Like any other process in health care, writing a prescription should be based on a series of rational steps.
1. Make a specific diagnosis: Prescriptions based merely on adesire to satisfy the patient’s psychological need for some type of therapy are often unsatisfactory and may result in adverse effects. A specific diagnosis, even if it is tentative, is required to move to the next step. For example, in a patient with a prob-able diagnosis of rheumatoid arthritis, the diagnosis and the reasoning underlying it should be clear and should be shared with the patient.
2. Consider the pathophysiologic implications of the diagnosis: Ifthe disorder is well understood, the prescriber is in a much better position to offer effective therapy. For example, increasing knowl-edge about the mediators of inflammation makes possible moreeffective use of nonsteroidal anti-inflammatory drugs (NSAIDs) and other agents used in rheumatoid arthritis. The patient should be provided with the appropriate level and amount of informa-tion about the pathophysiology. Many pharmacies, websites, and disease-oriented public and private agencies (eg, American Heart Association, American Cancer Society, Arthritis Foundation) provide information sheets suitable for patients.
3. Select a specific therapeutic objective: A therapeutic objec-tive should be chosen for each of the pathophysiologic pro-cesses defined in the preceding step. In a patient with rheumatoid arthritis, relief of pain by reduction of the inflam-matory process is one of the major therapeutic goals that iden-tifies the drug groups that will be considered. Arresting the course of the disease process in rheumatoid arthritis is a differ-ent therapeutic goal, which might lead to consideration of other drug groups and prescriptions.
4. Select a drug of choice: One or more drug groups will be sug-gested by each of the therapeutic goals specified in the preceding step. Selection of a drug of choice from among these groups fol-lows from a consideration of the specific characteristics of the patient and the clinical presentation. For certain drugs, charac-teristics such as age, other diseases, and other drugs being taken are extremely important in determining the most suitable drug for management of the present complaint. In the example of the patient with probable rheumatoid arthritis, it would be impor-tant to know whether the patient has a history of aspirin intoler-ance or ulcer disease, whether the cost of medication is an especially important factor and the nature of the patient’s insur-ance coverage, and whether there is a need for once-daily dosing. Based on this information, a drug would probably be selected from the NSAID group. If the patient is intolerant of aspirin and does not have ulcer disease but does have a need for low-cost treatment, ibuprofen or naproxen would be a rational choice.
5. Determine the appropriate dosing regimen: The dosingregimen is determined primarily by the pharmacokinetics of the drug in that patient. If the patient is known to have disease of the organs required for elimination of the drug selected, adjustment of the average regimen is needed. For a drug such as ibuprofen, which is eliminated mainly by the kidneys, renal function should be assessed. If renal function is normal, thehalf-life of ibuprofen (about 2 hours) requires administration three or four times daily. The dose suggested in this book, drug handbooks, and the manufacturer’s literature is 400–800 mg four times daily.
6. Devise a plan for monitoring the drug’s action and deter mine an end point for therapy: The prescriber should be ableto describe to the patient the kinds of drug effects that will bemonitored and in what way, including laboratory tests (ifnecessary) and signs and symptoms that the patient shouldreport. For conditions that call for a limited course of therapy (eg, most infections), the duration of therapy should be made clear so that the patient does not stop taking the drug prematurely and understands why the prescription probably need notbe renewed. For the patient with rheumatoid arthritis, the need forprolongedperhaps indefinite—therapyshouldbeexplained. The prescriber should also specify any changes inthe patient’s condition that would call for changes in therapy.For example, in the patient with rheumatoid arthritis, development of gastrointestinal bleeding would require an immediate change in drug therapy and a prompt workup of the bleeding.Major toxicities that require immediate attention should beexplained clearly to the patient.
7. Plan a program of patient education: The prescriber andother members of the health team should be prepared to repeat,extend, and reinforce the information transmitted to thepatient as often as necessary. The more toxic the drug prescribed, the greater the importance of this educational program.The importance of informing and involving the patient in eachof the above steps must be recognized, as shown by experiencewith teratogenic drugs . Many pharmacies routinely provide this type of information with each prescription filled, but the prescriber must not assume that this will occur.