Plasma prednisolone levels in man following administration in plain and enteric-coated forms.

1 Prednisolone plasma levels were measured in seven patients by a competitive protein binding method after administration of prednisolone (20 mg) by mouth as plain or enteric-coated tablets. 2 The mean peak plasma prednisolone concentration after the enteric-coated preparation, 199 ng ml-1, was significantly lower than after the plain tablet, 268 ng ml-1, and occurred later, at 4.69 h compared with 1.72 h. The bioavailability of the two preparations was similar. 3 It is concluded that, although the plasma concentration versus time profiles are different, the absorption of prednisolone from plain and enteric-coated preparations is equal.     

Variation in plasma prednisolone concentrations in renal transplant recipients given enteric-coated prednisolone.

Renal transplant recipients receiving intermittent haemodialysis and kept under normal ward conditions showed appreciable differences in plasma prednisolone concentrations after therapeutic doses of enteric-coated prednisolone tablets. This gross day-to-day variation occurred irrespective of the dosage used. Breakfast given before prednisolone tended to reduce the rate of absorption of the drug, the effect being quantitatively most pronounced with large doses. Haemodialysis had no apparent effect on the elimination of prednisolone from plasma. Such erratic blood concentrations of prednisolone as observed in these patients, possibly resulting from variable absorption, may be potentially hazardous. Hence use of enteric-coated tablets in renal transplant recipients should be viewed with caution.     

Absorption of quinidine from an enteric-coated preparation

Summary The absorption of quinidine from single and multiple doses of an enteric-coated preparation (Systodin^?) was studied in seven healthy subjects, and was compared with the pharmacokinetics of intravenously administered quinidine and the results of in vitro dissolution tests of the tablets. Absorption of quinidine began after a variable delay, 2–8 h (mean 4.8) after fasting and 3–10 h (mean 6.1) after food. The rate of absorption varied both in and between individuals. It appeared to be lower when the drug was administered after food. Multiple doses after food gave a pattern of plasma concentration-time curves similar to that found on administration of single doses after food. The delay prior to absorption was prolonged at night. The ratio between the maximum and minimum concentration of quinidine during a dose interval varied from 1.3 to 3.2 (mean 2.0). Bioavailability of quinidine in fasting subjects ranged from 69 to 95% (mean 83); variation was greater when doses were administered after food. The release of quinidine from the enteric-coated preparation was pH dependent and was sustained at low pHs as may be found in the intestines. The results indicate that the absorption of quinidine from the enteric-coated formulation was dependent on the highly variable rate of gastric emptying and the pH of intestinal fluid, and it varied greatly both within and between individuals.     

A pharmacokinetic and pharmacodynamic comparison of plain and enteric-coated prednisolone tablets.

1. Eight healthy volunteers and eight patients suffering from chronic obstructive pulmonary disease (COPD) received 30 mg prednisolone as plain (P) and enteric-coated tablets (EP) in a randomised, cross-over manner. Plasma prednisolone and cortisol and blood glucose were measured over 24 h. 2. Although absorption of prednisolone was considerably slower when administered as the enteric-coated form, peak plasma drug concentrations and total AUC (0,24 h) were equivalent for the two formulations. Malabsorption of prednisolone was not observed. 3. The administration of EP was associated with significantly less adrenal suppression in volunteers than P as judged by measurement of AUC (0,24 h) values for endogenous cortisol. However, this difference did not reach statistical significance in the patient group. 4. Plasma cortisol concentrations declined more slowly following administration of the enteric-coated form to both groups. The difference in time taken (median and range) to maximum suppression of cortisol was statistically significant (P less than 0.05) between P (2.5 h; 2-4 h) and EP (4 h; 3-12 h) preparations administered to volunteers. There was a similar significant difference (P less than 0.05) between P (2.5 h; 1-4 h) and EP (7 h; 2-12 h) in the patients. 5. Plasma cortisol concentrations were significantly lower at 24 h in patients receiving the enteric-coated product in association with higher terminal prednisolone concentrations. 6. Blood glucose concentrations increased over an 8 h period in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

单硝酸异山梨酯阿司匹林缓释片在人体内的药动学及生物等效性

20名健康受试者随机交叉单剂量(单硝酸异山梨酯60mg和阿司匹林75mg)和多剂量口服单硝酸异山梨酯阿司匹林缓释片(受试制剂)、单硝酸异山梨酯缓释片及阿司匹林肠溶片(参比制剂)后,分别采用HPLC-MS法和HPLC-UV法测定人血浆中单硝酸异山梨酯和水杨酸浓度。药动学参数见文中表1和表2。经双单侧t检验结果表明,以单硝酸异山梨酯为研究对象,两制剂具有生物等效性;以阿司匹林为研究对象,两制剂的吸收程度相当,但受试制剂吸收速度较快。     

两种盐酸二甲双胍制剂的吸收比较

目的比较两种盐酸二甲双胍制剂在人体内的吸收。方法采用RP-HPLC法测定两种制剂给药后的血药浓度。结果在测定方法与给药量相同的情况下,肠溶片的血药浓度数据不完整。结论肠溶片在胃肠道的吸收不完全。     

Influence of food on the absorption of acetylsalicylic acid from enteric-coated dosage forms

Summary The absorption of acetylsalicylic acid (ASA) from two different enteric-coated dosage forms, tablets (Premaspin) and granules (Reumyl^®), was studied in healthy volunteers under fasting and non-fasting conditions by following the plasma concentration and urine recovery of salicylates after single doses of ASA 1 g. Conventional tablets (Aspirin^®) were used as the reference. Under fasting conditions the absorption of ASA from the two different enteric-coated preparations was complete. Taken with food the enteric-coated tablets gave much lower plasma concentrations than under fasting conditions, and absorption was not complete in all subjects. In contrast, absorption from the enteric-coated granules was not influenced by the intake of food. It was concluded that enteric-coated granules of ASA permit more reproducible absorption than enteric-coated tablets.     

Relative systemic availability of sulfapyridine from commercial enteric-coated and uncoated sulfasalazine tablets.

The absorption of sulfapyridine after a single 2.0-Gm oral dose of sulfasalazine, the drug of choice in the treatment of inflammatory bowel disease, as commercial uncoated and enteric-coated and uncoated tablets was evaluated in four healthy male adults. The peak plasma concentration of sulfapyridine after the enteric-coated tablets occurred at 20 hours on the average (compared to 14 hours for the uncoated tablets) and was only 50% of that attained from the uncoated tablets (P less than 0.05). The low relative extent of systemic availability of sulfapyridine from the enteric-coated tablets (65.5 +/- 6.3 per cent, mean +/- S.E.) compared to uncoated tablets may be due to absorption rate-dependent presystemic metabolism, since the relative extent of sulfapyridine absorption was 92.7 +/- 6.2 per cent compared to uncoated tablets. These findings suggest that enteric-coated and uncoated tablets of sulfasalazine are not bioequivalent. It remains to be determined whether the clinical efficacy of sulfasalazine from enteric-coated tablets is affected.     

Enhancement of ursodeoxycholic acid bioavailability by cross-linked sodium carboxymethyl cellulose

The bioavailability of ursodeoxycholic acid from a new formulation based on drug-loaded cross-linked sodium carboxymethyl cellulose was studied in man. The plasma levels of ursodeoxycholic acid were determined by gas chromatography-mass spectrometry after derivatization and sample purification by solid-phase extraction. Capsules containing the drug/polymer system were prepared and compared with conventional commercial ursodeoxycholic acid capsules after single oral administration using a randomized crossover experimental design. Although the drug/polymer system improved the in-vitro dissolution rate of ursodeoxycholic acid in simulated intestinal fluid, statistical evaluation of the area under the plasma concentration curves indicated no significant difference in the extent of bioavailability between the two formulations (14.93+/-4.43 vs 14.95+/-5.79 microM h; P > 0.2). However, following the administration of the ursodeoxycholic acid/cross-linked sodium carboxymethyl cellulose system with an enteric-coated capsule, the mean area under the plasma concentration curve (27.60+/-10.11 microM h) was significantly higher than that obtained after treatment with the commercially available ursodeoxycholic acid capsule (16.24+/-8-38 microM h; P < 0.05). We concluded that improved intestinal absorption of the drug was obtained with enteric-coated capsules filled with the ursodeoxycholic acid/polymer system. Moreover, the simplicity of the preparation and the non-toxicity of the polymer used as the carrier represented additional advantages of this dosage form.     

Plasma prednisolone levels from enteric and non-enteric coated tablets estimated by an original technique.

1 A quantitative thin layer chromatographic technique for the estimation of plasma prednisolone levels has been devised with a minimum level of estimation of 10 ng/ml. 2 A comparative study of the absorption of 5 and 10 mg prednisolone from enteric and non-enteric coated tablets (5 mg) was carried out in healthy subjects. 3 Mean plasma half-life and peak plasma concentrations obtained from the non-enteric coated preparation agree well with previous studies in normal subjects reported by other investigators using competitive protein binding or radioimmunoassay techniques. Intersubject variability in bioavailability was noted. 4 Enteric coating increased the lag time before prednisolone appeared in the blood but did not alter the bioavailability of prednisolone compared to the equivalent dose of the non-enteric coated tablet.     

EPILIM® CHRONO: A MULTIDOSE,CROSSOVER COMPARISON OF TWO FORMULATIONS OF VALPROATE IN HEALTHY VOLUNTEERS

The pharmacokinetic properties and relative bioequivalence of two formulations of the antiepileptic Epilim® were compared in a three-period, repeat dose, randomized crossover study in 18 male volunteers. A daily dose of 1000 mg of antiepileptic was given either as twice-daily enteric-coated sodium valproate tablets or as twice- or once-daily controlled release tablets (Epilim® Chrono, sodium valproate/valproic acid mixture). All regimens were bioequivalent with respect to area under the curve and elimination half-life. The twice-daily controlled release formulation showed reduced mean peak plasma valproate levels and raised mean trough levels compared with the enteric coated tablets. The once-daily controlled release regimen gave reduced mean peak levels but similar mean trough levels to the twice-daily enteric-coated regimen. No major differences between regimens were observed in the time at which peak concentration was observed. Both formulations were well tolerated. The most frequently reported adverse event was mild diarrhoea (all on Chrono treatment) which is probably related to the lack of enteric coating on this formulation. The reduced mean peak--trough variation in plasma valproate levels observed with the twice-daily controlled release regimen is likely to reduce further the low incidence of concentration-related side-effects with sodium valproate and permit more reliable plasma level monitoring. This study also indicates that once-daily treatment with Epilim® controlled release would be a suitable replacement for twice-daily dosing with either formulation. Once-daily treatment is likely to give considerable benefits both in convenience and in better patient compliance.     

双氯芬酸缓释片的生物利用度研究

以ＨＰＭＣ为主要辅料制备双氯芬酸缓释片。其溶出符合零级动力学模型，ｔ１／２＝２６３．９５ｍｉｎ，而国产肠溶衣片ｔ１／２＝７４．５８ｍｉｎ。８名健康志愿受试者交叉口服自制缓释片及肠溶衣片各１００ｍｇ后测定血药浓度，结果表明两者起效速度和生物利用度无显著差异，而消除半衰期前者明显大于后者。     

Pharmacokinetics of salicylic acid following administration of aspirin tablets and three different forms of soluble aspirin in normal subjects

The pharmacokinetic profile of an innovative formulation of soluble aspirin (l-ornithine acetylsalicylate, ldB 1003) was compared with that of conventional tablets and two other soluble dosage forms (d, l-lysine acetylsalicylate and a buffered effervescent formulation of acetylsalicylic acid) after administration of single oral doses in six normal volunteers. All soluble forms showed a rapid absorption profile, peak plasma salicylic acid levels being attained after about 30 min on average and without statistically significant differences among the solutions tested. As compared to the soluble formulations, acetylsalicylic acid given as tablets resulted in slower absorption, with peak plasma salicylic acid levels being reached more than 1 h after dosing. Despite these differences in time course of plasma level profiles, the extent of absorption was similar for all formulations. Apart from the potential advantages in terms of improved gastric tolerability, the increased rate of absorption of aspirin solutions is therapeutically useful whenever a rapid onset of action is required. In this respect, the kinetic pattern of the innovative formulation compares favourably with that of other available soluble dosage forms.     

Profiling biopharmaceutical deciding properties of absorption of lansoprazole enteric-coated tablets using gastrointestinal simulation technology

The aim of the present study was to correlate in vitro properties of drug formulation to its in vivo performance, and to elucidate the deciding properties of oral absorption. Gastrointestinal simulation technology (GST) was used to simulate the in vivo plasma concentration–time curve and was implemented by GastroPlus™ software. Lansoprazole, a typical BCS class II drug, was chosen as a model drug. Firstly, physicochemical and pharmacokinetic parameters of lansoprazole were determined or collected from literature to construct the model. Validation of the developed model was performed by comparison of the predicted and the experimental plasma concentration data. We found that the predicted curve was in a good agreement with the experimental data. Then, parameter sensitivity analysis (PSA) was performed to find the key parameters of oral absorption. The absorption was particularly sensitive to dose, solubility and particle size for lansoprazole enteric-coated tablets. With a single dose of 30 mg and the solubility of 0.04 mg/ml, the absorption was complete. A good absorption could be achieved with lansoprazole particle radius down to about 25 μm. In summary, GST is a useful tool for profiling biopharmaceutical deciding properties of absorption of lansoprazole enteric-coated tablets and guiding the formulation optimization.     

中药宫灵肠溶片的制备及其质量控制

目的：研究宫灵肠溶片的制备工艺和质量控制方法。方法：采用TLC法对处方中的黄芪进行了定性;用高效液相色谱法测定了黄芪甲苷的含量。结果：定性鉴别分离度好,专属性强,含量测定黄芪甲苷的平均回收率为97.19%,RSD为1.39%。结论：本制备工艺合理可行,质量控制方法重现性好,能有效地控制该制剂的质量。     

Enteric-coated tablets improve oral bioavailability of DX-9065, a novel anticoagulant

Oral bioavailability of DX-9065, a factor Xa inhibitor, was only 3% when it was administered as a conventional capsule formulation in fasted humans, and was further reduced to about one-tenth when it was administered to fed humans. The poor absorption of DX-9065 probably resulted from its low membrane permeability and its electrostatic interaction with bile acid. We designed enteric-coated tablets with the expectation that this pharmaceutical technology will prevent DX-9065 from interacting with bile acid. More than 85% of DX-9065 was released from the tablet coated with hypromellose acetate succinate within 10 min in simulated intestinal fluid (pH 6.8). Monkey experiments demonstrated that AUC of DX-9065 after oral administration of its enteric-coated tablet was about 5 times that of its aqueous solution in the fasted state. The food effect on drug absorption was also reduced when DX-9065 was administered as an enteric-coated tablet. The average ratio of AUC in a fed state to that in a fasted state was approximately 0.5, even though the ratio was 0.1 when the enteric-coated tablet was substituted with the drug solution. Enteric coating could be a useful method for improving oral absorption of DX-9065 with reduced food effects on drug absorption.     

Bioavailability of indomethacin from two multiple-units controlled-release formulations

Summary Two multiple-units controlled-release indomethacin capsule formulations containing enteric-coated pellets were bioequivalent to a standard capsule formulation (taken as the reference) in respect of extent of bioavailability in a crossover study with normal human subjects. However, drug absorption from the enteric-coated pellet formulations was slower, when compared to that from the standard reference capsule. The standard reference capsule released 85% of its drug content in vitro during 10 min at pH 6.5 and 98% during 1 h at pH 7.5. One enteric-coated pellet capsule formulation (I) released 77% during 1 h at pH 6.5 and the other (II) released 10% during 1 h at pH 6.5. Release of drug from each capsule of enteric-coated pellets was complete during 1 h at pH 7.5. Although differences in areas under the plasma indomethacin concentration-time curves were not significantly different, the peak plasma levels and the times of their occurrence indicated that the absorption rates of indomethacin decreased in the order, reference formulation > pellet formulation I > pellet formulation II, which was the same rank order as that of their dissolution rates in vitro. The data indicated that multiple units controlled-release formulations represent a reliable and reproducible source of indomethacin, which by avoiding extremes of local or systemic drug concentrations also should be better tolerated by individuals susceptible to unwanted gastrointestinal and centrally-mediated side-effects.     

Sulodexide oral administration influences blood viscosity and fibrinolysis.

The aim of this study was to verify the effects of oral administration of a new enteric-coated formulation of sulodexide on blood viscosity and fibrinolysis. Six outpatients suffering from peripheral artery occlusive disease were administered orally two enteric-coated tablets containing 50 mg of sulodexide, twice daily for seven days. On the first and seventh administration days, the following parameters were evaluated: plasminogen activator inhibitor (PAI-1) activity, PAI-1 antigen, tissue plasminogen activator (t-PA) and whole blood, serum and plasma viscosity, before (0 time) and 2, 4 and 8 hours after ingestion of the drug. Following the first administration (50 mg), a slight reduction of PAI was registered; after 7 days' administration, a clear-cut lowering of functional and antigenic PAI was observed, together with an increase of t-PA. As to the drug's influence on blood viscosity, after 7 days the most evident reduction was that registered for plasma viscosity. No side effects were observed throughout the treatment period.     

The pharmacokinetics of beta-methyl digoxin compared with digoxin tablets and capsules

Summary The intestinal absorption and urinary elimination rate of total cardioactive material was compared following digoxin and beta-methyldigoxin (BMD) administration to twelve healthy volunteers. Significantly more injected digoxin was recovered in urine. Urinary clearance was more rapid for digoxin, mean half-lives of elimination being 35 hours for digoxin and 40 hours for BMD. Calculated percentage intestinal absorption was lowest for digoxin tablets with a dissolution rate of 77% in one hour, intermediate for BMD tablets, and maximal for an experimental soft gelatin formulation of digoxin in solution. Respective mean values were 75%, 87% and 97%. Similar steady state plasma concentrations followed twice daily ingestion of the 0.25 mg digoxin tablets and 0.20 mg BMD tablets. Mean peak plasma concentration and percentage urinary recovery of ingested dose were higher during continued BMD administration. Between-subject variation in absorption was higher for the digoxin tablets. The comparative intestinal absorption of BMD and digoxin depends upon the formulation. Digoxin is virtually completely absorbed from a solution encapsulated in soft gelatin. Relatively more BMD is eliminated by nonrenal routes.