The nicotine inhaler: clinical pharmacokinetics and comparison with other nicotine treatments.

Nicotine inhaled in smoke is the most rapid form of delivery of the drug. With smoking, arterial boli and high venous blood nicotine concentrations are produced within seconds and minutes, respectively. The potency of nicotine as the primary reinforcement in tobacco addiction is attributed to this rapid rate of delivery. By design, nicotine treatments reduce the rate and extent of drug delivery for weaning from nicotine during smoking cessation. Theoretically, they prevent relapse by reducing withdrawal and craving associated with the abrupt cessation of cigarettes. The nicotine inhaler treats the complexity of smoking through weaning both from the drug and from the sensory/ritual components associated with smoking. The inhaler is 'puffed' but not lit and there is considerable 'puffing' required to achieve slower rising and lower nicotine concentrations. These factors allow it to be used as a nicotine reduction treatment. One inhaler contains 10 mg of nicotine (and 1 mg of menthol) of which 4 mg of nicotine can be extracted and 2mg are systemically available. Shallow or deep 'puffing' results in similar nicotine absorption. Nicotine is delivered mainly to the oral cavity, throat and upper respiratory tract with a minor fraction reaching the lungs. This was confirmed with positron emission tomography and by assessment of arterial concentrations. A single inhaler can be used for one 20-minute period of continuous puffing or periodic use of up to 400 puffs per inhaler. With controlled puffing in laboratory testing, venous plasma nicotine concentrations from a single inhaler puffed 80 times over 20 minutes averaged 8.1 microg/L at 30 minutes. Lower concentrations of 6.4 to 6.9 microg/L have been reported for self-administration under clinical conditions. The time to peak plasma concentrations varies but is always significantly longer than with cigarette delivery. Estimates of nicotine intake from cotinine concentrations were higher than expected (60 to 70% of baseline smoking concentrations). This elevation may be due to the swallowing of nicotine and subsequent first-pass biotransformation to cotinine. In general, venous blood nicotine concentrations are considerably lower than with smoking and are within the range observed for other nicotine reduction therapies. Efficacy trials show consistent superiority of the inhaler over placebo. Despite the 'cigarette-like' appearance of the inhaler and the associated sensory/ritual elements, little treatment dependence or abuse has been reported. This is attributed to the slow rise time and low nicotine blood concentrations. The inhaler is a valuable addition to treatment of tobacco dependence and can be used alone or with other treatments.

Pharmacokinetic investigation of a nicotine sublingual tablet.

OBJECTIVE: To evaluate the pharmacokinetics of a new 2-mg nicotine sublingual tablet under varying conditions of use. METHODS: The pharmacokinetics of the 2-mg nicotine sublingual tablet were investigated in four separate studies involving healthy adult volunteer smokers: (1) a multiple-dose comparison with 2-mg nicotine chewing gum (n=24; 13 males, 11 females), (2) a dose-proportionality study comparing single doses of 2, 4 and 6 mg (n=21, 10 males, 11 females), (3) an evaluation of the effect of incorrect tablet use, i.e. chewing the tablet followed by either immediate or delayed swallowing (n = 19, 10 males, 9 females), and (4) the effect of oral and gastric pH on nicotine absorption from the tablet (n=20; 11 males, 9 females). Study parameters were maximal plasma concentration (Cmax), time to Cmax (tmax), and area under the plasma concentration-time curve (AUC). RESULTS: The plasma nicotine profiles were similar following repeated administration of the sublingual tablet and the 2-mg nicotine chewing gum (mean Cmax 13.2 versus 14.4 ng/ml, median tmax 20 versus 20 min, mean AUC11-12 12.4 versus 13.5 ng/ml per hour) with no statistically significant difference between the two treatments. The pharmacokinetics of the 4- and 6-mg doses were non-linear compared to the 2-mg dose, probably as a result of more of the dose being swallowed and undergoing first-pass metabolism in the liver. The mean Cmax for the 2-, 4- and 6-mg dose was 3.8 +/- 1.0, 6.8 +/- 2. 1, and 9.0 +/- 3.3 ng/ml, respectively, and in terms of dose proportionality the relative bioavailability of the 4- and 6-mg dose was 0.82 and 0.71, respectively. Incorrect tablet use, i.e. chewing the tablet and immediate swallowing decreased nicotine bioavailability both in terms of rate and extent. Mean Cmax was 12.1 ng/ml (correct use), 10.3 ng/ml (chewing and immediate swallowing), and 12.1 ng/ml (chewing and delayed swallowing). Corresponding mean values for AUC9-10 were 11.6, 9.6 and 11.2 ng/ml per hour. There were no significant differences between 'alkaline mouth' versus control, 'acidic mouth' versus control or 'alkaline stomach' versus control, but the rate of nicotine absorption was increased at alkaline compared to acidic oral pH (mean Cmax 6.1 versus 4.9 ng/l ml, P = 0.003; median tmax 60 versus 90 min, P= 0.0002). CONCLUSION: The pharmacokinetic profile of the nicotine 2-mg tablet was similar to that of the 2-mg nicotine chewing gum. Absorption of nicotine from the tablet was nonlinear at higher doses (two or three tablets). Chewing the tablet and keeping the remains in the mouth or concurrent use of acidic beverages or antacids are equivalent to recommended sublingual use during normal oral pH conditions.

Pharmacokinetics of nicotine in healthy elderly people.

BACKGROUND: Mortality hazards of smoking extend well into later life; this suggests that smoking cessation will continue to improve life expectancy in older people. The pharmacology and pharmacokinetics of nicotine have not been studied in elderly subjects. Drug disposition and pharmacodynamic responsiveness to nicotine may change with age, and conclusions founded on data from studies of younger populations may not apply to elderly populations. Our aim was to assess the pharmacokinetics of nicotine in healthy elderly subjects compared with healthy adults. METHODS: Twenty healthy elderly subjects (age, 65-76 years) and 20 healthy adult subjects (age, 22-43 years) were given an intravenous infusion of 0.028 mg/kg of nicotine over 10 minutes. Nicotine and cotinine concentrations were measured in plasma and urine. Heart rate and blood pressure were monitored. RESULTS: For most adult and elderly subjects nicotine distributed according to a two-compartment system. Even though there was a large interindividual variation within and overlap between groups, nicotine total clearance (-23%), nonrenal clearance (-21%), renal clearance (-49%), volume of central compartment (-37%), volume of distribution at steady state (-17%), and cotinine renal clearance (-18%) were statistically significantly decreased in elderly subjects compared with adults. Maximal heart rate response to nicotine was decreased in the elderly subjects (-29%). CONCLUSION: Even though statistically significant differences were observed, the disposition of nicotine does not seem to be changed to a clinically important extent in elderly subjects compared with younger adults.

Reduction of tobacco withdrawal symptoms with a sublingual nicotine tablet: a placebo controlled study.

Many smokers are unable to use gum as a cessation aid due to fillings, bridgework and dyspepsia or they reject it for esthetic reasons. The nicotine sublingual tablet is a new alternative to the nicotine polacrilex chewing gum that does not necessitate chewing. Twenty subjects used 2-mg sublingual nicotine tablets and placebo in a double-blind randomized crossover study of 2-day smoke-free periods. Craving and other withdrawal symptoms were rated on 100-mm visual analog scales (VAS) nine times over each 2-day period. Plasma nicotine concentrations in the afternoon of each study day were determined. A blood sample was also taken in the afternoon of a 2-day period with normal smoking. The mean number of nicotine tablets was 10 and seven on days 1 and 2, respectively. The corresponding number for placebo tablets was six and five. No subject used less than five tablets on any study day. The degree of nicotine substitution, defined as the quotient between the plasma levels achieved with the sublingual tablet and smoking, was 43, 30 and 23% for smokers with FTQ < or = 6, FTQ = 7 and FTQ > or = 8 (Fagerström Tolerance Questionnaire), respectively. Active treatment was significantly superior in decreasing craving and other withdrawal symptom scores compared to placebo treatment. Mean total scores were reduced by approximately 50%. Adverse events were mainly symptoms of local irritation such as a burning sensation in the throat or under the tongue, a lump in the throat and heartburn. These results demonstrate partial relief of the tobacco withdrawal syndrome with use of the sublingual tablet similar to that achieved from other forms of nicotine replacement.

Pharmacokinetics of nicotine in kidney failure.

BACKGROUND: Smoking is an important risk factor for cardiovascular and cerebrovascular complications in patients with chronic kidney failure. Very high plasma nicotine concentrations have been reported in patients with severe kidney failure, indicating that the disposition of nicotine in these patients may be different. The purpose of this study was to assess the pharmacokinetics of intravenously administered nicotine in healthy subjects and in patients with kidney failure. METHODS: Nine healthy subjects (glomerular filtration rate [GFR], 84 to 143 mL/min/1.73 m2), four patients with mild kidney failure (GFR, 63 to 73 mL/min/1.73 m2), five patients with moderate kidney failure (GFR, 18 to 36 mL/min/1.73 m2), and six patients with severe kidney failure (GFR, 1 to 10 mL/min/1.73 m2) were recruited. Three patients were treated with continuous ambulatory peritoneal dialysis. An intravenous infusion of nicotine (0.028 mg/kg) was given for 10 minutes. Nicotine and cotinine concentrations were measured in plasma, urine, and peritoneal dialysate from 0 to 24 hours after start of infusion RESULTS: There were significant correlations between GFR and total clearance, nonrenal and renal clearance of nicotine, area under the plasma concentration-time curve extrapolated to infinity, terminal elimination half-life, and mean residence time. Nonrenal clearance was 1303 mL/min and 661 mL/min in healthy subjects and patients with severe kidney failure, respectively. Only 1% to 2% of the nicotine dose was excreted unchanged in a 24-hour collection of peritoneal dialysate. The elimination of cotinine was also decreased in patients with kidney failure. CONCLUSION: Progressive kidney failure is associated with a gradual decrease of renal and nonrenal elimination of nicotine.

Acute effects of nicotine infusion on platelets in nicotine users with normal and impaired renal function.

The role of platelets in cardiovascular disease associated with smoking is becoming more established, but the effects of nicotine on platelets are unclear. Nicotine therapy is used for smoking cessation in both health and disease. Consequently, the effects of nicotine on platelets are of particular significance in disorders such as renal disease, which is associated with defective platelet function, increased cardiovascular morbidity, and altered nicotine metabolism. Thus, the aim of the present study was to investigate the acute effects of nicotine infusion (NI) on platelets in seven healthy subjects (HS) and seven patients with renal failure (RF). All subjects were nicotine users and had refrained from using nicotine for 36 h before NI. Blood was collected before, immediately after, and 2 h after NI. The plasma concentrations of nicotine and its main metabolite cotinine were determined by gas chromatography. Platelet responsiveness was assessed by aggregometry and flow cytometry in whole blood (P-selectin surface expression, fibrinogen- and von Willebrand factor-binding), P-selectin expression in isolated platelets, and immunoassays of platelet release (beta-thromboglobulin, platelet factor 4, and soluble P-selectin) and nitric oxide (NO) products. The plasma levels of cotinine, but not nicotine, were significantly higher in RF compared to HS at all time points. In both groups, collagen-induced platelet aggregation was restrained immediately after NI, when the plasma concentration of nicotine was maximal, and was restored after 2 h. Two hours after NI, activation-dependent P-selectin surface expression in isolated platelets increased in both groups. This increased platelet responsiveness occurred simultaneously with a significant increase of plasma cotinine and a decrease of NO products. Thus, the present study suggests that nicotine, directly or through some secondary mechanism or metabolite, only slightly potentiates some of the platelet responses. Renal failure appears not to influence the effects of nicotine on platelets.

Site of nicotine absorption from a vapour inhaler--comparison with cigarette smoking.

OBJECTIVE: The aim of the study was to assess the site of nicotine absorption during and after use of a nicotine-vapour inhaler compared with that after cigarette smoking. METHODS: Using a catheterisation technique, the nicotine plasma concentration-time profiles in arterial and jugular venous blood after using a nicotine inhaler were compared with those achieved after cigarette smoking a in seven healthy habitual smokers. RESULTS: After use of the inhaler, arterial nicotine concentrations rose slowly to a maximum level of 5. 9 +/- 1.5 ng/ml at a mean time to reach peak concentration (t(max)) of 9.0 +/- 1.1 min, whereas jugular venous nicotine levels peaked at 25.4 +/- 5.4 ng/ml at 6.7 +/- 0.3 min. The concentration-time curves indicate that the absorption occurs mainly via the mucosa of the oral cavity and the pharynx, and that there is minimal absorption via the lungs. In contrast, after smoking a cigarette, arterial nicotine plasma concentrations rose quickly to a maximum level of 49. 2 +/- 9.7 ng/ml after 4.0 +/- 0.6 min, while the maximum concentration of nicotine in the jugular vein was 22.4 +/- 3.9 ng/ml after 6.4 +/- 0.4 min, indicating primarily pulmonary absorption of nicotine. CONCLUSION: Nicotine absorption after use of the vapour inhaler occurs primarily via the mucosa of the oral cavity; the absorption occurs slowly and the arterial nicotine concentration spike, typical of cigarette smoking, is avoided. Thus, the likelihood for abuse of the nicotine inhaler is probably small.

Electroencephalographic effects of intravenous nicotine--a dose-response study.

RATIONALE: It has often been demonstrated that both tobacco abstinence and nicotine have effects on the EEG power spectrum and components of the event-related potentials. In contrast, few attempts have been made to establish the dose-response relationship between nicotine and EEG parameters. OBJECTIVES: The aim of this study was to investigate the dose-response relationship for EEG and auditory oddball P300 parameters over a wide range of intravenously infused nicotine doses. METHOD: Fourteen regular smokers who had abstained from nicotine for at least 12 h were given intravenous infusions of 0, 3.5, 7, 14 and 28 micrograms/kg nicotine over 10 min in a single-blind randomised cross-over design. Parallel recordings of spontaneous EEG, auditory P300 and heart rate, as well as venous blood sampling were made before, during and after nicotine administration. RESULTS: Linear dose-related decreases of delta and theta power were found, along with increases in alpha2 power and alpha peak frequency. Alpha1, beta and P300 parameters were unaffected. CONCLUSION: Our results are consistent with nicotine-dependent changes in EEG measures indicative of arousal.

Temperature dependency of the release and bioavailability of nicotine from a nicotine vapour inhaler; in vitro/in vivo correlation.

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 degrees, 30 degrees and 40 degrees C. In the in vitro experiment, 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 degrees C, 22 degrees C, 29 degrees C and 40 degrees C, respectively. The maximum dose released at the highest temperature (40 degrees C) and the largest air volume investigated (20 l) was approximately 7.5 mg. RESULTS: In vivo peak plasma levels obtained at 30 degrees and 40 degrees C were 29.7 and 34.0 ng.ml-1, compared with 22.5 ng.ml-1 at ambient room temperature (20 degrees C). At 20 degrees C, the area under the plasma concentration-time curve (AUC) of the last dosing interval was 20.5 ng.ml-1.h. At 30 degrees C and 40 degrees 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 degrees C and by 48% at 40 degrees C compared with the AUC at 20 degrees C. These increases should be compared to the in vitro results, showing a mean increase of 59% and 122% respectively, at 30 degrees and 40 degrees 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 degrees 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.

Aiding reduction of smoking with nicotine replacement medications: hope for the recalcitrant smoker?

OBJECTIVE: To assess the effect of the various nicotine replacement therapies (NRT) on smoking reduction. DESIGN: During an initial sampling week, the subjects familiarised themselves with nicotine gum, patch, nasal spray, vaporiser (vapour inhaler) and sublingual tablet. A crossover design was used during the next four study weeks; during two of these weeks the subjects could select one nicotine replacement product of their choice to use, whereas during the other two they were randomly assigned a product to use. SUBJECTS: 143 men and women smoking an average of 22.6 (SD 7.0) cigarettes per day and exhibiting a Fagerström Tolerance Questionnaire (FTQ) score of 7.0 (SD 1.9). INTERVENTIONS: Subjects were asked to use as much NRT as they wished, yet to smoke enough to feel comfortable. MAIN OUTCOME MEASURES: Self-reported cigarette consumption, exhaled carbon monoxide (CO), withdrawal symptom score, cotinine plasma levels and motivation to quit were monitored over a period of five weeks. RESULTS: Self-reported smoking declined steadily over the five weeks, from 22.6 (SD 7.0) to 10.4 (SD 1.0) (P<0.001) cigarettes daily (54% decrease), with the biggest drop (37%) during the first product-sampling week. Smoking reduction was greater on average during the weeks when the subjects could choose their nicotine product than when products were assigned. CO readings decreased from 22.7 (SD 8.5) to 14.8 (SD 8.4) ppm (P<0.001) confirming a reduction in smoking (35% decrease), although cotinine levels remained steady, suggesting that subjects were titrating nicotine to their original levels. Withdrawal scores decreased over time (32% decrease, P<0.001), showing that there was no discomfort associated with the smoking reduction, and motivation to quit was enhanced by the treatment in most subjects (93%). CONCLUSIONS: NRT for aiding smoking reduction appeared to be safe, was associated with a clinically significant reduction in smoke exposure over a five-week follow up, and increased motivation to stop smoking. A smoking reduction procedure may help the very recalcitrant smoker gain confidence and increase the control over his/her smoking behaviour. More controlled research is needed to follow up these promising results.

Exposure to high ambient temperature increases absorption and plasma concentrations of transdermal nicotine.

Absorption and plasma concentrations of transdermally delivered drugs may be increased during heat exposure. We studied the effects of short-term heat exposure in a sauna bath on the pharmacokinetics of transdermal nicotine, 25 mg/16 hr, in 12 healthy smokers in an open, randomized crossover study that consisted of a control session and a sauna bathing session. In the sauna session the subjects stayed seated in a sauna bath (mean temperature 82 degrees C (180 degrees F); mean relative humidity 28%) for three 10-minute periods separated by two 5-minute breaks. Sauna bathing significantly (p < 0.01 versus control) increased peak plasma concentration, area under the plasma concentration-time curve from 0 to 1 hour, the amount of nicotine absorbed, and the mean plasma nicotine concentrations during heat exposure. No significant difference in nicotine area under the plasma concentration-time curve from 0 to 3 hours was observed. In addition, the combined effects of transdermal nicotine and sauna bathing on hemodynamics, some psychomotor skills, and subjective symptoms were evaluated. We concluded that absorption and plasma concentrations of transdermally delivered nicotine may be increased during exposure to high ambient temperature, probably because of enhanced skin blood flow. However, no adverse symptoms were recorded.

Clinical pharmacokinetics of nasal nicotine delivery. A review and comparison to other nicotine systems.

Rapid drug delivery (arterial "boli') and high drug concentrations occur with nicotine inhaled in smoke. These are believed to be key elements in producing addiction to cigarettes. Preparations which reduce the rate of delivery and/or concentration of nicotine have been introduced as treatments for smoking cessation. These nicotine medications work by relieving withdrawal and preventing relapse associated with abrupt cessation of smoking. The pharmacokinetics of each system are expected to affect efficacy and treatment dependence. Nasal administration systems have been developed to more closely approximate cigarette delivery for improved efficacy in clinical application and for more control in systematic testing of nicotine. With laboratory tested nasal application systems (clinical drug and experimental devices), venous plasma concentrations after a single dose range between 5 and 12 micrograms/L. Higher steady-state blood nicotine concentrations (16 to 29 micrograms/L) have been reported for ad libitum clinical self-administration with a nicotine nasal spray. Time to peak plasma concentration (tmax) with nasal administration is around 11 to 13 minutes for 1 mg doses. This rise time is slower than for cigarette delivery but faster than the other nicotine treatments. Venous plasma concentrations are considerably lower than tobacco product concentrations and fall within the range of the lower dose nicotine treatments (e.g. 2 mg gum vs 4 mg gum). The profile of nasal nicotine administration was designed for certain subsets of smokers. Efficacy trials show consistent superiority of nasal administration over placebo although the comparative efficacy among nicotine treatments remains to be determined. The more rapid onset and user control of nasal nicotine may impose a higher risk for treatment dependence compared with a slower, passive system such as the patch. It may not produce more dependence than other faster-acting treatment systems (e.g. nicotine gum).

Dose released and absolute bioavailability of nicotine from a nicotine vapor inhaler.

In an open, randomized, three-way crossover study, 14 healthy smokers used one type of nicotine vapor inhaler intensely for 20 minutes every hour for 11 hours (12 administrations). Two different inhalation techniques were applied, shallow frequent sucking (buccal mode) and deep inhalations (pulmonary mode). The determination of nicotine was performed by capillary gas chromatography after single-step liquid-liquid extraction of the plasma sample. Nicotine was detected by means of a nitrogen-sensitive detector, giving high selectivity and sensitivity. The mean (+/- SD) nicotine dose released from each nicotine vapor inhaler unit was estimated at 4.00 +/- 0.60 mg (buccal mode) and 3.87 +/- 0.75 mg (pulmonary mode), inhaled with approximately 15 L of air. Mean (+/- SD) peak plasma level of the last dosing interval was 32.0 +/- 8.7 ng/ml and 34.2 +/- 8.9 ng/ml for the buccal and the pulmonary technique, respectively, achieved after 0.33 and 0.50 (median) hour, respectively. The mean (95% confidence interval [CI]) absolute bioavailability of nicotine was 51 (95% CI, 40 to 65) and 56 (95% CI, 47 to 67) when the buccal and pulmonary techniques were used, respectively. A significant correlation was found between systemically available dose and average steady-state nicotine plasma concentration. Based on the achievement of similar nicotine plasma levels, it may be concluded that the two modes of inhalation appear to be clinically equivalent.

Transdermally administered nicotine accumulates in gastric juice.

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. CONCLUSION: 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.

Regional deposition of inhaled 11C-nicotine vapor in the human airway as visualized by positron emission tomography.

The deposition of 11C-nicotine in the respiratory tract from a nicotine vapor inhaler was studied by means of positron emission tomography (PET) in an intrasubject comparison of six healthy smokers using two modes of inhalation: one with shallow, frequent inhalations ("buccal mode") and one with deep inhalations ("pulmonary mode"). An average of 15% of the radioactivity was released from the vapor inhaler after 5 minutes of inhalation. Approximately 45% of the dose released was found in the oral cavity. A significant amount of radioactivity, 10%, was observed in the esophagus, suggesting transfer of a major fraction of the dose to the stomach. Only a minor fraction, 5%, was found in the lungs, followed by 2% in the bronchi and 1% in the trachea. The deposition in the oral cavity closely followed a linear pattern during the 5 minutes of inhalation and was followed by a rapid elimination from the oral cavity, with an average half-life of 18 minutes. Only 8% of the dose released remained in the oral cavity 45 minutes after the end of inhalation. On the other hand, the dose fraction of about 14% distributed into the body tissue compartment at the end of inhalation had risen to 60% at that late time point. No statistically or clinically important differences were observed between the buccal and the pulmonary mode of inhalation in either deposition pattern or elimination rates.

Effect of nicotine vapour inhalation on the relief of tobacco withdrawal symptoms.

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 end-point is discussed.

Relative bioavailability of nicotine from a nasal spray in infectious rhinitis and after use of a topical decongestant.

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.

Effectiveness of nicotine patch and nicotine gum as individual versus combined treatments for tobacco withdrawal symptoms.

Nicotine gum and transdermal nicotine have been shown to relieve withdrawal and double success rates over placebo in trials of smoking cessation. This study tested whether combining the two methods would relieve withdrawal more effectively compared to either treatment alone. Twenty-eight smokers served as their own controls in each of four conditions: active gum + active patch (double active), active gum + placebo patch (gum only active), placebo gum + active patch (patch active) and placebo gum + placebo patch (double placebo). This "double placebo" design controls sensory, psychological and ritual variables associated with each drug form. Withdrawal symptoms were rated four times daily for 3 days in each condition. Total baseline (smoking) withdrawal scores using visual analogue scales (VAS) averaged 101.1. During cessation, total withdrawal increased to 187.0 for the double placebo condition, 142.2 for the active gum/placebo patch treatment and 128.3 for the active patch/placebo gum treatment. The double active condition equalled smoking with score 99.2. All pairwise comparisons were significant (P < 0.001) except between the two single active conditions and between smoking versus the double active condition. Significant time-of-day effects by treatment on withdrawal were observed for the double placebo condition (P < 0.05) with less withdrawal in the morning. The findings suggest: 1) combining nicotine gum with transdermal nicotine may be superior to either treatment alone, 2) more symptoms may be nicotine specific (relieved by replacement) than previously thought.

No effect of roxithromycin on pharmacokinetic or pharmacodynamic properties of warfarin and its enantiomers.

The macrolide antibiotics are metabolized by cytochrome P-450 enzymes in the liver and interactions with similarly metabolized compounds have been described. Simultaneous treatment with erythromycin and warfarin is known to decrease warfarin clearance and prolong prothrombin time. Roxithromycin (RU 28965), a new erythromycin derivative with improved pharmacokinetic properties, might then, because of structure similarity, be expected to interact with warfarin. In 21 healthy volunteers, the effect of orally administered roxithromycin (150 mg b.i.d.) on warfarin steady-state kinetics, and the effects of warfarin on roxithromycin kinetics, were investigated in a double-blind, randomized study versus placebo. Since the warfarin enantiomers, R- and S-warfarin have both different potency and different metabolism, the ratio between the enantiomers with and without roxithromycin, was also determined. In this study, mean AUC for warfarin increased slightly from day 14 of warfarin treatment to day 28, but no difference was found between the roxithromycin group and the placebo group, and no change appeared in the ratio between the warfarin enantiomers. A moderate increase in dosage was needed to maintain hypocoagulability during warfarin medication, but there was no difference between the roxithromycin group and the placebo groups, respectively. In addition, roxithromycin kinetics appeared to be unaffected by warfarin treatment.