Chapter 15 Marini Pharmacotherapy

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SECTION I • Techniques and Methods in Critical Care

categories and when certain medications may be contraindicated. Examples may include evaluation of pregnancy status and avoidance of pregnancy category X medications or avoidance of inappropri- ate anticoagulation in patients who have an epidural catheter in place. Many hospital pharmacists now have a mandate to automatically adjust certain medications for those patients with renal or liver dysfunction through an approved protocol, meaning that those patients can get correct dosing from time of order verification, rather than waiting for profile review. Restricted Prescribing For the most complicated, dangerous, or expensive drugs, it makes sense to restrict prescribing to phy- sicians having sufficient familiarity, special train- ing, or qualifications. Cancer chemotherapy is a one prime example. Requiring an infectious disease consultation for infrequently used, potentially dan- gerous, or high-cost antimicrobials (e.g., ganciclovir, liposomal amphotericin B, voriconazole) provides another. A final example (although there are many more) would be to restrict inhaled prostacyclin prescribing to critical care physicians experienced in treating acute respiratory distress syndrome (ARDS). Prescribing restrictions for cost control, however, should not impede the timely use of high- value therapies. Apart from ethical concerns, doing so might only reduce the acquisition cost for the drug, not saving money if outcome consequently worsens or length of stay is increased. Eliminating Duplicate Therapy A key step toward optimizing medication use is to eliminate duplicate or overlapping therapies. It is common to see patients prescribed suboptimal doses of two or more narcotics for pain or benzo- diazepines for sedation. It is also common to see a patient with asthma or chronic obstructive pul- monary disease (COPD) have inhaled corticoste- roids wastefully administered on top of high-dose parenteral or oral corticosteroids. Antibiotic ther- apy is frequently duplicated, sometimes with det- rimental effects. For example, administration of a tetracycline with a penicillin will likely reduce the efficacy of the penicillin (because of its mecha- nism of action). Administration of azithromycin and levaquin together for community-acquired pneu- monia may not be predictably deleterious, and it also has minimal additional antimicrobial benefit.

In each case, a much better strategy is to reduce the number of drugs and to dose each to optimal effect. By doing so, fewer medications will be used, and as a result, cost, risk of adverse effects, and unwanted drug interactions will all decline. Double Dipping It is always a good idea to ask if one drug can be used to achieve two purposes. For example, in a patient with pneumonia and a urinary tract infection, is there one antibiotic or combination of antibiotics that can treat both conditions? Another example would be to select a benzodiazepine or propofol for sedation over another drug class in a patient who has had a seizure; choosing the benzodiazepine or propofol simultaneously provides a “free” anticon- vulsant. Likewise, using lactulose (vs. senna or milk of magnesia) in a patient with hepatic encephalopa- thy will provide laxative therapy while decreasing ammonia levels. Making Safer and Less Costly Choices In most cases, more than one appropriate drug alter- native exists for treatment of any given condition. When two drugs are equally efficacious, it makes sense to choose the safer alternative with fewer known adverse effects or drug–drug interactions. One example would be opting to use fluconazole or voriconazole in place of amphotericin B to reduce the risk of renal injury. Similarly, many practitioners try to avoid aminoglycosides because of their poten- tial for renal injury, even though they continue to be relatively inexpensive, often substituting a more costly antibiotic. In this case, the potential cost of renal injury will outweigh any benefit of the reduced medication cost. Sometimes, however, the safer alternative is the more inexpensive one (e.g., use of fluconazole vs. amphotericin B for certain fungal infections). Drug–drug interactions should also be consid- ered when two efficacious drug alternatives exist. Midazolam is a common sedative used in the ICU because of its relatively quick onset and short dura- tion of action (especially helpful when trying to sedate while frequently assessing neurological sta- tus). However, because of its metabolism in the liver through the cytochrome system, it has over 800 known drug interactions, 42 of which are considered a major concern. If a patient is on multiple medi- cations that interact with midazolam, it may make more sense to use propofol or dexmedetomidine