primarily of testosterone enanthate injections (mean dose 229 mg; mean interval 26d); Period II (8 weeks)--androgen washout; Period III (3-4 weeks)--single-dose pharmacokinetic studies of TTD systems; Period IV (12 months)--efficacy, safety, and steady-state pharmacokinetic evaluation of TTD systems (5 mg/day nominal delivery rate of testosterone). Results from Periods I, II, and IV were compared. PATIENTS: Thirty-seven hypogonadal men 21-65 years old enrolled; 34 entered Periods III and IV; 29 (9 primary, 20 secondary hypogonadism) completed the study. Four patients withdrew because of adverse events (Period II, one; Period IV, three). MEASUREMENTS: Morning serum levels of total testosterone (T), bioavailable testosterone (BT), dihydrotestosterone (DHT), and oestradiol (E2) levels. Circadian pattern of T profiles and 24-hour time-average T level. LH levels in patients with primary hypogonadism. Reduction of hypogonadal symptoms. Safety assessments including skin tolerability, prostate parameters, lipid profile, and systemic parameters. RESULTS: Twelve months of TTD therapy normalized morning serum T levels in 93% of patients, and produced greater than 80% normalization of BT, DHT and E2 levels. The TTD system mimicked the circadian variation in T levels seen in healthy young men and normalized 24-hour time-average T levels in 86% of patients. Luteinizing hormone was suppressed in 8 of 9 men with primary hypogonadism, and normalized in 5 of these. Subjective symptoms of hypogonadism, including decreased libido and fatigue, showed improvement after 2-4 weeks of TTD treatment in most patients. The majority of adverse events were local skin reactions, and 3 patients (9%) discontinued the study for this reason. Prostate assessments showed a lower prostate-specific antigen level during TTD therapy compared to IM injections (0.66 vs 1.00 microgram/l P < 0.001), while prostate size did not differ significantly between the two treatment regimens. CONCLUSIONS: The permeation-enhanced testosterone transdermal system produces physiological levels and circadian patterns of testosterone, and its metabolites, in hypogonadal men. Although transient erythema and itching is commonly reported, the TTD is generally well tolerated by most patients. This system offers a new treatment option for testosterone replacement therapy that results in physiological serum levels of sex hormones in hypogonadal men.

Improvement of sexual function in testosterone deficient men treated for 1 year with a permeation enhanced testosterone transdermal system.

PURPOSE: The effects of androgen replacement via a nonscrotal permeation enhanced testosterone transdermal system on the sexual function of men with hypogonadism were assessed. MATERIALS AND METHODS: An open label, multicenter study of testosterone supplementation and withdrawal was conducted with sexual function assessed by the Watts and Davidson questionnaires and RigiScan monitoring. RESULTS: When comparing results obtained during use of the testosterone transdermal system (with normalized testosterone levels) and during the androgen withdrawal period, nocturnal erections occurred more frequently with longer duration and greater rigidity, and patient assessments of sexual desire and weekly number of erections were higher. CONCLUSIONS: Sexual function improved significantly in men with hypogonadism treated with the testosterone transdermal system.

Pharmacokinetics and metabolism of a permeation-enhanced testosterone transdermal system in hypogonadal men: influence of application site- -a clinical research center study.

As part of a phase III multicenter study, the pharmacokinetics and metabolism of a permeation-enhanced testosterone (T) transdermal (TTD) system and the influence of application site were investigated in 34 hypogonadal men (21-65 yr of age). After an 8-week androgen washout period, two TTD systems were applied to the back for 24 h. Serum concentrations of total T, bioavailable testosterone (BT), dihydrotestosterone (DHT), and estradiol (E2) increased from hypogonadal levels into the respective normal physiological ranges and declined to baseline levels within 24 h after system removal. Peak concentrations occurred approximately 8 h after application for T and BT and at 13 h for DHT and E2. The baseline-subtracted time-average steady state concentrations (C'ss) for T and BT were 18.1 +/- 7.49 (+/- SD) and 9.08 +/- 3.99 nmol/L, respectively. DHT/T and E2/T ratios, derived from the C'ss values, were 0.063 +/- 0.018 and 0.0033 +/- 0.0018, comparable to the precursor-product conversion ratios reported in healthy men. The estimated half-lives of each hormone were: T, 1.29 +/- 0.71 h; BT, 1.21 +/- 0.75 h; DHT, 2.83 +/- 0.97 h; and E2, 3.53 +/- 1.93 h. The influence of application site was then evaluated by applying two TTD systems for 24 h to the abdomen, back, chest, shin, thigh, or upper arm, according to a sequential cross-over design. Hormone profiles were qualitatively similar at each site, but C'ss values showed significant differences (by ANOVA, P < 0.0001). Based on the BT levels, the rank ordering of the sites were: back > thigh > upper arm > abdomen > chest > shin. DHT/T and E2/T ratios showed negligible site to site variation and were comparable to the results from the initial study. Estimates of T input, based on hormone levels and analysis of the systems used, averaged 4-5 mg/day for the abdomen, back, thigh, and upper arm and were lower and more variable for the chest and shin. Individual C'ss values for T and BT increased linearly with the T input rates (derived from used system analysis) across all studies (n = 235; r = 0.564 for T and r = 0.754 for BT). From these data, T and BT clearance rates were estimated for each patient, averaging 1248 +/- 518 and 2435 +/- 778 L/day, respectively. T clearance rates were proportional to the BT/T ratio (nonsex hormone-binding globulin-bound fraction). On the basis of these studies, the optimal sites of TTD system application were identified as the back, thigh, upper arm, and abdomen

Pathogenesis and treatment of acid peptic disorders: comparison of proton pump inhibitors with other antiulcer agents.

Acid peptic disorders, including gastric ulcers, duodenal ulcers, and gastroesophageal reflux disease, are commonly occurring conditions with high direct and indirect costs. The pathogenesis of these disorders involves an imbalance between acid secretion and gastric mucosal defenses. Pharmacologic treatment of acid peptic disorders has focused on correcting this imbalance by either improving mucosal defenses with drugs such as sucralfate, bismuth, and prostaglandin analogs, neutralizing acid with antacids, or decreasing acid secretion with histamine2 (H2)-receptor antagonists, or, more recently, proton pump inhibitors. Proton pump inhibitors are more potent inhibitors of acid secretion than H2-receptor antagonists. In clinical comparisons, proton pump inhibitors were shown to be more effective in the treatment of acid peptic disorders than H2-receptor antagonists. Helicobacter pylori infection is a factor in 85% to 100% of duodenal ulcers and 70% to 90% of gastric ulcers; eradicating this organism results in a considerable decrease in the recurrence of ulcers. Current management of peptic ulcer disease includes the use of combination antisecretory and antibiotic therapy for acute treatment of H pylori-associated disease. Patient self-medication with over-the-counter products, including H2-receptor antagonists, may have an impact on the potential for reducing the recurrence of peptic ulcer disease in patients with H pylori infection. Patients with recurrent disease should be informed of the need to seek medical treatment through aggressive education at the point of sale for over-the-counter drugs.

The pharmacokinetics of recombinant human relaxin in nonpregnant women after intravenous, intravaginal, and intracervical administration.

The pharmacokinetics of recombinant human relaxin (rhRlx) after intravenous (iv) bolus administration and the absorption of rhRlx after intracervical or intravaginal administration were determined in nonpregnant women. The study was conducted in two parts. In part I, 25 women received 0.01 mg/kg rhRlx iv. After a minimum 7-day washout period, these women were dosed intracervically (n = 10) or intravaginally (n = 15) with 0.75 or 1.5 mg rhRlx, respectively, in 3% methylcellulose gel. Part II was a double-blind, randomized, three-way crossover study in 26 women. At 1-month intervals, each woman received one of three intravaginal treatments consisting of 0 (placebo), 1, or 6 mg rhRlx in 3% methylcellulose gel. The serum concentrations of relaxin following iv administration were described as the sum of three exponentials. The mean (+/- SD) initial, intermediate, and terminal half-lives were 0.09 +/- 0.04, 0.72 +/- 0.11, and 4.6 +/- 1.2 hr, respectively. Most of the area under the curve was associated with the intermediate half-life. The weight-normalized clearance was 170 +/- 50 mL/hr/kg. The observed peak concentration was 98 +/- 29 ng/mL, and the weight-normalized initial volume of distribution was 78 +/- 40 mL/kg, which is approximately equivalent to the serum volume. If central compartment elimination was assumed, the volume of distribution at steady state (Vss/W) was 280 +/- 100 mL/kg, which is approximately equivalent to extracellular fluid volume. Vss/W could be as large as 1300 +/- 400 mL/kg without this assumption.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of lansoprazole, a new H+,K(+)-ATPase inhibitor, on gastric pH and serum gastrin.

This study examined the effects of dose and time of administration of lansoprazole on gastric pH and serum gastrin in healthy male volunteers. Three groups of six subjects received 10, 20 or 60 mg doses of lansoprazole or placebo. Doses were administered at 22.00 hours daily for 7 days. An additional 18 subjects received once daily 30 mg oral doses of lansoprazole or placebo; these subjects were dosed at either 08.00 hours or 22.00 hours in a randomized, crossover fashion with a 2-week washout period. Gastric pH was monitored for 24 h following the first and final dose, and 1 week following the completion of dosing. Lansoprazole, at all doses except 20 mg/day, significantly increased the median 24-hour gastric pH following 7 days of dosing (P less than 0.05). In addition, morning dosing in the 30-mg crossover group led to a higher 24-h median pH than evening dosing (P = 0.003). There was no difference in night-time median pH between morning and evening dosing. Morning dosing also led to a significant increase in gastric pH on study Day 1 (P less than 0.05). Plasma concentrations of lansoprazole were highly variable between subjects, but there was a significant correlation between AUC and the median 24-h gastric pH. Plasma concentrations and AUCs were higher on Day 7 than on Day 1 for subjects receiving 10 or 20 mg, but not for those receiving 30 or 60 mg doses. Lansoprazole bioavailability demonstrated a circadian effect manifested by higher plasma concentrations following morning dosing. Serum gastrin concentrations were elevated in all active medication groups.

Effect of a single dose of lactase on symptoms and expired hydrogen after lactose challenge in lactose-intolerant subjects.

The effect of a single dose or oral lactase on symptoms, breath hydrogen concentration, and glucose absorption in lactose-intolerant subjects challenged with lactose was studied. Volunteers underwent a lactose challenge test; those whose breath hydrogen concentrations increased 20 ppm or more and who met other criteria were admitted as subjects. After fasting, the subjects were given three chewable lactase tablets (total lactase dose, 9900 FCC units) or placebo tablets in a randomized, double-blind, crossover manner. The subjects also consumed 8 oz of whole milk in which 37.5 g of lactose powder was dissolved (total lactose content, 50 g). The washout period between lactose challenges was at least one week. Breath hydrogen and plasma glucose concentrations were measured before and at intervals after the challenges, and the subjects completed symptom-evaluation questionnaires every eight hours for four days. Twenty-four subjects completed the study. The maximum mean breath hydrogen concentration was significantly lower after lactase treatment than after placebo treatment. In 21 subjects, the area under the hydrogen concentration-time curve (AUC) was lower after lactase than after placebo; three subjects had hydrogen AUCs more than 300 ppm.hr lower. There were no significant differences in plasma glucose levels. Subjective ratings of the severity of abdominal cramping, belching, flatulence, and diarrhea were lower during the first eight hours after challenge in lactase-treated subjects; ratings for bloating were lower during the next eight hours. Single doses of a chewable lactase tablet reduced the concentration of expired hydrogen and symptoms of lactose intolerance after a lactose challenge.

Circadian differences in pharmacological blockade of meal-stimulated gastric acid secretion.

The effects of identical morning (08.05 hours) and evening (20.05 hours) meals on intragastric pH were compared in 12 healthy volunteers receiving gastric antisecretory medication. Dosing included continuous intravenous infusion ranitidine (50 mg bolus followed by 12.5 mg/h) or a matching placebo which were randomly administered prior to and following 7 days of treatment with oral omeprazole (40 mg mane). Intragastric pH was monitored continuously using a tethered indwelling pH probe. Subjects were divided into groups, one of which began the pH monitoring session in the morning, the other in the evening. The median 24-h intragastric pH was significantly increased by all active dosing regimens (P less than 0.05). Combined omeprazole and ranitidine produced the highest median pH, 5.92. However, a breakthrough drop in intragastric pH occurred during the evening after all active dosing. Intragastric pH fell prior to and after consumption of the evening meal with median pH values less than 4 during all sessions. The evening meal led to significantly lower intragastric pH compared to the morning meal for omeprazole and the combined omeprazole and ranitidine dosing periods (P less than 0.05). There was no difference between morning and evening pH during the placebo or ranitidine periods. Ranitidine and omeprazole, either alone or in combination, were unable to prevent the meal-stimulated decline in intragastric pH during the evening time period.

Enhanced transdermal delivery of testosterone across nonscrotal skin produces physiological concentrations of testosterone and its metabolites in hypogonadal men.

None of the current or experimental androgen treatment modalities for male hypogonadism has been reported to produce physiological concentrations or circadian variations in testosterone (T) and its metabolites, dihydrotestosterone (DHT) and estradiol (E2). This investigation describes a novel transdermal dosage form designed to enhance the delivery of native T across nonscrotal skin. The main objective was to determine whether the nightly application of two experimental transdermal patches to different sites on the body (e.g. back, chest, arms, etc.) would result in normal plasma levels of T, DHT, and E2 for men and mimic the normal circadian variation. Six hypogonadal males (aged 24-66 yr) were studied 4 weeks after stopping T ester treatment. After single application of two patches, T levels increased from a pretreatment baseline of 5.8 +/- 0.94 nmol/L (mean +/- SE; 167 +/- 27 ng/dL) to an average peak concentration of 44.1 +/- 4.8 nmol/L (1273 +/- 138 ng/dL) 5.7 +/- 0.6 h after application and reached a 24-h level of 16.9 +/- 2.9 nmol/L (488 +/- 85 ng/dL). DHT and E2 levels exhibited parallel variations within the normal reference ranges. During 4 weeks of daily evening application to various sites on the torso, the mean delivery of T from two patches was 5.2 +/- 0.1 mg/day (approximately 20% of the patch content), and morning T levels were within the normal limits. On day 28 of treatment, the 24-h plasma profiles of T, DHT, and E2 (obtained with two patches on the back) approximately mimicked the normal circadian variations reported in healthy young men. The time-averaged T level was 21.8 +/- 2.9 nmol/L (629 +/- 84 ng/dL), and the plasma concentration ratios of DHT/T (0.07 +/- 0.01) and E2/T (0.005 +/- 0.001) were within the normal range. SHBG concentrations were not significantly altered over the 4 weeks of treatment. The patches were well tolerated, except for one patient who developed a local reaction to an excipient during the third week of treatment. Two of the patients (one with Klinefelter's syndrome) completed several months of continuous therapy. T, DHT, and E2 have remained in the range of normal, and plasma LH levels in the patient with Klinefelter's syndrome became normal. Subjective improvement in symptoms has continued, and tolerability has been good in both patients. These results indicate that the enhanced transdermal delivery of T across nonscrotal skin is a patient-friendly androgen replacement modality and produces physiological concentrations of T and its metabolites, which are unattainable with other treatment modalities.

Gastrointestinal chronopharmacology: physiology, pharmacology and therapeutic implications.

This chapter discusses the influence of ultradian and circadian rhythms of gastrointestinal motor and secretory function on the action of orally administered drugs. Most drugs exhibit more rapid absorption in the morning compared to the evening due, in part, the circadian alterations in gastric emptying. Gastric acid secretion and gastrointestinal toxicity to oral drugs also display circadian rhythmicity. These observations provide a rationale for use or avoidance of drugs based on time-of-day dosing considerations. The chronopharmacological behavior of a drug may thus play an important role in the effectiveness of any oral medication treatment schedule.

Single-dose pharmacokinetics and tolerance of a cholesteryl sulfate complex of amphotericin B administered to healthy volunteers.

Twenty-three healthy volunteer subjects received a single dose of amphotericin B colloidal dispersion or placebo (4:2) in a double-blind, randomized, dose-escalating design. Doses ranged from 0.25 to 1.5 mg/kg of body weight. The medication was administered via intravenous infusion at a rate of 0.5 mg/kg/h. Plasma amphotericin B concentrations increased with increasing doses, resulting in a linear increase in the amphotericin B area under the curve. Concentrations in plasma decreased rapidly upon discontinuation of the infusion, indicating rapid tissue distribution. A log-linear biexponential elimination phase was observed. A three-compartment open model was used to describe the distribution and elimination of amphotericin B. The mean terminal elimination half-life ranged from 86 h at the 0.25-mg/kg dose level to 244 and 235 h at the 1.0- and 1.5-mg/kg dose levels, respectively. Mean total body clearance ranged from 219 to 284 ml/kg/h. The volume of distribution increased with dose, from 3.37 liter/kg at the 0.25-mg/kg dose to 7.92 liter/kg at the 1.5-mg/kg dose. At the lowest dose level, 0.25 mg/kg, the medication was generally well tolerated. Progressive increases in the dose led to increasing side effects. At the 1.5-mg/kg dose level, 50% of the patients on active medication experienced nausea, vomiting, and chills. Physical examinations, ophthalmologic examinations, and clinical laboratory parameters remained within normal limits compared with those obtained during prestudy examinations.