Oral route

Acute intoxication with DHBs occurs mainly by the oral route symptoms are close to those induced by phenol poisoning including nausea, vomiting, diarrhea, tachypnea, pulmonary edema, and CNS excitation with possibiUty of seizures followed by CNS depression. Convulsions are more frequent with catechol as well as hypotension due to peripheral vasoconstriction. Hypotension and hepatitis seem more frequent with hydroquinone and resorcinol. Methemoglobinemia and hepatic injury may be noted within a few days after intoxication by DHBs. 

The efficacy of florfenicol in vivo was determined by measuring the dose required to obtain values for protection from infection in 50% of the animals (PD q) against 10 chloramphenicol-resistant strains and two chloramphenicol-sensitive isolates. Florfenicol, chloramphenicol, and thiamphenicol were evaluated concurrendy against each strain. Against sensitive Enterobacter 50 subcutaneous and oral routes were similar for dorfenicol and... 

Fig. 3. Schematic representation showing the anatomical basis for differences in the quantitative supply of absorbed material to the Hver. By swallowing (oral route), the main fraction of the absorbed dose is transported direcdy to the Hver. FoUowing inhalation or dermal exposure, the material passes to the pulmonary circulation and thence to the systemic circulation, from which only a portion passes to the Hver. This discrepancy in the amount of absorbed material passing to the Hver may account for differences in toxicity of a material by inhalation and skin contact, compared with its toxicity by swallowing, if metaboHsm of the material in the Hver is significant in its detoxification or metaboHc activation.

The pharmacology of penicillins differs markedly from compound to compound but has been well reviewed (57). The majority of derivatives, including penicillin G and the antipseudomonal penicillins, ate unstable in gastric acid and ate not available orally. The isoxazolyl penicillins ate relatively acid stable but not consistendy well absorbed by the oral route. Nafcillin and oxacillin ate poody absorbed orally cloxacillin, dicloxacillin, and ducloxacillin ate more teUable. Penicillin V, ampicillin, and patticulady amoxicillin ate relatively well absorbed orally. Esters of ampicillin such as bacampicillin, pivampicillin, and talampicillin improve the level of oral absorption of ampicillin to that achieved by amoxicillin. Absorption can be diminished by food after oral adruinistration, however, and peak blood levels, usually achieved after 1 to 2 h, ate somewhat delayed after ingestion of food. 

Oral. The oral route for dmg dehvery includes the gastrointestinal (GI) tract and the oral cavity including the buccal mucosa. The buccal mucosa is considered separately because of differences in the approach to dmg dehvery via this route. 

Carcinogenicity of DGEBPA or DGEBPA-based resins, as measured by topical appHcation, has not been shown by a majority of the studies (45). Advanced DGEBPA resins exhibit low systemic toxicity either by dermal or oral routes and inhalation of these resins is unlikely because of low volatihty. The acute oral LD q in rats has been reported to be >2000 mg/kg (46). Acute dermal studies show these materials have alow potential for absorption through the skin in acutely toxic amounts. No evidence of carcinogenicity has been found in animals or humans for advanced DGEBPA resins (47,48). 

Several mucolytics reduce the viscosity of mucus by cleaving the disulfide bonds that maintain the gel stmcture. AJ-Acet l-L-cysteine [616-91 -1] (19), introduced in 1963, and mesna [19677-45-5] (20), developed in Europe in the early 1970s (20,21), are effective compounds in this class. Whereas most mucolytics must be adrninistered by aerosol, carbocysteine [638-23-6] (21), which contains a derivatized sulfhydryl group, has shown activity by the oral route (22,23). However, carbocysteine does not reduce mucus viscosity, as does acetylcysteine, but appears to have a direct action on mucus glycoprotein production (24). 

The toxic action of bromine is similar to that of chlorine and can cause physiological damage to humans through inhalation and oral routes. It is an irritant to the mucous membranes of the eyes and upper respiratory tract. Severe exposures may result in pulmonary edema. Chronic exposure is similar to therapeutic ingestion of excessive bromides. 

FIGURE 8.23 Kinetic profiles of the plasma concentrations of three different drags taken by the oral route. If absorption is rapid, toxic effects may ensue (red line). If too slow, a therapeutically effective level may not be attained (blue line). 

The oral route is the most frequent route of drug administration and rarely causes physical discomfort in patients. Oral drug forms include tablets, capsules, and liquids. Some capsules and tablets contain sustained-release drag s, which dissolve over an extended period of time. Administration of oral dru is relatively easy for patients who are alert and can swallow. 

The nurse should give antitubercular dragp by die oral route and on an empty stomach, unless gastric upset occurs. If gastric upset occurs, it is important to notify die primary healdi care provider before the next dose is given. 

Which of the following adverse reactions would die nurse expect in a patient receiving acyclovir by the oral route ... 

Decongestants are used to treat the congestion associated with rhinitis, hay fever, allergic rhinitis, sinusitis, and the common cold. In addition, they are used in adjunctive therapy of middle ear infections to decrease congestion around the eustachian tube Nasal inhalers may relieve ear block and pressure pain during air travel. Many can be administered orally as well as topically, but topical application is more effective than the oral route. 

Amino acids promote the production of proteins, enhance tissue repair and wound healing, and reduce the rate of protein breakdown. Amino acids are used in certain disease states, such as severe kidney and liver disease, as well as in TPN solutions. (See the last section of this chapter for a more detailed discussion of TPN.) TPN may be used in patients with conditions such as impairment of gastrointestinal absorption of protein, in patients with an increased requirement for protein, as seen in those with extensive bums or infections, and in patients with no available oral route for nutritional intake ... 

Obviously, if you wish to treat a skin condition or infection, a preparation that can be applied topically would be the preferred option. Similarly, inhalation would be the first choice if trying to treat a pulmonary or bronchial condition, such as asthma. Dermal application would also be the first choice for localized tissue treatments (e.g. muscle injury), provided that the drug can be absorbed through the skin. However, in most other situations it is necessary for drugs to enter the bloodstream in order for them to be transported to their site of action. This is most commonly achieved by ingestion, or by intravenous (i.v.), intramuscular (i.m.) or subcutaneous (s.c.) injection when the oral route is not suitable. 

The pretreatment of MH-susceptible patients with oral or intravenous dantrolene prior to surgery in order to avoid a crisis is controversial. Most physicians do not recommend prophylactic pretreatment except in patients who have had a previously documented episode. However, if pretreatment is desired, it is recommended that therapy be begun with intravenous dantrolene in a dose of 2 mg/Kg just prior to induction of anesthesia. This prevents the uncertainty of predictive blood values associated with the use of the oral route. The adverse effects of intravenous dantrolene prophylaxis include phlebitis and tissue necrosis. Patients who receive prophylactic treatment with oral dantrolene often complain of incapacitation, gastrointestinal irritation, prolonged drowsiness, and clinically significant respiratory muscle weakness. 

Estimates of exposure levels posing minimal risk to humans (Minimal Risk Levels or MRLs) have been made for methyl parathion. An MRL is defined as an estimate of daily human exposure to a substance that is likely to be without an appreciable risk of adverse effects (noncarcinogenic) over a specified duration of exposure. MRLs are derived when reliable and sufficient data exist to identify the target organ(s) of effect or the most sensitive health effect(s) for a specific duration within a given route of exposure. MRLs are based on noncancerous health effects only and do not consider carcinogenic effects. MRLs can be derived for acute, intermediate, and chronic duration exposures for inhalation and oral routes. Appropriate methodology does not exist to develop MRLs for dermal exposure. 

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