Prolongation of the gastric residence time of caffeine after administration in fed state: Comparison of effervescent granules with an extended release tablet

The aim of the present study was to investigate the gastroretentive capacity of different formulation principles. This was indirectly determined by the absorption behavior of caffeine from the dosage forms. A slow and continuous appearance of caffeine in the saliva of healthy volunteers was used as a parameter for a prolonged gastric retention time. For this purpose, a four-way study was conducted with twelve healthy volunteers using the following test procedures: (1) Effervescent granules with 240 mL of still water administered in fed state, (2) effervescent granules with 20 mL of still water in fed state, (3) extended release (ER) tablet with 240 mL of still water in fed state, and (4) effervescent granules with 240 mL of still water in fasted state. The initial rise of the caffeine concentrations was more pronounced after the intake of the effervescent granules in the fed state compared to that of the ER tablets. However, tmax tended to be shorter in the fed study arms following administration of the ER tablet compared to the granules. Overall, the application of active pharmaceutical ingredients formulated as effervescent granules seems to be a promising approach to increase their gastric residence time after intake in fed state.

Predicting gastric emptying of drug substances taken under postprandial conditions by combination of biorelevant dissolution and mechanistic in silico modeling

Physiologically based pharmacokinetic (PBPK) models can help to understand the effects of gastric emptying on pharmacokinetics and in particular also provide a platform for understanding mechanisms of food effects, as well as extrapolation between different postprandial conditions, whether standardized clinical or patient-oriented, non-clinical conditions. By integrating biorelevant dissolution data from the GastroDuo dissolution model into a previously described mechanistic model of fed-state gastric emptying, we simulated the effects of a high-calorie high-fat meal on the pharmacokinetics of sildenafil, febuxostat, acetylsalicylic acid, theobromine and caffeine. The model was able to simulate the variability in Cmax and tmax caused by the presence of the stomach road. The main influences investigated to affect the gastric emptying process were drug solubility (theobromine and caffeine), tablet dissolution rate (acetylsalicylic acid) and sensitivity to gastric motility (sildenafil and febuxostat). Finally, we showed how PBPK models can be used to extrapolate pharmacokinetics between different prandial states using theobromine as an example with results from a clinical study being presented.

Intragastric Carbon Dioxide Release Prolongs the Gastric Residence Time of Postprandially Administered Caffeine

Sparkling water is said to increase gastric motility by the release of carbon dioxide, thereby potentially affecting the pharmacokinetics of orally administered drugs. The hypothesis of the present work was that the induction of gastric motility by intragastric release of carbon dioxide from effervescent granules could promote the mixing of drugs into the chyme under postprandial conditions, resulting in a prolonged drug absorption. For this purpose, an effervescent and a non-effervescent granule formulation of caffeine as a marker for gastric emptying were developed. In a three-way crossover study with twelve healthy volunteers, the salivary caffeine pharmacokinetics, after administration of the effervescent granules with still water and the administration of the non-effervescent granules with still and sparkling water, were investigated after intake of a standard meal. While the administration of the effervescent granules with 240 mL of still water led to a significantly prolonged gastric residence of the substance compared to the administration of the non-effervescent granules with 240 mL still water, the application of the non-effervescent granules with 240 mL sparkling water did not prolong gastric residence via mixing into caloric chyme. Overall, the mixing of caffeine into the chyme following the administration of the effervescent granules did not seem to be a motility mediated process.

[Effects of sevoflurane versus propofol on oculocardiac reflex--a comparative study in 180 children]

Oculocardial reflex (OCR) occurs particularly through manipulation of the medial rectus muscle and results in a bradycardic arrhythmia. In children the incidence is between 60 and 80%. After using sevoflurane in clinical practice, the absence or non-occurrence of this reflex was observed. The data of 180 healthy children aged between four and 14 years who had to undergo strabismus surgery under general anaesthesia were analysed: group I (n = 92), group II (n = 88). All children received standard premedication with midazolam, no anticholinergic drugs were administered. During narcosis, analgesia was maintained routinely with alfentanil. In group I sevoflurane was inhaled for hypnosis and in group II propofol was injected as intravenous hypnotic drug. The depth of anaesthesia was adjusted according to clinical criteria. To compare both groups, heart rate (HR) was determined before, during and after surgical intervention. OCR was defined as a heart rate declining by more than 20% from the initial HR.OCR is described in all methods of general anaesthesia. Under sevoflurane the occurrence of the reflex was significantly (p < 0.05) reduced to 14% of all patients as compared to 75% in patients who received a propofol infusion. Sufficient reflex reduction according to the depth of narcosis under sevoflurane in combination with the sympathomimetic effects of this drug could therefore be discussed as a reason for its positive effects. In our opinion, the use of sevoflurane should be considered as an option for general anaesthesia in strabismus surgery.

[Ophthalmic surgery with local anesthesia or intubation anesthesia at the Leipzig University Ophthalmology Clinic]

BACKGROUND

Different opinions about the reliability and serious complications after regional anesthesia have been reported. The paper describes our experiences in deciding about regional or general anesthesia for ophthalmic surgery.

PATIENTS AND METHODS

For this report we analyzed retrospectively our protocols of all operations performed in 1995. Eight categories of procedures were developed to give an insight in our way of decision for local or general anesthesia. We imagine the applied technique of peribulbaranesthesia.

RESULTS

3184 patients were operated on in 1995, in the regional anesthesia group the age ranges from 17 to 96 years, in the general anesthesia group from 3 months to 85 years. In 69.9% of all patients we performed a local anesthesia and in 30.1% we chose general anesthesia. The spread of cases and the surgical procedure corresponding to one of these eight classes below are described in this survey.

CONCLUSIONS

Almost 70% of our patients who underwent an ophthalmosurgical procedure were operated on under regional anesthesia. No serious complications have occurred and no procedure had do be stopped off due to an insufficient analgesia or akinesia. We demonstrate some observations concerning the duration of pain after the injection and our indications for general anesthesia in ophthalmic surgery.

[Effect of diclofenac and flurbiprofen on the course of inflammation after cataract extraction]

In a prospective, randomized, double-blind study the effect of different anti-inflammatories (diclofenac 0.1%, flurbiprofen 0.03%) versus placebo on the intra- and postoperative inflammation in 65 eyes was examined. Prednisolone acetate 0.5% eye drops were the basic therapy in all three groups. As criteria served the difference between pre- and postoperative flare and cell concentration in the anterior chamber, measured using the laser flare cell meter, the clinical course, and the level of the inflammatory mediator 6-oxo-PGF1 alpha (prostacyclin) in the aqueous humor after intraoperative paracentesis, determined by means of enzyme-linked immunosorbent assay. The level of prostacyclin was not influenced in any of the three groups. The numbers of cells decreased continuously, but without marked differences among the groups. On the basis of the concentration of protein measured in the aqueous humor and the clinical course, diclofenac 0.1% proved to be a more potent additive anti-inflammatory therapy than flurbiprofen 0.03% immediately after the surgical procedure (P = 0.039 at 1 day after operation), but the final results (4 weeks after operation) revealed no detectable difference. By application of placebo, an obvious higher concentration of protein was measured during all the observations (P = 0.0002). Therefore in the case of cataract extraction the local steroidal therapy should be combined with nonsteroidal anti-inflammatory drugs (cyclooxygenase inhibitors).