Topical route

The nurse considers the following points when administering dru > by the topical route ... 

Where an unusual excipient is chosen, or where an established excipient is chosen for a dosage form that results in its administration by a novel route of administration, then additional data will need to form part of the application. In effect, a novel excipient will need to be supported by data similar to those required for a new drug, with full supporting data including composition, function, and safety. Novel excipients include the components of the matrix in prolonged release products, new propellants, and new permeability enhancers. The exception to this need for extensive supporting data would be for a material already approved for food use and administered by the oral route or a material already approved for cosmetic use with a topical route of administration. In all cases the quality of the excipients has to be described adequately and shown to be satisfactory (which will depend on its role). 

Topical routes of drug administration are where the drug is applied directly to the site of action. Many medicines are applied directly for example, hydrocortisone can be rubbed into the skin to relieve a local area of inflammation. The anticholinesterase neostigmine is dropped directly onto the eye surface to relieve glaucoma, a condition characterised by raised intra-ocular pressure which if untreated can lead to blindness. 

The answer is a. (Hardman, pp 1143-1144.) Polymyxin B is poorly absorbed by the oral route. It is primarily administered by the topical route for the treatment of infections of the skin, mucous membranes, eye, and ear. Penicillin G can be administered both orally and parenterally. Did oxacillin is only given by the oral route. Carbenicillin and streptomycin are administered only by the parenteral route. 

Mezei, M. and Gulasekharam, V, Liposomes a selective drug delivery system for the topical route of administration gel dosage form. J. Pharm. Pharmacol., 34,473-74, 1982. 

Mezei, M. and Gulasekharam, V., Liposomes — a selective drug delivery system for the topical route of administration lotion dosage form. Life ScL, 26, 1473-77, 1980. Fresta, M. and Pughsi, G., Survival rate improvement in a rat ischemia model by long circulating liposomes containing cytidine-51-diphosphate choline. Life ScL, 61, 1227-35, 1997. 

Figure 19.7 Experimental procedure forthe assessment of photocytotoxicity (MTT assay) and photo-genotoxicity (comet assay) on reconstructed epidermis. Drugsorformulationscan be applied on the skin surface (topical route) or provided in the culture medium (systemic route see [76]).

They are given by oral, parenteral and topical route. Oral bioavailabiHty of synthetic cortico-steroids is high. Hydrocortisone after oral administration undergoes extensive first pass metabolism in liver. 

In the general chapter on microbial attributes of nonsterile pharmaceutical products, the guidance suggests that the presence of microbial contaminants in nonsterile products [25] can reduce or inactivate the therapeutic activity of the product and has the potential to adversely effect the health of the patients and recommends manufacturers to ensure that contamination levels are as low as possible for finished dosage forms. Microbial enumeration limits for raw materials (total aerobic microbial count and total combined yeasts and molds count) and finished dosage forms are described. For inhalation, nasal, and topical routes of administration, tests for total aerobic microbial count and total combined and yeast and mold count,... 

Depolymerizing Enzymes. Depolymerizing enzymes belong to a special class of hydrolases which cleave peptide bonds using water as co-substrate. They are used widely by the topical route as antiinflammatory agents. They reduce inflammation and edema by digesting and dissolving the proteinaceous debris found in inflammatory exudates (179). 

The skin offers a number of special opportunities to the therapist. For example, the topical route of administration is especially appropriate for diseases of the skin, though some dermatologic diseases respond as well or better to drugs administered systemically. 

Acyclovir is used in herpes simplex infection and should be administered as early as possible after the appearance of symptoms by the intravenous, oral, or topical route. Prolonged treatment reduces the recurrence but sudden withdrawal is dangerous, as the disease may recur. Acyclovir improves the healing of herpes zoster lesions and reduces pain. 

An advantage of transdermal delivery in eliminating first-pass metabolism in evident in these comparative studies of the delivery of DIL by intravenous, oral, and topical routes. deAcDIL is the primary metabolite of DIL identified in oral delivery (12, 13). Typical plasma profiles are compared in Figure 4 for oral and topical delivery. 

The topical route is the most common method to administer a medication to the eye. Introducing the drag directly to the conjunctival sac localizes drag effects, facilitates drag entiy that is otherwise hard to achieve with systemic delivery and avoids first-pass metabolism. The physiological factors affecting topical drag delivery and the approaches under development to optimize this type of delivery are described in detail below. 

Pharmacokinetics Administration can be by an intravenous, oral, or topical route. The efficacy of topical applications is doubtful. The drug distributes well throughout the body, including the cerebrospinal fluid. Acyclovir is partially metabolized to an inactive product. Excretion into the urine occurs both by glomerular filtration and tubular secretion. Acyclovir accumulates in patients with renal failure. 

In 1951-1952, Sulzberger et al. showed that systemically - but not topically -applied cortisone acetate was effective in the treatment of eczema and other der-matitides, whereas hydrocortisone was effective with both routes of administration [8,9]. Because the topical route promised a relative freedom from troublesome systemic side effects (e.g., salt retention). Schering recognized the need for an effective synthesis of the latter. 

Pharmaceuticals showing poor systemic exposure from topical routes in humans may not need studies by the oral route to assess the carcinogenic potential to internal organs. 

Oral administration of the test compounds in this model did not add value to the results from the topical route of administration. 

Mezei, M., and Gulasekharam, V. (1980), Liposomes A selective drag delivery system for topical route of administration. I-lotion dosage form, Life Sci., 26,1473-14777. 

It has been shown in a number of studies that the incorporation of drug in o/w nanosized emulsions significantly increased the absorption of the drug when compared with the equivalent aqueous solution administered orally [132-135], However, the use of emulsions for oral application is limited since other attractive alternatives, such as self-emulsifying oil delivery systems, which are much less sensitive and easy to manufacture, are available [136,137], Thus the potential of nanosized emulsions after administration with parenteral and traditional nonparenteral topical routes such as ocular, percutaneous, and nasal is covered in this section. 

Systemic steroids are also the cause of numerous negligence claims.These drugs have side effects that can result in serious injury, even death, and consequently must be used conservatively. Systemically administered drugs, with their risk of systemic complications, should not be used if a topical route of administration suffices, and practitioners must be prepared to justify the selection of a systemic route of administration when complications result and a topical route of administration initially was not used. Whenever systemic steroids are prescribed, practitioners must warn patients of side effects, monitor patients adequately so that preventable injuries can be detected, and document the care rendered. 

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