Factors To Be Considered During Therapeutic Drug Monitoring

Factors To Be Considered During Therapeutic Drug Monitoring

Several steps are required in the systematic process of drug monitoring. These steps are as follows: 

Collection of Patient Data 

To monitor therapy effectively, one must have an adequate data-base of patient information. The data-base is central to the monitoring process and consists of factors such as: 

• Demographic data about the patient. 

• Chief complaints.

• Past medical and drug history. 

• History of present illness. 

• Physical examination. 

• Social history. 

• Laboratory data. 

A data base is dynamic and changing with the progress of the patient’s disease and drug therapy and requires continuous review and reevaluation. 

The most important source of information is the patient's medical record. The reviewing of the nurse’s progress notes in the medical record may provide a record of the patient’s day-to-day physiologic and psychological changes that are particularly helpful in monitoring for side effects of drug therapy. Once patient information has been reviewed, data relevant to drug therapy monitoring should be summarized and organized into a useful format. The information collected may be placed on monitoring sheets of various designs or may be computerized or important data may be committed to memory by the monitoring pharmacist.

Statement of Therapeutic Goals 

The pharmacist must familiarize himself with the therapeutic goals that have been set for a patient in association with the physician. This knowledge is necessary for the pharmacist to assess the therapy and determine the clinical importance of problems that are identified. Pharmacists should participate when treatment plans are being established. This can help to establish the therapeutic goals. The therapeutic goals can also be derived by reviewing the physicians admitting notes, plan of therapy, and nursing care plan. The goal of therapy for the patient’s pneumonia would be to cure the infectious process; the therapeutic goal for congestive heart failure would not be to cure but rather to restore cardiac function to normal limits. 

Problem-Oriented Medical Record (POMR) systems are also beneficial for setting the therapeutic goal. In this system, each patient problem is approached by supplying subjective (symptomatic) and objective information concerning it as well as an assessment of the problem and plan of action. 

When the goals of the therapy have been well established and defined, then orderly progress of the monitoring process can proceed.

Selection of Drug Therapy 

A pharmacist can make his knowledge of drugs available to the prescriber to ensure that the patient receives the most appropriate drug or dosage form. This can be done either before a drug is selected or after a drug has been prescribed. The pharmacist should be available to the physician to discuss therapeutic alternatives before a drug is selected and prescribed. 

The selection of a drug to achieve a therapeutic goal is a logical process in which a patient’s condition is matched to the drug's characteristics. The characteristics of each drug should be considered regarding side effects, method of administration, cost and potential drug interaction with concurrent therapy, disease states, and diet.

Establishment of Monitoring Parameters 

Pharmacists should establish monitoring parameters to assess the progress toward the therapeutic end-point. A monitoring plan should outline parameters that will be useful in determining whether the therapy is effective and whether the drug is producing any side effects.  

A monitoring plan usually consists of a combination of objective and subjective parameters. 

Objective parameters: Include factors that are measurable by laboratory tests, vital signs, x-ray reports, and blood levels of drugs. 

Subjective parameters: Include factors that are not measurable and require a value judgment such as general appearance or the patient's assessment of his progress. 

An example of parameters useful in monitoring the therapy of patients treated with digitalis glycoside is as follows: 

Objective parameters: Such as digoxin blood level, pulse rate, heart size, and ankle edema. 

Subjective parameters: Would be increased exercise, tolerance, and nausea. 

Pharmacists should monitor these parameters daily and also review the progress notes of the physicians and nurses. Pharmacists should maintain communication with physicians, nurses, and patients to increase the effectiveness of the monitoring process.

Identification and Confirmation of Problems 

A key function in the drug monitoring process is the pharmacist’s identification of existing or potential problems resulting from drug therapy. Pharmacists should use all the information sources for identification and confirmation of problems. The pharmacist should screen and separate patient problems into those which could benefit from drug therapy and those which may be induced by drugs.


When a problem is thought to be related to a drug then research must be conducted concerning the disease state, laboratory data, drug dosage, and other drugs to document the relationship.

Communication of Findings 

When a problem related to drug therapy has been identified, the pharmacist must communicate with the appropriate health professional to initiate action. For a problem involving drug administration, a nurse may be the professional who can best solve the problem. If the problem involves patient intolerance to a drug, the pharmacist should consult with the physician to suggest an alternate drug or dosage formulation. 

Pharmacists should communicate the finding in the “clinical communication form”. This form should be prepared in duplicate in which one copy is sent to the appropriate health professional and the duplicate is kept by the pharmacist to document his activities.

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