Prescribing an inappropriate drug for a particular patient often results from failure to recognize contraindications imposed by other diseases the patient may have, failure to obtain information about other drugs the patient is taking (including over-thecounter drugs), or failure to recognize possible physicochemical incompatibilities between drugs that may react with each other. Contraindications to drugs in the presence of other diseases or pharmacokinetic characteristics are listed in the discussions of the drugs described in this book. The manufacturer’s package insert usually contains similar information. Many of the important drug interactions are listed in Chapter 66 of this book as well as in package inserts.
Physicochemical incompatibilities are of particular concern when parenteral administration is planned. For example, certain insulin preparations should not be mixed. Similarly, the simultaneous administration of antacids or products high in metal content may compromise the absorption of many drugs in the intestine, eg, tetracyclines. The package insert and the Handbook on Injectable Drugs (see References) are good sources for this information.
Seventy percent of prescriptions in the USA are now E-prescribed. Congress has passed legislation related to E-prescribing, including Medicare Improvement for Patients and Providers Act (MIPPA) and the Medicare and Medicaid Electronic Health Record Incentive Program or the “meaningful use program.” E-prescribing provides an electronic flow of information between the prescriber, intermediary, pharmacy, and health plan. The health plan can provide information on patient eligibility, formulary, benefits, costs, and sometimes, a medication history. The prescriber selects the medication, strength, dosage form, quantity, and directions for use and the prescription is transmitted to the pharmacy where the appropriate data fields are populated. The pharmacist reviews the order and, if appropriate, dispenses the prescription. The electronic system must be Health Insurance Portability and Accountability Act (HIPAA)-compliant, and there is often a business association agreement between the parties involved.
Prescribers can obtain decision support information such as disease-drug and drug-drug interaction information or cost information prior to prescribing as part of the health plan information. Prescriptions can be clear in their writing, but pull-down drug lists can create new errors. Prescription renewals can be processed electronically and drug misuse or abuse may be identifiable. Theoretically, time to process prescription orders should be reduced and patients would have their medication ready when they arrive at the pharmacy.
The DEA has issued rules for e-prescribing of controlled substances. Currently, only registered prescribers can e-prescribe, and there will be several independent identification proofing sources required: a unique pin number, or retinal scan, or a finger print. The objective is to prevent drug diversion. DEA registrants, including pharmacies and physicians, can order controlled drugs via computer using a specific form once they are certified (Controlled Substances Ordering System, CSOS).
Compliance (also called adherence) is the extent to which patients follow treatment instructions. There are four types of noncompliance leading to medication errors and increased health care costs as given below: 1. The patient fails to obtain the medication. Some studies suggest that one third of patients never have their prescriptions filled. Patients usually leave the hospital without obtaining their discharge medications because the hospital is not reimbursed for them by the insurer; others leave the hospital without having their prehospitalization medications resumed. In many cases, patients cannot afford the medications prescribed.
2.
The patient fails to take the medication as prescribed. Examples include wrong dosage, wrong frequency of administration, improper timing or sequencing of administration, wrong route or technique of administration, or taking medication for the wrong purpose. This usually results from inadequate communication between the patient, the prescriber, and the pharmacist.
3.
The patient prematurely discontinues the medication. This can occur, for instance, if the patient incorrectly assumes that the medication is no longer needed because the bottle is empty or symptomatic improvement has occurred.
4.
The patient (or another person) takes medication inappropriately. For example, the patient may share a medication with others for any of several reasons.