How many pill bottles are in your medicine cabinet?

According to Mayo Clinic Researchers, prescription medications may be more common that you think. This is according to a new report from the Mayo Clinic of Rochester titled "Age and Sex Patterns of Drug Prescribing in a Defined American Population,' which says nearly 70% of Americans are now taking at least one prescription drug.

The use of prescription drugs has steadily increased over the last decade. In 1999 only 44% of adults were taking prescription medications. By 2009:

• 17% of patients were taking antibiotics
• 13% taking antidepressants
• 13% taking opioids
• 11% are on blood pressure medications
• 11% are receiving vaccines

The cost of these prescriptions reached $250 billion in 2009 and accounted for 12% of total personal health care expenditures. Drug-related spending is only expected to increase.

Women and older adults seemed to have a higher prevalence of prescription drug use. Among teenagers and younger patients, vaccines, antibiotics, and anti-asthma drugs were most common. As the population aged, antidepressants and opioids became more common, as did cardiovascular drugs.

The high prevalence of antidepressants and opioids can be concerning. Opioids are powerful painkillers that can have strong addictive effects and are sometimes found as illicit street drugs. Furthermore, opioids and many antidepressants rely on the highly polymorphic CYP2D6 metabolic pathway and both classes of drugs can have major adverse effects.

Polypharmacy, the taking of multiple drugs concomitantly, was also shown to be a growing condition. Over 20% of patients were taking five or more prescription medications at the same time. Polypharmacy is a strong indicator of drug-drug interactions and probable adverse effects. As the number of medications a patient takes rises, so too does the risk of complications.

Researchers believe their study population is representative of the US population as a whole.