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  • 1
    Electronic Resource
    Electronic Resource
    Temperature dependency of the release and bioavailability of nicotine from a nicotine vapour inhaler; in vitro/ in vivo correlation (1997)
    Springer
    European journal of clinical pharmacology 52 (1997), S. 495-500 
    Details
    ISSN: 1432-1041
    Keywords: Key words Nicotine ; vapour inhaler ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: To investigate the temperature dependency of the dose released and the plasma levels of nicotine from a vapour inhaler. Methods: In an open, randomised, three-way cross-over pharmacokinetic study 18 healthy subjects inhaled nicotine for 20 min (80 inhalations) every hour for 10 h (11 administrations) at three different environmental temperatures: 20°, 30° and 40 °C. In the in vitroexperiment, 5, 10, 15 and 20 l air were forced through the inhaler. With a 15 l air volume, the average amount of nicotine released was 1.44, 3.49, 4.80 and 6.99 mg at 10 °C, 22 °C, 29 °C and 40 °C, respectively. The maximum dose released at the highest temperature (40 °C) and the largest air volume investigated (20 l) was approximately 7.5 mg. Results: In vivo peak plasma levels obtained at 30° and 40 °C were 29.7 and 34.0 ng · ml−1, compared with 22.5 ng · ml−1 at ambient room temperature (20 °C). At 20 °C, the area under the plasma concentration–time curve (AUC) of the last dosing interval was 20.5 ng · ml−1 · h. At 30 °C and 40 °C, the AUCs were 26.5 and 30.3 ng · ml−1 · h, respectively. The results thus showed a mean increase of the in vivo AUC by 29% at 30 °C and by 48% at 40 °C compared with the AUC at 20 °C. These increases should be compared to the in vitro results, showing a mean increase of 59% and 122%, respectively, at 30° and 40 °C. The in vitro results also showed that a relatively larger fraction of the dose was released into the first 5 l of air at the higher temperatures, at 40 °C, about 50% of the total amount released into 20 l. Conclusion: It was concluded that the in vitro/in vivo discrepancy was most probably due to increased aversive effects at elevated temperatures, causing the subjects to inhale smaller puff volumes. Further, the inhaler would not produce nicotine plasma levels exceeding those achieved following cigarette smoking, even in a hot climate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050324
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of enprofylline, a xanthine lacking adenosine receptor antagonism, in patients with chronic obstructive lung disease (1982)
    Springer
    European journal of clinical pharmacology 22 (1982), S. 395-402 
    Details
    ISSN: 1432-1041
    Keywords: enprofylline ; theophylline ; obstructive lung disease ; adenosine ; antagonism ; bronchodilatation ; plasma levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Enprofylline, a xanthine-derivative shown experimentally to lack universal adenosine receptor antagonism, has been examined in patients with partly reversible, chronic, obstructive lung disease. Significant bronchodilation was produced by enprofylline 2 mg/kg, giving a peak plasma concentration of 3.0±0.6 µg/ml (mean ± SD). A dose of 2+4 mg/kg dilated the bronchi at least to the same extent as theophylline 9.2±0.9 mg/kg (plasma level 18.5±4.7 µg/ml). Neither at the low nor at the high dosage (2+4 mg/kg), giving plasma concentrations of 8.5±1.4 µg/ml, did enprofylline produce theophylline-like CNS effects, such as restlessness and tremor, but it did exhibit some of the innocuous side effects expected with xanthine derivatives, such as epigastric discomfort and headache. The comparison with theophylline was limited because different dosage forms had to be used (solution and tablets), which for example, resulted in different absorption rates. Nevertheless, the present findings indicate enprofylline to be a potent bronchodilator in patients with obstructive lung disease, suggesting that adenosine-receptor antagonism is not involved in the bronchodilator effects of xanthines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542541
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  • 3
    Electronic Resource
    Electronic Resource
    Additive bronchodilator effects of terbutaline and enprofylline in asthma (1987)
    Springer
    European journal of clinical pharmacology 32 (1987), S. 23-26 
    Details
    ISSN: 1432-1041
    Keywords: asthma ; enprofylline ; bronchodilatation ; combination treatment ; terbutaline ; plasma concentrations ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Enprofylline is a novel xanthine derivative with negligible adenosine antagonizing ability. It is eliminated almost exclusively by renal clearance with a half-life of about 2 h. Three i.v. infusions of enprofylline (1 mg/kg body weight over 10 min) were given at hourly intervals to 16 patients with stable, reversible airway obstruction. The patients were pretreated at random with i.v. terbutaline (4 µg/kg body weight) or placebo according to a double blind cross-over design. Lung function and drug concentrations in plasma were followed. Enprofylline produced significant and concentration-dependent bronchodilatation between plasma levels of 1.24 and 3.22 mg/l. The improvement in ventilatory function was significantly enhanced by terbutaline pretreatment. At the highest plasma levels of enprofylline nausea and headache were found as subjective side effects. The results suggest that enprofylline and terbutaline might best be used in a low dose combination in the treatment of bronchial asthma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609953
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  • 4
    Electronic Resource
    Electronic Resource
    Absorption of enprofylline from the gastrointestinal tract in healthy subjects (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 329-333 
    Details
    ISSN: 1432-1041
    Keywords: enprofylline ; healthy subjects ; absorption ; pharmacokinetics ; oral- ; duodenal- ; colonic administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Enprofylline, a new potent bronchodilator xanthine drug, was given orally as an aqueous solution to 6 healthy subjects in single doses of 2, 4 and 6 mg/kg. The two lower doses produced plasma concentrations in the range 1–4 mg/l, i.e. in the assumed “therapeutic interval” according to previous animal studies. A high 24 h urine recovery of unchanged drug, with mean values for the three dose levels ranging from 85 to 91% of the given dose, indicated good absorption and little metabolism. The dose-corrected area under the plasma concentration-time curve rose with dose as the latter was increased from 2 to 6 mg/kg. This indicates that the elimination of enprofylline is capacity-limited at high doses. Double peaks in the plasma concentration-time curves at the higher dose levels suggested intermittent and delayed gastric emptying as a possible explanation. This hypothesis was confirmed by studies in 6 other healthy subjects, who received the drug solution by three different routes; by mouth, via a catheter in the duodenum, and rectally via a catheter in the colon. The corresponding time to peak values (mean±SEM) were 32.5±8.7, 13.3±2.5, and 157±23 min.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542170
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  • 5
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of enprofylline in healthy elderly subjects (1987)
    Springer
    European journal of clinical pharmacology 32 (1987), S. 67-70 
    Details
    ISSN: 1432-1041
    Keywords: enprofylline ; pharmacokinetics ; elderly ; renal excretion ; half-life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of enprofylline, a new potent antiasthmatic, has been studied in 20 healthy, elderly subjects, aged 65 to 81 years, and in 7 young adult controls, aged 23 to 37 years. The dose of 1 mg/kg body weight was given as an i.v. infusion. Plasma levels of enprofylline were followed for about 7 h and urine levels for 24 h. Both groups eliminated the major portion of the dose (about 83%) by renal excretion. As expected the mean creatinine clearance (92.5 ml·min−1· 1.73 m−2) was moderately decreased in the elderly subjects. The total clearance of enprofylline was 0.16 1·h−1·kg−1 and the renal clearance was 0.13 l·h−1·kg−1, which was significantly lower than that in the young controls (0.28 and 0.22 l·h−1·kg−1) respectively. Thus, the enprofylline clearance had fallen relatively more (about 40%) than the decrease in creatinine clearance (about 20%) with age. The half-life of enprofylline in old age was 2.5 h, which was significantly longer than in the younger adults (1.8 h). It is concluded that the pharmacokinetics of enprofylline was significantly influenced by advanced age, mainly due to reduced renal excretion. This reduction was more pronounced than anticipated from the age-dependent decline in creatinine clearance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609959
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  • 6
    Electronic Resource
    Electronic Resource
    Relative bioavailability of nicotine from a nasal spray in infectious rhinitis and after use of a topical decongestant (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 71-75 
    Details
    ISSN: 1432-1041
    Keywords: Nicotine ; Rhinitis ; pharmacokinetics ; nasal spray ; xylometazoline ; drug interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The relative bioavailability of nicotine from a nasal spray was assessed in 15 smokers suffering a common cold and rhinitis according to generally accepted criteria. The patients were given a single dose of 2 mg nicotine from the nasal spray with and without concurrent administration of a nasal vasoconstrictor decongestant, xylometazoline, in randomised order. Control session measurements were made in the disease-free state. Applying strict bioequivalence criteria, we found that common cold/rhinitis slightly reduced the bioavailability of nicotine, both in its rate and extent; the geometric mean of the ratio of Cmax, AUC and tmax were 0.81, 0.93 and 1.36, respectively. The nasal vasoconstrictor, xylometazoline, normalised the extent of the bioavailability of nicotine, but further prolonged the time for absorption to almost twice that measured in the disease-free state, increasing the tmax ratio to 1.72. The results suggest that a minor proportion of people stopping smoking with the help of a nicotine nasal spray may experience a minor reduction in the effect of the spray during common cold/rhinitis. However, the nicotine self-titration behaviour found with most smoking cessation products (except the nicotine patch) will automatically lead to an adjustment of the dosage to achieve the desired effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202176
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  • 7
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of enprofylline in patients with impaired renal function after a single intravenous dose (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 87-93 
    Details
    ISSN: 1432-1041
    Keywords: enprofylline ; pharmacokinetics ; renal elimination ; renal insufficiency ; healthy subjects ; creatinine clearance ; side effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Enprofylline, a new bronchodilating drug, was given i.v. at 1.0 mg/kg to 7 healthy subjects and to 14 patients with differing degrees of chronic renal insufficiency. Plasma and urine concentrations of unchanged drug were followed by HPLC. In the patients the plasma half-life was prolonged and the total and renal clearances were reduced in direct proportion to the degree of renal insufficiency as determined by creatinine clearance. The unbound fraction of enprofylline in plasma increased from 55% in the healthy subjects to 66% in the group of patients with the highest degree of renal impairment. The volume of distribution terms, Vβ and Vss, both tended to decrease with decreasing creatinine clearance. When the volume term calculations were based on the unbound drug level in plasma, this tendency was enhanced. Side-effects were noted in 4 subjects, and to some extent were related to the plasma level of the drug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00546714
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of probenecid on enprofylline kinetics in man (1986)
    Springer
    European journal of clinical pharmacology 30 (1986), S. 221-223 
    Details
    ISSN: 1432-1041
    Keywords: enprofylline ; probenecid ; pharmacokinetics ; renal elimination ; active secretion ; drug interaction ; healthy subjects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Enprofylline 1 mg/kg, a new potent antiasthmatic xanthine derivative, which is mainly eliminated by renal excretion, was given intravenously to 6 normal subjects with and without oral pretreatment with 1 g probenecid. The latter caused a drop in the average total body clearance of enprofylline from 21 to 9.8 l/h, and in the average renal clearance from 17 to 8.0 l/h. The average half-life increased from 1.8 to 3.0 h. The volumes of distribution, Vz and Vss, both fell by about 25%, indicating that probenecid had restricted the distribution of enprofylline in the body. The plasma protein binding of enprofylline was not altered by probenecid. The results confirm the opinion that active tubular secretion accounts for a large proportion of the total elimination of enprofylline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614308
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of nicotine vapour inhalation on the relief of tobacco withdrawal symptoms (1995)
    Springer
    European journal of clinical pharmacology 48 (1995), S. 235-240 
    Details
    ISSN: 1432-1041
    Keywords: Nicotine ; withdrawal symptoms ; craving ; inhalation ; plasma concentrations ; vapour inhaler ; smoking cessation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Fifteen subjects participated in a randomised, placebo-controlled cross-over study to assess the effect of a nicotine vapour inhaler on craving and other withdrawal symptoms during a two-day smoking-free period. Craving and withdrawal symptoms were rated nine times over the two-day period on 10 cm visual analogue scales. Plasma nicotine concentrations in the afternoon of each study day were determined. The results show that active treatment was significantly superior to placebo in decreasing craving and other withdrawal symptom scores. No difference was found between two inhalation techniques, one with shallow, frequent inhalations (buccal technique), and the other with deep inhalations (pulmonary technique). The average number of active nicotine vapour inhalers and placebo inhalers used during the two-day sessions was 12 and 11, respectively. Afternoon plasma nicotine levels of approximately 7 ng/ml were obtained with both inhalation techniques. A strong correlation was found between the afternoon plasma nicotine levels and craving, a high nicotine level being associated with a low craving score. The study has provided information about how to use the nicotine vapour inhaler that could have important implications if it were to be approved for the treatment of tobacco dependence. The use of withdrawal symptom reduction as a surrogate endpoint is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198304
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  • 10
    Electronic Resource
    Electronic Resource
    Transdermally administered nicotine accumulates in gastric juice (1996)
    Springer
    European journal of clinical pharmacology 51 (1996), S. 315-318 
    Details
    ISSN: 1432-1041
    Keywords: Key words Gastric juice; nicotine ; ion-trapping ; peptic ulcer disease ; smoking cessation ; transdermal patch ; saliva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Methods: Transdermal nicotine patches (Nicorette® 15 mg ⋅ 16 h–1) were administered to 7 healthy volunteers. Nicotine concentrations in gastric juice were monitored for 8 h via a naso-gastric tube and so was nicotine in saliva and plasma. Results: Nicotine accumulated in gastric juice, the average concentration being 60.6-times higher than in plasma. In saliva, too, the concentration was higher than in plasma, the average ratio being 10.5. These results strongly suggested ion-trapping of nicotine base in the acidic gastric juice and possibly also in the acinar cells, followed by active secretion. It is hypothesised that accumulation in saliva occurs via a similar mechanism. Pretreatment with omeprazole did not increase the pH to a sufficiently high degree to test the hypothesis that the accumulation of nicotine in gastric juice was pH dependent. Conclusions: Transdermal administration of nicotine produced a high intragastric concentration. The clinical consequence of this effect of long-term nicotine replacement therapy during smoking cessation is unclear.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050204
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