Patch spraying system

The use of a patch spraying system based on a treatment map requires ... 

Much of the field trials work with spatially variable (patch) spraying systems has used herbicides, and has shown that typically some 50% of the chemical needed for grass weed control in cereal crops can be saved. Other weed species are also known to be patchy (cleavers and thistles), and therefore overall estimated savings in herbicide use are commonly around 25%. Research work is currently examining the scope for the spatially variable application of... 

Lutman, P.J.W., Rew, L.J., Cussans, G.W., Miller, P.C.H., Paice, M.E.R. and Stafford, J.V. (1998) Development of a patch spraying system to control weeds in winter wheat. HGCA Project Report No. 158. Home-Grown Cereals Authority, London. 

Weed populations tend to be veiy patchy over the field. It is very time-consuming to map weeds manually. Currently, automated systems for weed mapping are being developed. One option for some of the major weeds such as wild oats (because weeds spread by only a few metres per year) is to assess the weeds in early suimner before harvest and to produce a map. This map can then be used for patch spraying in future years. 

Other delivery systems are transdermal patches, metered dose inhalers, nasal sprays, implantable devices, and needle-free injections. A description of needleless injection is given in Exhibit 5.16. 

F%.1 Venous blood concentrations in nanograms of nicotine per miUimeter of blood as a function of time for various nicotine delivery systems. Data on the cigarette delivering about 1 mg nicotine (filled square), oral snuff delivering 3.6 mg (filled circle), and 4 mg nicotine gum (star) are from those published by Benowitz et al. (1988). Data on 1 mg nicotine nasal spray (filled triangle) are from Schneider et al. (1996). Data on 21 mg transdermal nicotine patch (open square) are from Benowitz (1993). Data on the 4 mg nicotine lozenge (open circle) are from Choi et al. (2003)... 

Transderm al Easy Convenient No first-pass metabolism Local or systemic effects Irritation Potent drugs only Absorption affected by site of application Hard to administer Solutions, lotions, sprays, gels, ointments, creams, powders, patches... 

There are several approaches to help patients stop smoking. One approach is replacement therapy with nicotine in the form of gum, transdermal patch, nasal spray, or inhaler. All these forms have low abuse potential and are effective in patients motivated to stop smoking. Their action derives from slow absorption of nicotine that occupies 4 2 receptors in the central nervous system and reduces the desire to smoke and the pleasurable feelings of smoking. 

In addition to traditional dermal and transdermal delivery formulations, such as creams, ointments, gels, and patches, several other systems have been evaluated. In the pharmaceutical semisolid and liquid formulation area,these include sprays, foams, multiple emulsions, microemulsions, liposomal formulations, transfersomes, niosomes, ethosomes, cyclodextrins, glycospheres, dermal membrane structures, and microsponges. Many of these novel systems use vesicles to modulate drug delivery. Novel transdermal... 

Note Smoking cessation therapy has various delivery systems. These include transdermal patches, chewing gum, nasal spray, inhaler, and oral forms... 

Side effects specific to nicotine delivery systems are mainly caused by local irritation at the site of administration. For example, nausea, indigestion, sore gums, and mouth ulceration may occur when using the gum. The patches may cause skin irritation, which is characterized by erythema, pruritus, edema, and rarely, vesicles. The nasal spray may cause irritation of the nasal mucosa, sneezing, coughing, and lacrimation, although tolerance to these effects develops rapidly with continued use. Side effects from the inhaler include mild mouth and throat irritation and coughing (181). 

Nicotine bioavailability also varies with the delivery system. The reported bioavailability from the nasal spray and transdermal patch is 53% and 82%, respectively (93,184). In nicotine polacrilex gum, nicotine is bound to an ion exchange resin and is released only by chewing. Nicotine bioavailability, therefore, is dependent on the vigor, rapidity, and duration of chewing. Of the 10 mg in each cartridge of a nicotine inhaler, only 4 mg is actually delivered from the device to the oral mucosa and is available for absorption. 

Rarely have complications from CS exposure included haemoptysis and haematemesis (Anderson et al., 1996). A case of multisystem hypersensitivity reaction characterized by delayed development of cutaneous rash, pneumonitis, hypoxaemia, hepatitis and hypereosinophilia, with rapid response to corticosteroids, was described in a man heavily exposed to CS solution spray. The authors ascribed this to a systemic allergic reaction patch testing confirmed sensitization to CS (Hill et al., 2000). The possible abuse and complications from illegal drugs should be considered where clinical suspicions exists (Hayman and Berkely, 1971). Physicians should be aware of the possible contribution from formulation constituents some may exacerbate effects known to be produced by RCAs (e.g. eye injury and skin irritation) and others may introduce additional toxicological factors (such as the development of carbon monoxide intoxication from the absorption and metabolism of dichloromethane as a formulation solvent). 

Methods by which dose and mixtures of spray chemicals can be delivered at different controlled rates have been discussed earlier in this section. For spatially variable (patch) applications, Miller et al. (1997) summarised the performance requirements of the application system as follows ... 

An important feature of using these manual sprayers is that it is possible to do selective spot treatments, for example, confining the application of herbicides to patches of weeds. Also, where there is concern about downwind spray drift, placement of the nozzle nearer to the target and using a low pressure can enable treatments closer to a sensitive area. In conjunction with an attractant such as molasses or protein hydrolysate, insecticide bait sprays have been used in discrete spots for fruitfly control. Knapsack sprayers are often used in difficult terrain where access to vehicles is difficult or impossible. However, the lack of water in some situations, and the high requirement for labour, have created a demand for alternative application systems (see below). 

The feasibility of employing fluorescent tracers and video imaging analysis to quantify dermal exposure to pesticide applicators has been demonstrated under realistic field conditions. Six workers loaded a tracer with the organophosphate pesticide, diazinon, into air blast sprayers, and conducted normal dormant spraying in pear orchards. They were examined prior to and immediately after the application. UV-A illumination produced fluorescence on the skin surface, and the pattern of exposure was digitized with a video imaging system. Quantifiable levels of tracer were detected beneath cotton coveralls on five workers. The distribution of exposure over the body surface varied widely due to differences in protective clothing use, work practices and environmental conditions. This assessment method produced exposure values at variance with those calculated by the traditional patch technique. 

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