Repeat-dose drugs removed

Some compounds are stored in the body in specific tissues. Such storage effectively removes the material from circulation and thus decreases the toxicity of the compound. Repeated doses of a toxic substance may be taken up and subsequently stored without apparent toxicity until the storage receptors become saturated then toxicity suddenly occurs. In some cases, the stored compound may be displaced from its storage receptor by another compound that has an affinity for the same receptor. Examples of this phenomenon are the displacement of antidiabetic sul-fonylureas by sulfonamides and the ability of antimalarial drugs such as quina-crine (atabrine) and primaquine to displace each other (Loomis, 1978). A special danger in such cases is that compounds may have escaped detoxifying metabolism while stored in the body, and that their toxicity may be potent and prolonged when released. 

TABLE Ml. SOME DRUGS REMOVED BY REPEAT-DOSE ACTIVATED CHARCOAL ... 

D. Enhanced elimination. Symptoms usually abate within several hours and can be managed effectively with intensive supportive care, so there is little to be gained from accelerated drug removal by dialysis or hemoperfusion. The use of repeat-dose activated charcoal has not been studied. 

D. Enhanced elimination. There is no clinical experience with extracorporeal drug removal for these agents. Terazosin and doxazosin are long-acting and eliminated 60% in feces thus, repeat-dose activated charcoal may enhance their elimination. 

B. Repeated doses of activated charcoal may be indicated to enhance elimination of some drugs if (1) more rapid elimination will benefit the patient (and the benefits outweigh the risks of repeated doses see IV.C and V.C, below), and (2) more aggressive means of removal (eg, hemodialysis orhemoperfu-sion) are not immediately indicated or available (see p 57). However, it has not been proven to improve patient outcome in clinical studies. 

Epinephrine 1 1000, 0.2 to 0.5 mg (0.2 to 0.5 mL) SC is the primary treatment. In children, administer 0.01 mg/kg or 0.1 mg. Doses may be repeated every 5 to 15 minutes if needed. A succession of small doses is more effective and less dangerous than a single large dose. Additionally, 0.1 mg may be introduced into an injection site where the offending drug was administered. If appropriate, the use of a tourniquet above the site of injection of the causative agent may slow its absorption and distribution. However, remove or loosen the tourniquet every 10 to 15 minutes to maintain circulation. 

---