Rational use of Metoprolol: The Relationship of Its Blood Concentration to Patient Compliance, Poor Quality Medicines and Side Effects
Keywords:
Metoprolol, Plasma concentrations, Adverse effects, Brand products, Proper useAbstract
Background: Patients with cardiovascular diseases might be poorly educated regarding the rational use of their drug treatment, such as dealing with missing doses, relationship to food, and potential side effects. In addition, many poor quality medications are available in our drug market that might differ in their efficacy and safety profiles.
Aim: Metoprolol, a commonly used drug in our local medical practice, is to be investigated through measuring its blood concentration at one point of time after achieving the steady state, and to correlate blood concentration with compliance, side effects and the quality of brand products they are using.
Methods: Measurement of levels of metoprolol (by scanning spectrometry) in blood samples taken from patients at their visits to the consultation clinics in Thi-Qar during the period October 2014 to April 2015 was made. Their blood concentrations was correlated with compliance, side effects and the quality of the drugs they were using. A questionnaire containing patient demographic information, type disease, type of drugs, trade names, and a check-list of potential side effects, was used.
Results: Out of the 56 patients who were treated with different preparations and dosage regimens of metoprolol, 53 patients were within the reported therapeutic range of metoprolol plasma concentration (0.035-0.5µg/ml). The two brand metoprolol products used were found interchangeable with no significant difference in their achieved plasma concentration. The most frequent adverse effects associated with the use of metoprolol were tiredness followed by dyspnea and bradycardia. There is no difference between the two brand products of metoprolol in relation to the frequency of side effects. Around 90% of patients using metoprolol were not aware of the proper action to be taken when they miss a dose. 23.2% of patients who reported missing one or more doses did not take any action till the next dose.
Conclusion: Availability of more than one brand product of metoprolol and other drugs need to be investigated in terms of their blood levels and occurrence of adverse effects especially when these drugs are used for long duration to test their interchangeability. Patient awareness of the proper use of drugs is necessary in order to increase effectiveness of their treatment and decrease potential side effects.
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