Steady-state pharmacokinetics and dose relationship of nicotine delivered from Nicoderm (Nicotine Transdermal System)

Attention-enhancing effects of propranolol and synergistic effects with nicotine

Nicotine increases the output of every major neurotransmitter. In previous studies designed to identify the secondary neurotransmitter systems mediating nicotine's attention-enhancing effects in a rat model, the β-adrenoceptor antagonist propranolol blocked these effects. The present study was designed to test whether this mechanism held true in humans, thus guiding development of novel nicotinic agonists for cognitive enhancement. Twenty-six nonsmokers completed a nicotine (7 mg/24 h transdermally) x propranolol (40 mg p.o., body weight-adjusted) interaction study. Over four test days, each participant received double-placebo, nicotine only, propranolol only, and nicotine plus propranolol in randomized sequence before cognitive testing. No drug effects were seen in a visuospatial attention task. In the Rapid Visual Information Processing Task, performed in two 15-min blocks, neither drug alone significantly affected hit rate, but both drugs combined acted synergistically to alleviate its decrement over time in the first block and displayed additive beneficial effects in the second. In a change detection task, propranolol enhanced accuracy and reduced reaction time independent of nicotine presence. Propranolol also enhanced subjective self-reports of vigor. Overall, the findings were contrary to those hypothesized. Propranolol displayed beneficial effects on cognition, especially on sustaining performance over time. β-adrenoceptor activation by nicotine-induced noradrenaline release appeared to limit performance-enhancing effects of nicotine, because they were unmasked by β-adrenoceptor antagonism. The results suggest that cognitive effects of changes in β-adrenoceptor tone are context-dependent; contrary to rodent paradigms, human cognitive paradigms require no physical orienting in space but prolonged periods of remaining stationary while sustaining predictable processing demands.

Nicotinic receptor modulation of the default mode network

RATIONALE

Previous neuroimaging studies of cognition involving nicotinic acetylcholine receptor (nAChR) agonist administration have repeatedly found enhanced task-induced deactivation of regions of the default mode network (DMN), a group of brain systems that is more active at rest and mediates task-independent thought processes. This effect may be related to pro-cognitive nAChR agonist effects OBJECTIVES: The present study sought to test whether nAChR modulation of the DMN is bi-directional, i.e., whether a nAChR antagonist would reduce task-induced deactivation.

METHODS

Eighteen healthy non-smokers underwent functional magnetic resonance imaging while performing a letter N-back task. Scans were performed after nicotine administration (7 mg/24 h, transdermally), after administration of the nAChR antagonist mecamylamine (7.5 mg, p.o.), and after double placebo, in counterbalanced sequence. Blood-oxygen-level-dependent (BOLD) signal was analyzed within ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (PCC) regions of interest-central hubs of the DMN in which consistent nAChR agonist-induced changes had previously been identified.

RESULTS

Nicotine enhanced hit rate in both the 0-back and 2-back condition, while mecamylamine slowed reaction time in the 2-back condition. Mecamylamine reduced task-induced deactivation of vmPFC and PCC. Nicotine had no significant effects on the BOLD signal.

CONCLUSIONS

The finding that nAChR tone reduction by mecamylamine weakened task-induced DMN deactivation indicates that a constant tone of nAChR activation helps regulate DMN activity in healthy individuals. This suggests that low nAChR tone may play a causal role in DMN dysregulation seen in conditions such as mild cognitive impairment or Alzheimer's disease.

Evidence for positive allosteric modulation of cognitive-enhancing effects of nicotine in healthy human subjects

RATIONALE

Cognitive benefits of nicotinic acetylcholine receptor (nAChR) agonists are well established but have generally been of small magnitude and uncertain clinical significance. A way of raising the effect size may be to facilitate agonist-induced responses by co-administering a nAChR positive allosteric modulator (PAM).

OBJECTIVE

The aim was to test whether galantamine, a PAM at several nAChR subtypes, can potentiate the cognitive-enhancing effects of nicotine.

METHODS

Twenty-six adult never-smokers were treated, in a double-blind counterbalanced sequence, with nicotine (7 mg/24 h, transdermally) and galantamine (4 mg, p.o.) combined, nicotine alone, galantamine alone, and double placebo. A low dose of galantamine was chosen to minimize acetylcholinesterase inhibition, which was verified in blood assays. In each condition, participants were tested with three cognitive tasks.

RESULTS

Nicotine significantly improved reaction time (RT) and signal detection in a visuospatial attention task and the Rapid Visual Information Processing Task. Galantamine did not modulate these effects. A trend toward RT reduction by galantamine correlated with acetylcholinesterase inhibition. In a change detection task, there were no effects of nicotine or galantamine alone on accuracy or RT. However, both drugs combined acted synergistically to reduce RT. This effect was not associated with acetylcholinesterase inhibition.

CONCLUSIONS

A pattern consistent with allosteric potentiation of nicotine effects by galantamine was observed on one of six performance measures. This may reflect specific nAChR subtype involvement, or additional pharmacological actions of galantamine may have overshadowed similar interactions on other measures. The finding suggests that allosteric potentiation of nAChR agonist-induced cognitive benefits is possible in principle.

Pharmacokinetic Evaluation of Two Nicotine Patches in Smokers

Smoking continues to be a major preventable cause of early mortality worldwide, and nicotine replacement therapy has been demonstrated to increase rates of abstinence among smokers attempting to quit. Nicotine transdermal systems (also known as nicotine patches) attach to the skin via an adhesive layer composed of a mixture of different‐molecular‐weight polyisobutylenes (PIBs) in a specific ratio. This randomized, single‐dose, 2‐treatment, crossover pharmacokinetic (PK) trial assessed the bioequivalence of nicotine patches including a replacement PIB adhesive (test) compared with the PIB adhesive historically used on marketed patches (reference). The test and reference patches were bioequivalent, as determined by the PK parameters of C_max and AUC_0–t. In addition, the parameters T_max and t_1/2 did not significantly differ between the 2 patches, supporting the bioequivalence finding from the primary analysis. The tolerability profiles of the patches containing the replacement and previously used PIB adhesives were similar; application‐site adverse events did not significantly differ between test and reference patches. Overall, these data establish the bioequivalence of the nicotine patch with the replacement PIB adhesive formulation and the previously utilized PIB adhesive formulation.

Effects of nicotine on response inhibition and interference control

Nicotine is a cholinergic agonist with known pro-cognitive effects in the domains of alerting and orienting attention. However, its effects on attentional top-down functions such as response inhibition and interference control are less well characterised. Here, we investigated the effects of 7 mg transdermal nicotine on performance on a battery of response inhibition and interference control tasks. A sample of N = 44 healthy adult non-smokers performed antisaccade, stop signal, Stroop, go/no-go, flanker, shape matching and Simon tasks, as well as the attentional network test (ANT) and a continuous performance task (CPT). Nicotine was administered in a within-subjects, double-blind, placebo-controlled design, with order of drug administration counterbalanced. Relative to placebo, nicotine led to significantly shorter reaction times on a prosaccade task and on CPT hits but did not significantly improve inhibitory or interference control performance on any task. Instead, nicotine had a negative influence in increasing the interference effect on the Simon task. Nicotine did not alter inter-individual associations between reaction times on congruent trials and error rates on incongruent trials on any task. Finally, there were effects involving order of drug administration, suggesting practice effects but also beneficial nicotine effects when the compound was administered first. Overall, our findings support previous studies showing positive effects of nicotine on basic attentional functions but do not provide direct evidence for an improvement of top-down cognitive control through acute administration of nicotine at this dose in healthy non-smokers.

Nicotine reduces distraction under low perceptual load

RATIONALE

Several studies provide evidence that nicotine alleviates the detrimental effects of distracting sensory stimuli. It is been suggested that nicotine may either act as a stimulus filter that prevents irrelevant stimuli entering awareness or by enhancing the attentional focus to relevant stimuli via a boost in processing capacity.

OBJECTIVES

To differentiate between these two accounts, we administered nicotine to healthy non-smokers and investigated distractor interference in a visual search task with low and high perceptual load to tax processing capacity.

METHODS

Thirty healthy non-smokers received either 7 mg transdermal nicotine or a matched placebo in a double blind within subject design 1 h prior to performing the visual search task with different fixation distractors.

RESULTS

Nicotine reduced interference of incongruent distractors, but only under low-load conditions, where distractor effects were large. No effects of nicotine were observed under high-load conditions. Highly distractible subjects showed the largest effects of nicotine.

CONCLUSIONS

The findings suggest that nicotine acts primarily as a stimulus filter that prevents irrelevant stimuli from entering awareness in situations of high distractor interference.

Acute nicotine differentially impacts anticipatory valence- and magnitude-related striatal activity

BACKGROUND

Dopaminergic activity plays a role in mediating the rewarding aspects of abused drugs, including nicotine. Nicotine modulates the reinforcing properties of other motivational stimuli, yet the mechanisms of this interaction are poorly understood. This study aimed to ascertain the impact of nicotine exposure on neuronal activity associated with reinforcing outcomes in dependent smokers.

METHODS

Smokers (n = 28) and control subjects (n = 28) underwent functional imaging during performance of a monetary incentive delay task. Using a randomized, counterbalanced design, smokers completed scanning after placement of a nicotine or placebo patch; nonsmokers were scanned twice without nicotine manipulation. In regions along dopaminergic pathway trajectories, we considered event-related activity for valence (reward/gain vs. punishment/loss), magnitude (small, medium, large), and outcome (successful vs. unsuccessful).

RESULTS

Both nicotine and placebo patch conditions were associated with reduced activity in regions supporting anticipatory valence, including ventral striatum. In contrast, relative to controls, acute nicotine increased activity in dorsal striatum for anticipated magnitude. Across conditions, anticipatory valence-related activity in the striatum was negatively associated with plasma nicotine concentration, whereas the number of cigarettes daily correlated negatively with loss anticipation activity in the medial prefrontal cortex only during abstinence.

CONCLUSIONS

These data suggest a partial dissociation in the state- and trait-specific effects of smoking and nicotine exposure on magnitude- and valence-dependent anticipatory activity within discrete reward processing brain regions. Such variability may help explain, in part, nicotine's impact on the reinforcing properties of nondrug stimuli and speak to the continued motivation to smoke and cessation difficulty.

Chronic exposure to nicotine is associated with reduced reward-related activity in the striatum but not the midbrain

BACKGROUND

The reinforcing effects of nicotine are mediated by brain regions that also support temporal difference error (TDE) processing; yet, the impact of nicotine on TDE is undetermined.

METHODS

Dependent smokers (n = 21) and matched control subjects (n = 21) were trained to associate a juice reward with a visual cue in a classical conditioning paradigm. Subjects subsequently underwent functional magnetic resonance imaging sessions in which they were exposed to trials where they either received juice as temporally predicted or where the juice was withheld (negative TDE) and later received unexpectedly (positive TDE). Subjects were scanned in two sessions that were identical, except that smokers had a transdermal nicotine (21 mg) or placebo patch placed before scanning. Analysis focused on regions along the trajectory of mesocorticolimbic and nigrostriatal dopaminergic pathways.

RESULTS

There was a reduction in TDE-related function in smokers in the striatum, which did not differ as a function of patch manipulation but was predicted by the duration (years) of smoking. Activation in midbrain regions was not impacted by group or drug condition.

CONCLUSIONS

These data suggest a differential effect of smoking status on the neural substrates of reward in distinct dopaminergic pathway regions, which may be partially attributable to chronic nicotine exposure. The failure of transdermal nicotine to alter reward-related functional processes, either within smokers or between smokers and control subjects, implies that acute nicotine patch administration is insufficient to modify reward processing, which has been linked to abstinence-induced anhedonia in smokers and may play a critical role in smoking relapse.

Effects of nicotine on electroencephalography and affect in adolescent females with major depressive disorder: a pilot study

BACKGROUND

Given that smoking is typically initiated during adolescence, and that this period in brain development seems to be uniquely sensitive to nicotine, depressed youth may be most susceptible to the neuromodulatory and mood-altering effects of nicotine. Electroencephalographic (EEG) studies suggest that individuals with major depressive disorder (MDD) exhibit left frontal lobe hypoactivation (indexed by increased EEG alpha), a region implicated in positive affect regulation, as well as right parietal hypoactivation. Smoking/nicotine abstinence has been associated with increased left frontal and right parietal alpha activity (reduced activation), which has been correlated with increased depression ratings; nicotine administration seems to normalize this depression-associated asymmetry.

OBJECTIVES

This pilot study investigated whether acute nicotine administration in adolescent female smokers with MDD would alter resting EEG activity and affect.

METHODS

Subjective mood ratings and EEG recordings were acquired before and 2 hours after administering a transdermal placebo or nicotine (21 mg) patch to 8 adolescent female smokers with MDD.

RESULTS

Nicotine induced a modest increase in alpha1 amplitude in the right hemisphere and simultaneously decreased left-favoring alpha1 amplitude asymmetry. It also attenuated left alpha1 and alpha2 amplitude in the central region. Consistent with nicotine's stimulatory action, nicotine decreased theta amplitude in the right parietal region. No accompanying mood alterations were found, although smoking withdrawal and craving as well as physical symptom scores were reduced with nicotine.

CONCLUSIONS

The results of this pilot study, the first to examine the electrocortical effects of nicotine in depressed adolescents, indicate that nicotine modulates EEG asymmetry measures, laying the stage for further research regarding the role of nicotine on affective neurocircuitry in this population.

Nicotine effects on immediate and delayed verbal memory after substance use detoxification

Decrements in verbal memory are commonly reported by detoxified treatment-seeking individuals. Although acute nicotine has been shown to improve attentional performance, its effects on verbal memory in substance abusers have not been addressed. Treatment-seeking alcohol-dependent (ALCs, n = 29; 14 male), illicit-stimulant-dependent (predominantly cocaine; STIMs, n = 25; 15 male), and alcohol- and illicit-stimulant-dependent (ALC/STIMs, n = 50; 35 male) participants with comorbid nicotine dependence were studied. Subjects had been abstinent from their drugs of choice for 41 (±18) days and were in short-term abstinence from tobacco (∼8-10 hours). Subjects received double-blind administration of either transdermal nicotine (high dose: 21/14 mg for men and women, respectively, or low dose: 7 mg) or placebo. The Logical Memory (LM) subtest from the Wechsler Memory Scale-Revised (WMS-R) was used to assess immediate and delayed verbal memory recall. Results indicated that STIMs receiving the high dose of nicotine recalled more words at immediate recall than STIMs who received placebo. Trend level differences were also noted at delayed recall between STIM nicotine and placebo doses. Nicotine failed to impact either recall in alcoholic subgroups. Although not the primary focus, results also revealed differences in the forgetting rates between the groups with the ALC/STIMs demonstrating the steepest forgetting slope. In summary, this study suggests that nicotine effects may be differentially experienced by substance-using subgroups; that nicotine may have a direct effect on memory; and that in considering neurocognitive processes (e.g., encoding vs. retrieval), underlying endpoint indicators (e.g., correct recall) may be critical in predicting outcomes.

Nicotine as a factor in stress responsiveness among detoxified alcoholics

AIMS

The effect of transdermal nicotine on stress reactivity was investigated in currently smoking, detoxified, substance-dependent individuals (65% alcohol dependent, n = 51; 31 male) following a psychosocial stressor.

METHODS

Using a randomized, double-blind, placebo-controlled design, subjects were assigned to receive either active transdermal nicotine (low or high dose) or placebo. Six hours following nicotine administration, subjects performed a laboratory psychosocial stressor consisting of two 4-min public-speaking sessions.

RESULTS

Consistent with prior reports, substance-dependent individuals displayed a blunted stress response. However, a review of the cortisol distribution data encouraged additional analyses. Notably, a significant minority of the substance-dependent individuals (33%) demonstrated elevated poststress cortisol levels. This group of responders was more likely to be alcohol dependent and to have received the high dose of nicotine [χ2(2) = 32, P < 0.0001], [χ2(2) = 18.66, P < 0.0001]. Differences in salivary cortisol responses between responders and nonresponders could not be accounted for by the length of sobriety, nicotine withdrawal levels, anxiety or depressive symptomatology at the time of the psychosocial stressor.

CONCLUSION

These results suggest that nicotine administration may support a normalization of the salivary cortisol response following psychosocial stress in subgroups of substance-dependent individuals, particularly those who are alcohol dependent. Given the association between blunted cortisol levels and relapse, and the complex actions of nicotine at central and peripheral sites, these findings support the systematic study of factors including nicotine, which may influence stress reactivity and the recovery process in alcohol-dependent individuals.

A novel validated procedure for the determination of nicotine, eight nicotine metabolites and two minor tobacco alkaloids in human plasma or urine by solid-phase extraction coupled with liquid chromatography-electrospray ionization-tandem mass spectrometry

A novel validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) procedure was developed and fully validated for the simultaneous determination of nicotine-N-beta-D-glucuronide, cotinine-N-oxide, trans-3-hydroxycotinine, norcotinine, trans-nicotine-1'-oxide, cotinine, nornicotine, nicotine, anatabine, anabasine and cotinine-N-beta-D-glucuronide in human plasma or urine. Target analytes and corresponding deuterated internal standards were extracted by solid-phase extraction and analyzed by LC-MS/MS with electrospray ionization (ESI) using multiple reaction monitoring (MRM) data acquisition. Calibration curves were linear over the selected concentration ranges for each analyte, with calculated coefficients of determination (R(2)) of greater than 0.99. The total extraction recovery (%) was concentration dependent and ranged between 52-88% in plasma and 51-118% in urine. The limits of quantification for all analytes in plasma and urine were 1.0 ng/mL and 2.5 ng/mL, respectively, with the exception of cotinine-N-beta-D-glucuronide, which was 50 ng/mL. Intra-day and inter-day imprecision were < or = 14% and < or = 17%, respectively. Matrix effect (%) was sufficiently minimized to < or = 19% for both matrices using the described sample preparation and extraction methods. The target analytes were stable in both matrices for at least 3 freeze-thaw cycles, 24 h at room temperature, 24 h in the refrigerator (4 degrees C) and 1 week in the freezer (-20 degrees C). Reconstituted plasma and urine extracts were stable for at least 72 h storage in the liquid chromatography autosampler at 4 degrees C. The plasma procedure has been successfully applied in the quantitative determination of selected analytes in samples collected from nicotine-abstinent human participants as part of a pharmacokinetic study investigating biomarkers of nicotine use in plasma following controlled low dose (7 mg) transdermal nicotine delivery. Nicotine, cotinine, trans-3-hydroxycotinine and trans-nicotine-1'-oxide were detected in the particular sample presented herein. The urine procedure has been used to facilitate the monitoring of unauthorized tobacco use by clinical study participants at the time of physical examination (before enrollment) and on the pharmacokinetic study day.

Death due to ingestion of nicotine-containing solution: case report and review of the literature

Nicotine, a lipid-soluble alkaloid obtained from the dried leaves of Nicotiana, is most frequently encountered in tobacco products for smoking, chewing or sniffing as well as in a limited number of pesticides. Though nicotine is one of the most toxic drugs of abuse, it has rarely led to fatalities. Sudden death can be caused by cardiovascular arrest, respiratory muscle paralysis and/or central respiratory failure. A 42-year-old man was found dead by his wife. He was lying on the floor, next to a box containing many empty bottles of beer and vodka. Some labeled chemical bottles found at the scene contained various substances, including nicotine and brucine. Gross examination of the organs at autopsy revealed no specific findings. The toxicological examination failed to disclose any lethal toxic agents other than a high concentration of nicotine and its primary metabolite cotinine in femoral venous blood (2.2 microg/mL). Blood alcohol was determined to be 2.1 g/L in femoral venous blood. Only a paucity of fatal cases of nicotine poisoning has been reported in the literature so far.

Comparison of Nicotine Pharmacokinetics in Healthy Japanese Male Smokers Following Application of the Transdermal Nicotine Patch and Cigarette Smoking

Transdermal nicotine patch (TNP) contains approximately 16.6 and 24.9 mg of nicotine per 20 and 30 cm2 (TNP-20 and TNP-30). The aims of the study are to investigate linearity of nicotine pharmacokinetics after single application of different strengths of TNP and to directly compare plasma nicotine concentrations with those during cigarette smoking. Twelve healthy Japanese male smokers were randomly allocated to 1 of 2 cohorts consisting of 6 subjects each. Cohort 1 subjects received 1 sheet of TNP-20 (TNP-20x1) in period 1, and 2 sheets of TNP-20 (TNP-20x2) in period 3. Cohort 2 subjects were received 1 sheet of TNP-30 (TNP-30x1) in period 2, and smoked a total of 12 cigarettes at 1 h intervals in period 4. Each TNP was applied to the upper arm for 16 h. After TNP-20x1 or TNP-20x2 treatment in cohort 1, the amount of nicotine delivered from TNP (Dose) was proportional to surface area of TNP. Cmax and AUC of nicotine increased with the surface area (Dose), and tmax, t(1/2), CL/F and percentage of dose excreted in urine were almost the same between both treatments. These suggest the linear pharmacokinetics of nicotine in proportion to the surface area and Dose following single application of TNP in identical subjects. In cohort 2, the plasma nicotine concentrations after TNP-30x1 treatment were approximately half those just before each smoking.

Effect of prolonged nicotine infusion on response of rat catecholamine biosynthetic enzymes to restraint and cold stress

There is a paradoxical relationship between nicotine and stress. To help elucidate their relationship on catecholamine biosynthesis, rats were infused with nicotine for 7-14 days before exposure to cold or restraint stress. Nicotine (5 mg/kg/day, 14 days) did not alter basal plasma corticosterone or its elevation with 24 h cold stress, but prevented corticosterone elevation following 2 h restraint stress. In adrenal medulla (AM), response of dopamine beta-hydroxylase (DBH), but not tyrosine hydroxylase (TH) mRNA, to both stressors was attenuated in nicotine-infused rats. In locus coeruleus (LC), restraint stress elevated TH and DBH mRNA in saline-, but not in nicotine-infused rats. Cold stress triggered a similar response of TH and DBH mRNAs in LC with and without nicotine infusion. With shorter nicotine infusion (8 mg/kg/day, 7 days), TH mRNA in AM was not induced by restraint stress on one (1x) or two (2x) consecutive days nor was DBH mRNA in AM or LC by 2x. The findings demonstrate that constant release of nicotine can modulate, or even prevent, some stress responses at the level of the HPA axis and gene expression of catecholamine biosynthetic enzymes in LC and AM.

Metabolism and biochemical effects of nicotine for primary care providers

Nicotine is a colorless and volatile liquid alkaloid naturally occurring in the leaves and stems of Nicotiana tabacum and Nicotiana rustica. Nicotine, the primary component of tobacco, is responsible for both tobacco product addiction (with chronic exposure) and the odor associated with tobacco. In addition to cigarettes, nicotine is found in chewing gum, transdermal patches, nasal spray, and sublingual tablets. Following its inhalation and absorption, nicotine and its metabolic products exert diverse physiologic and pharmacologic effects. This article covers the absorption and metabolism of nicotine, nicotine toxicity, pharmacologic effects of nicotine, nicotine-drug interactions, and the use of nicotine for the treatment of disease.

Lack of efficacy of a nicotine transdermal treatment on motor and cognitive deficits in Parkinson's disease

Studies assessing the efficacy of nicotine in Parkinson's disease (PD) have generated contradictory results. The controversy seems to stem from uncontrolled factors including the lack of objective measures, the practice effect in a test-retest design, and the absence of plasmatic dosage. This study aimed at further controlling these factors using transdermal nicotine in PD.

METHODS

Twenty-two nonsmoking PD patients received a transdermal nicotine treatment over 25 days in increasing titrated doses. Motor and cognitive assessments were carried out on days 11 and 25 (low-dose and high-dose assessments, respectively) and after a 14-day washout period.

RESULTS

Patients tolerated nicotine poorly. Thirteen (59%) withdrew, mostly because of acute side effects. In the remaining nine patients, nicotine neither improved nor worsened motor or cognitive functioning in comparison with 10 age, gender and education matched controls.

CONCLUSIONS

Transdermal nicotine is not effective in treating motor and cognitive deficits in PD. The results obtained with our objective measures confirm a recent double-blind, placebo-controlled study that used clinical measures. It is possible that nicotine lacks specificity in targeting critical nicotinic receptors that might be involved in PD pathophysiology. The low tolerability may be related to such a lack of specificity of nicotine, which would directly stimulate the autonomic nervous system.

Optimisation of treatment by applying programmable rate-controlled drug delivery technology

A number of programmable rate-controlled drug delivery technologies have been developed during the last two decades with the aim of regulating the rate of drug delivery, sustaining the duration of therapeutic action and/or targeting the delivery of drug to a specific tissue. As a result, several therapeutically beneficial outcomes can be achieved, such as: (i) controlled delivery of a therapeutic dose at a desirable rate of delivery; (ii) maintenance of drug concentrations within an optimal therapeutic range for prolonged duration of treatment; (iii) maximisation of efficacy-dose relationship; (iv) reduction of adverse effects; (v) minimisation of the need for frequent dose intake; and (vi) enhancement of patient compliance. The treatment of illness can thus be optimised. To gain a better understanding of how to optimise the treatment of illnesses by applying programmable rate-controlled drug delivery technologies, this article reviews the scientific concepts and technical principles behind the development of various programmable rate-controlled drug delivery systems that have been marketed or are under active development. Finally, the roles of these technologies in optimising therapeutic outcomes in nine therapeutic areas are discussed.

Effects of the transdermal nicotine patch on normalization of HDL-C and its subfractions

BACKGROUND

Smoking reduces HDL-C and its subfractions, and smoking cessation leads to normalization of these lipoproteins. Nicotine replacement therapy is an important weapon employed by those attempting to quit smoking. This study examined the effects of the transdermal nicotine patch ("patch") on lipoproteins.

METHODS

Ten male and 17 female smokers refrained from smoking for 77 days. The patch was utilized during the first 35 days and then removed for the remaining 42 days. Seven male and 9 female nonsmokers were controls.

RESULTS

HDL-C, HDL(2)-C, and HDL(3)-C levels were significantly lower in smokers when compared with controls. These differences were sustained during the initial 35 days when using the patch. Over the following 42 days, however, these lipoproteins normalized to values similar to those of control subjects. Females who quit smoking gained 2.1 kg after the patch was removed.

CONCLUSIONS

It was concluded that nicotine as administered by the transdermal nicotine patch inhibits normalization of HDL-C, HDL(2)-C, and HDL(3)-C in those who have quit smoking. Removal of the patch results in normalization of these lipoproteins. The patch appeared to prevent weight gain among female subjects.

Transdermal nicotine: single dose effects on mood, EEG, performance, and event-related potentials

A 21-mg dose of nicotine was administered transdermally to 16 overnight smoking-deprived smokers in a double-blind, placebo-controlled design. Mood ratings, electroencephalography (EEG), behavioral performance and event-related potential (ERP: P300) indices of attention and information processing speed were assessed before and 4 h after placebo/nicotine treatment. Although nicotine, relative to placebo, failed to alter mood, it increased absolute and relative power indices of EEG arousal, shortened reaction times, and increased P300 amplitudes. The results are discussed in relation to nicotine's actions on cholinergic transmission and its role in smoking behavior.

Cotinine replacement levels for a 21 mg/day transdermal nicotine patch in an outpatient treatment setting

This study examined plasma cotinine replacement levels of 56 outpatient smokers administered a 21 mg/day transdermal nicotine patch (Nicoderm CQ ). The percentage of cotinine replacement ranged from 35 to 232% (mean 107%; median 90.5%). Four subject variables were found to be significantly correlated with percentage of cotinine replacement-baseline cotinine level, prior quit attempts, gender, and the Fagerström Tolerance Questionnaire score. A two-variable model consisting of baseline cotinine level and gender provided the most powerful predictor combination. The percentage of cotinine replacement was not predictive of post-treatment smoking. The relatively high levels of cotinine replacement obtained using the Nicoderm CQ 21 mg/day patch suggest cautious use of higher dose treatment with this particular patch.

Usage patterns of transdermal nicotine when purchased as a non-prescription medicine from pharmacies

OBJECTIVE

To assess nicotine patch use in smokers who purchased the product as a non-prescription medicine from pharmacies.

DESIGN

A questionnaire administered at the time of purchase.

SETTING

Community pharmacies throughout New Zealand.

SUBJECTS

A total of 805 male and female purchasers of nicotine patches aged 18 through 87 years.

MAIN OUTCOME MEASURES

Patterns of usage including self-reported smoking history, previous quit-smoking attempts, previous and current use of transdermal nicotine and other products, side effects, and concomitant smoking.

RESULTS

Most respondents (74%) had attempted to quit smoking previously, many of whom (53%) had used a non-prescription nicotine replacement product. Approximately 60% of purchasers were first-time users. For those continuing a course of treatment, there was no evidence of use for longer than the manufacturer's recommendation (12 weeks). Twenty-eight per cent of respondents reported continuing smoking while using transdermal nicotine, although the number of cigarettes smoked was much less than in the reported smoking history. Side effects were reported by 24% of patch users in the current course, but there was no evidence of significant safety problems.

CONCLUSIONS

This survey provides preliminary data on the non-prescription usage of transdermal nicotine when purchased through pharmacies.

Determination of nicotine and cotinine in human plasma by liquid chromatography-tandem mass spectrometry with atmospheric-pressure chemical ionization interface

Here we report a sensitive liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method capable of quantifying nicotine down to 1 ng/ml and cotinine to 10 ng/ml from 1.0 ml of human plasma. The method was validated over linear ranges of 1.0-50.0 ng/ml for nicotine and 10.0-500.0 ng/ml for cotinine, using deuterated internal standards. Compounds were simply extracted from alkalinized human heparinized plasma with methylene chloride, reconstituted into a solution of acetonitrile, methanol and 10 mM ammonium acetate (53:32:15, v/v) after the organic phase was dried down, and analyzed on the LC-MS-MS, which is a PE Sciex API III system equipped with a Keystone BDS Hypersil CI8 column and atmospheric pressure chemical ionization (APCI) interface. The between-run precision and accuracy of the calibration standards were < or = 6.42% relative standard deviation (R.S.D.) and < or = 11.8% relative error (R.E.) for both nicotine and cotinine. The between-run and within-run precision and accuracy of quality controls, (2.5, 15.0, 37.5 ng/ml for nicotine and 25.0, 150.0, 375.0 ng/ml for cotinine), were < or = 6.34% R.S.D. and < or = 7.62% R.E. for both analytes. Sample stabilities in chromatography, in processing and in biological matrix were also investigated. This method has been applied to pharmacokinetic analysis of nicotine and cotinine in human plasma.

Comparison of the nicotine pharmacokinetics of Nicoderm (nicotine transdermal system) and half-hourly cigarette smoking

Nicoderm, a nicotine transdermal system (NTS), provides a continuous, transdermal delivery of nicotine and is used as an aid to smoking cessation. In contrast, cigarette smoking yields nicotine concentrations in plasma that rise and fall with each cigarette. The primary objective of this study was to compare nicotine pharmacokinetics after treatment of subjects with either the NTS or controlled smoking. Fourteen healthy adult male smokers, who smoked at least 30 cigarettes per day, were entered into a randomized crossover design trial that compared the NTS, 21 mg/day applied for 24 hours, with half-hourly smoking during the day. Subjects abstained from smoking for 2 days, and were treated for 5 days with either the NTS (daily) or controlled smoking (30 cigarettes at half-hourly intervals on days 1 and 5; ad libitum smoking on days 2-4). Blood samples were obtained frequently on days 1 and 5 for analysis of nicotine and cotinine. Pharmacokinetic comparisons showed that nicotine Cmax, area under the curve (AUC)inf, and Cavg for the NTS were lower than corresponding values for controlled smoking; Cmax and Cavg values were approximately half those of smoking. Cmax and Cavg values for cotinine were similarly lower for the NTS compared to controlled smoking. For both treatments, plasma nicotine concentrations were higher on day 5 compared to day 1. Thus, the NTS provides concentrations of nicotine that are lower than smoking.

Absorption and adverse effects following topical and oral administration of three transdermal nicotine products to dogs

To evaluate potential adverse effects from inadvertent exposure to a nicotine transdermal system or "patch", three marketed products were administered topically and orally to dogs: Nicoderm (nicotine transdermal system), with a drug reservoir and a rate-controlling membrane; Nicotinell, with a nicotine solution dispersed in a cotton gauze pad between layers of adhesive; and Niconil, with a nicotine gel matrix. Nicotine doses during topical administration ranged from 1 to 2 mg/kg/24 h for all three products, with plasma nicotine concentrations as high as 43 ng/mL. Two of the 12 topical exposures (with Nicotinell and Niconil) were associated with clinical signs (excess salivation or emesis). The oral doses from the products ranged from 2.8 mg/kg (one patch) to 13.4 mg/kg (two patches) over 25-57 h, with mean maximal plasma levels of 73 ng/mL for two patches (mean maximal level 36 ng/mL). These doses are 2-9-fold higher than oral doses reported to produce severe toxicity in children and, at the highest dose, within the known lethal range for dogs. Oral dosing of Nicotinell and Niconil (two patches per dog) produced vomiting in 2 of 12 exposures. No clinical signs were observed with either topical or oral dosing of Nicodem. These data suggest that nicotine toxicity in dogs from nicotine transdermal patches may not be as severe as might be anticipated based on nicotine content alone.

Variables affecting nicotine metabolism

Nicotine metabolism is exceedingly sensitive to perturbation by numerous host factors. To reduce the large variations and discrepancies in the literature pertaining to nicotine metabolism, investigators in future studies need to recognize and better control these host factors. Recent advances in the understanding of nicotine metabolism have suggested new approaches to elucidating underlying mechanisms of certain toxic effects associated with cigarette smoking.

Bioavailability and absorption kinetics of nicotine following application of a transdermal system

1. The absolute bioavailability and absorption kinetics of nicotine were investigated in 13 healthy adult male smokers following single and multiple applications of a nicotine transdermal system (NTS), designed to release nicotine at an approximate rate of 1.5 mg h-1 over 24 h. The absorption of nicotine from the single NTS application was calculated with reference to a simultaneous intravenous infusion (i.v.) of deuterium-labelled nicotine. 2. The mean input time (MIT) and mean absorption time (MAT) for nicotine following application of NTS for 24 h were 7.7 and 4.2 h, respectively. 3. Following NTS removal, the mean apparent nicotine elimination half-life was 2.8 h, compared with 2.0 h following i.v. nicotine, reflecting continued absorption of nicotine following NTS removal. 4. The mean amount of nicotine absorbed from the NTS after the 24 h application was 20.9 mg, which represents about 68% of the amount released from the system; the remaining 32% was lost from the system during daily activities. 5. The ratio of AUC values for the metabolite cotinine relative to nicotine was similar whether nicotine was administered transdermally or intravenously. 6. Following i.v. administration, the mean nicotine clearance was 72 l h-1 (coefficient of variation 29%). Since coefficients of variation in AUC values following NTS and i.v. treatments were similar, transdermal administration of nicotine was not associated with increased interindividual variability in plasma nicotine concentrations. 7. No significant changes were seen in the pharmacokinetics of nicotine between single and multiple applications of NTS. 8. As expected from the higher total plasma nicotine concentrations, the incidence of adverse effects was higher following simultaneous intravenous and transdermal administration of nicotine. The most frequently reported systemic side effects were nervousness and headache: mild itching was the most frequent topical effect.

Nicotine pharmacokinetics of Nicoderm (nicotine transdermal system) in women and obese men compared with normal-sized men

This study examined the effect of gender and body weight on the pharmacokinetic properties of the Nicotine Transdermal System (NTS) (Nicoderm). This NTS was applied for 24 hours to 13 normal-sized men, 13 women, and 13 obese men, all of whom were smokers who had abstained from cigarettes for the previous 24 hours. Pharmacokinetic parameters were determined during a single application of the system. The mean nicotine maximal plasma concentration (Cmax) and area under the curve (AUC) values for women did not differ significantly from those for normal-sized men. Nicotine Cmax and AUC values, however, were significantly lower in obese compared with normal-sized men; nicotine AUC was strongly correlated to body weight and body mass index. Mean apparent nicotine elimination rate constant values were not significantly different between normal-sized and obese men, but the apparent elimination rate constant value was significantly higher in women. The possible clinical significance of the differences in nicotine AUC values with body weight is discussed.