Consumption and costs of antihypertensive drugs in Mexico: are diuretic agents a standing technological trajectory?

BACKGROUND

Little is known about hypertension medication consumption and costs in Mexico. Hypertension control is a pharmacological challenge and a public health issue.

OBJECTIVE

(a) To compare drug sales, number of written prescriptions, and monthly treatment costs among 5 classes of antihypertensive drugs and (b) to analyze diuretic drug sales and prescriptions to determine whether these antihypertensive agents represent an established technological trajectory.

METHODS

A retrospective time series data study from 1999 to 2003. Data sources used were International Marketing Services of Mexico drug sales and the Mexico Prescription Audit databases. The 5 different classes of antihypertensive drugs were accommodated into 4 main technological trajectories according to their main biological mechanisms of action. Each technological trajectory was assessed using consumption and prescription data. Daily defined dose was used to calculate drug treatment costs.

RESULTS

The market for cardiovascular agents is one of the largest, and in 2003 accounted for a value market share of 59 billion US dollar and a unit share of 40.7 million. Among cardiovascular agents, antihypertensive drugs made up a large percentage of market shares. Calcium channel blockers and angiotensin-converting enzyme inhibitors I had the biggest share value of the total cardiovascular market. Amlodipine had the highest share among calcium channel blockers, and enalapril and captopril had the largest share among angiotensin-converting enzyme inhibitors I. The top-selling diuretic drug was furosemide. The trend in number of prescriptions was parallel to that in sales. The diuretic spironolactone was the most expensive drug treatment (59 US dollar). Treatment with spironolactone might represent 47% of the income of a Mexican family if their household income was close to minimum wage (124 US dollar).

CONCLUSIONS

The most effective and least expensive drugs-diuretics-had the smallest market share of all antihypertensive agents in Mexico. Nevertheless, diuretic agents are still in use and kept over time a steady market share both in value and in units.