Michael L. Tan had written an article entitled "Generics again."* Although it was written last year, I have read it only last September. Nevertheless, I still sent the editor my feedback on the article.
Here's my feedback:
Dear Sir,
While it is true that the Generics Act of 1988 requires that consumers be informed of the choices available to them in the selection of drugs with the same active ingredient (generic name of the drug), there are cases when the dispensing pharmacist should be cautious in doing so for reasons that may have undesirable effects to the patient.
This is because, based on bioequivalence studies, there are certain drugs made by different manufacturers that do not produce the same blood levels (bioavailability) and subsequent effects to the patient.
For example, here in the Philippines, Appendix T of the latest edition of the Philippine National Drug Formulary (vol. 1 6th ed., 2005) contains a list of "Drugs Requiring Stict Precaution in Prescribing, Dispensing and Use Because of Bioavailability Problem and Availability in Philippine Market in Several Brands/Manufacturers; Prescription Must be Filled According to the Specified International Non-proprietary Name (INN) and Brand Name (B)."
I would say that if a patient was already started with a certain brand of drug that is included in the list, it is safer to stick to that brand than to obtain varying levels and effects because of switching from one brand to another brand. It may be helpful also to consult first the prescriber before attempting to change brands.
Of course, an informed consumer can start with a cheaper and still effective drug if pharmacists provide the information required of them under the law.
Two of the drugs you mentioned in your aritcle (atenolol and propranolol) are included in Appendix T of the PNDF and better control of hypertension may be achieved if only one brand of those drugs is to be taken as maintenance therapy.
Also, R.J. Taylor (a pyschiatrist), in writing to the Australian Prescriber (vol. 28 no. 4, Aug. 2005)**, said that "we should remember that we are NOT just prescribing the active ingredient when we prescribe. There is the issue of varying particle size and varying excipients that may make a difference." As an example, he mentioned that "I once had a pyschotic patient with lactose intolerance and I had to work to identify which brands (or even which strengths of the same brand) of antipyschotics were lactose free." (Lactose is used as a base in some prescription drugs and over-the-counter medications.)
Indeed, there are excipients (and other pharmaceutical ingredients) added to the active component (the drug itself) to produce a drug product (i.e., drug + excipients) that sometimes make the difference. Some of these excipients may produce allergic reactions to susceptible patients which explain why some patients are "hiyang" to certain brands of drugs having the same active ingredient.
I am also in support of the Generics Act but these are two of the exemptions which I think should be remembered in choosing cheaper generic drugs over certain expensive branded drugs."
pinoypharmacist's note: I have limited knowledge in pharmacokinetics and biopharmaceutics. If there is anything that is not correct regarding my understanding of the subjects, kindly inform me. It shall be greatly appreciated.
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