The effect of smoking nicotine tobacco versus smoking deprivation on motion sickness

BACKGROUND: The experienced smoker maintains adequate nicotine levels by 'puff-by-puff self-control' which also avoids symptomatic nauseating effects of nicotine overdose. It is postulated that there is a varying 'dynamic threshold for nausea' into which motion sickness susceptibility provides an objective toxin-free probe. Hypotheses were that: (i) nicotine promotes motion sickness whereas deprivation protects; and (ii) pleasurable effects of nicotine protect against motion sickness whereas adverse effects of withdrawal have the opposite effect. METHODS: Twenty-six healthy habitual cigarette smokers (mean±SD) 15.3±7.6cigs/day, were exposed to a provocative cross-coupled (coriolis) motion on a turntable, with sequences of 8 head movements every 30s. This continued to the point of moderate nausea. Subjects were tested after either ad-lib normal smoking (SMOKE) or after overnight deprivation (DEPRIV), according to a repeated measures design counter-balanced for order with 1-week interval between tests. RESULTS: Deprivation from recent smoking was confirmed by objective measures: exhaled carbon monoxide CO was lower (P<0.001) for DEPRIV (8.5±5.6ppm) versus SMOKE (16.0±6.3ppm); resting heart rate was lower (P<0.001) for DEPRIV (67.9±8.4bpm) versus SMOKE (74.3±9.5bpm). Mean±SD sequences of head movements tolerated to achieve moderate nausea were more (P=0.014) for DEPRIV (21.3±9.9) versus SMOKE (18.3±8.5). DISCUSSION: Tolerance to motion sickness was aided by short-term smoking deprivation, supporting Hypothesis (i) but not Hypothesis (ii). The effect was was approximately equivalent to half of the effect of an anti-motion sickness drug. Temporary nicotine withdrawal peri-operatively may explain why smokers have reduced risk for postoperative nausea and vomiting (PONV).

Electrospun medicated shellac nanofibers for colon-targeted drug delivery

Medicated shellac nanofibers providing colon-specific sustained release were fabricated using coaxial electrospinning. A solution of 7.5 g shellac and 1.5 g of ferulic acid (FA) in 10 mL ethanol was used as the core fluid, and a mixture of ethanol and N,N-dimethylformamide (8/10 v/v) as the shell. The presence of the shell fluid was required to prevent frequent clogging of the spinneret. The diameters of the fibers (D) can be manipulated by varying the ratio of shell to core flow rates (F), according to the equation D = 0.52F−0.19. Scanning electron microscopy images revealed that fibers prepared with F values of 0.1 and 0.25 had linear morphologies with smooth surfaces, but when the shell fluid flow rate was increased to 0.5 the fiber integrity was compromised. FA was found to be amorphously distributed in the fibers on the basis of X-ray diffraction and differential scanning calorimetry results. This can be attributed to good compatibility between the drug and carrier: IR spectra indicated the presence of hydrogen bonds between the two. In vitro dissolution tests demonstrated that there was minimal FA release at pH 2.0, and sustained release in a neutral dissolution medium. The latter occurred through an erosion mechanism. During the dissolution processes, the shellac fibers were gradually converted into nanoparticles as the FA was freed into solution, and ultimately completely dissolved.

Nanofibers fabricated using triaxial electrospinning as zero order drug delivery systems

A new strategy for creating functional trilayer nanofibers through triaxial electrospinning is demonstrated. Ethyl cellulose (EC) was used as the filament-forming matrix in the outer, middle, and inner working solutions and was combined with varied contents of the model active ingredient ketoprofen (KET) in the three fluids. Triaxial electrospinning was successfully carried out to generate medicated nanofibers. The resultant nanofibers had diameters of 0.74 ± 0.06 μm, linear morphologies, smooth surfaces, and clear trilayer nanostructures. The KET concentration in each layer gradually increased from the outer to the inner layer. In vitro dissolution tests demonstrated that the nanofibers could provide linear release of KET over 20 h. The protocol reported in this study thus provides a facile approach to creating functional nanofibers with sophisticated structural features.