Challenges of therapeutic substitution of drugs for economic reasons: focus on CVD prevention.
BACKGROUND
Healthcare systems throughout the world are under increasing pressure to control and minimise costs. The substitution of initially-prescribed drugs with cheaper equivalents is an obvious option which presents a rapid and visible means to reduce these costs. Whether the substitution improves patient and/or population outcomes must be appraised and this paper highlights the conditions under which therapeutic substitution may require additional thought and consideration.


METHODS
In this paper, some of the medical evidence and the regulatory environment for and against the three types of therapeutic substitution - generic, within-class and between-class - are discussed. This article is not an exhaustive review of the literature, but captures some of the key clinical, pharmacological, economic, policy and ethical issues regarding generic and therapeutic substitution. Search criteria of the most commonly used terms, i.e. therapeutic substitution, switching, interchange, and bioequivalence, were applied to Embase, PubMed and Google Scholar to identify relevant publications.


RESULTS
Although population studies support therapeutic substitution in principle, there is evidence that substitution may not always result in therapeutic equivalence in individual patients, with the consequent potential for greater risks of decreased efficacy and/or increased safety concerns. Factors such as patient choice and therapeutic equivalence also play an important role in the effectiveness of the treatment and overall management of the patient. The pan-European regulatory environment provides another contradiction, encouraging widespread cost containment through reduction in drug acquisition costs, while simultaneously promoting an increased role for patients in defining and managing their own treatment.


CONCLUSIONS
There is a strong rationale for careful management in some patients with cardiovascular disease. Treatment decisions should be transparent and based on strong clinical evidence. If not, drug substitution on economic grounds alone cannot be considered to be in the individual patient's interest and is therefore unethical.
Clinical Pharmacology, Barts and The London School of Medicine and Dentistry, London, UK. A.Johnston@qmul.ac.uk
Atholl
A
Johnston
D047228:Angiotensin II Type 1 Receptor Blockers / Q000191:economics* / Q000493:pharmacokinetics / Q000627:therapeutic use; D003363:Cost Control; D003362:Cost-Benefit Analysis; D016568:Drugs, Generic / Q000191:economics* / Q000493:pharmacokinetics / Q000627:therapeutic use; D005060:Europe; D005252:Fees, Pharmaceutical; D017048:Health Care Costs; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D055118:Medication Adherence; D057240:Patient Preference; D013777:Tetrazoles / Q000191:economics* / Q000493:pharmacokinetics / Q000627:therapeutic use; D013810:Therapeutic Equivalency; D006113:United Kingdom; D014481:United States; D014633:Valine / Q000031:analogs & derivatives* / Q000191:economics / Q000493:pharmacokinetics / Q000627:therapeutic use; D000068756:Valsartan
D047228:Angiotensin II Type 1 Receptor Blockers; D016568:Drugs, Generic; D013777:Tetrazoles; D000068756:Valsartan; D014633:Valine