This section provides detailed descriptions of antidotes and other therapeutic agents used in the management of a poisoned patient. For each agent, a summary is provided of its pharmacologic effects, clinical indications, adverse effects and contraindications, use in pregnancy, dosage, available formulations, and recommended minimum stocking levels for the hospital pharmacy (for availability within 60 minutes) and emergency department (for immediate availability).
Use of antidotes in pregnancy. It is always prudent to avoid or minimize drug exposure during pregnancy, and physicians are often reluctant to use an antidote for fear of fetal harm. This reluctance, however, must be tempered with a case-by-case risk-benefit analysis of the use of the particular therapeutic agent. An acute drug overdose or poisoning during pregnancy may threaten the life of the mother as well as the life of the fetus, and the antidote or therapeutic agent, despite unknown or questionable effects on the fetus, may have a lifesaving benefit. The inherent toxicity and large body burden of the drug or toxic chemical involved in the poisoning may far exceed those of the therapeutic agent or antidote.
For most of the agents discussed in this section, little or no information is available about their use in pregnant patients. The Food and Drug Administration (FDA) established five categories (A, B, C, D, and X) of required labeling to indicate the potential for teratogenicity (Table III–1). The distinction between categories depends mainly on the amount and reliability of animal and human data and the risk-benefit assessment for the use of a specific agent. This has led to confusion, with the misbelief that risk increases in a predictable way from Category A to Category X. Note that the categorization may also be based on anticipated chronic or repeated use and may not be relevant to a single use or brief antidotal treatment. Note: In 2015, the Pregnancy and Lactation Labeling Final Rule went into effect, which will replace the former FDA A-X pregnancy categories with narrative sections to include Pregnancy and Lactation with subsections addressing risk summary, clinical considerations, and data.
Hospital stocking. The hospital pharmacy should maintain a medical staff-approved stock of antidotes and other emergency drugs. Surveys of hospitals consistently have demonstrated inadequate stocks of antidotes. Many antidotes are used only infrequently, have a short shelf life, or are expensive. There have also been disruptions and delays in the supply of antidotes from manufacturers as well as discontinuation of some products (eg, multiple-dose glucagon). The optimal and most cost-effective case management of poisonings, however, requires having adequate supplies of antidotes readily available. Fortunately, only a minimal acquisition and maintenance cost is required to stock many of these drugs adequately. Other cost reduction strategies may include employment of an institutional approval and utilization review process (eg, requiring local poison center approval for the use of selected costly antidotes), arrangements with suppliers to replace expired and unused antidotes (note that some manufacturers have such a policy), ...