Drugs can hurt more than they help

How drugs react with each other sometimes can be a case of the cure being worse than the bite.

The average number of prescription medications taken by older adults is 4.5, plus two non-prescription medicines or supplements, according to a 1996 report by the U.S. General Accounting office. Another study reported 17 percent of hospitalizations of people older than 65 were due to medication reactions — though this is a serious issue affecting people of all ages. Some of the reasons for these admissions were health problems associated with the medicine causing an adverse reaction. Others were due to drug interactions when they were taken with other drugs, supplements and foods.

Before you take that next pill

Medications and supplements are intended to provide the same type of positive results to all who take them, but circumstances can reduce or prevent the effect. Each person is unique, and a percentage of people can take the same drug and dosage yet have very different outcomes. That’s why health-care professionals gather detailed information about a patient and family members’ history with medication.

Sometimes, drugs interact directly. For example, taking a calcium supplement about the same time as thyroid medicine causes the calcium to bind to the thyroid in the gut and interferes with its absorption. The person’s blood thyroid hormone level drops, and hypothyroid symptoms continue, even though the person is taking thyroid medicine. Instead, take thyroid pills on an empty stomach. I suggest to patients they place the pill by their bedside with a glass of water.

Counter-effects

Sometimes, a drug’s effect or side-effect may oppose the intended effect of another drug.
For instance, an anti-inflammatory pain medication like ibuprofen may cause the body to retain salt and water; a diuretic or "water pill" (like furosemide or hydrochlorothiazide) helps the body get rid of salt and water.

If someone has asthma or chronic obstructive lung disease, they may be prescribed an inhaled medicine like albuterol, which helps open up the airways. If this person also has hypertension, certain medications such as beta-blockers (like propranolol) have an opposite effect on the airways and can make breathing more difficult. The addition of the glaucoma medication timolol, which is also a beta-blocker, can worsen breathing in patients who have significant lung disease.

Role of liver and kidneys

Nearly all medicines taken by mouth are absorbed through the intestinal wall and processed through the liver, where blood from the intestine first travels. For some drugs, this creates breakdown products, or metabolites, that also have effects in the body. Other drugs may cause changes in certain proteins that the liver normally makes.

Estrogens taken orally can do this. The liver may generate more blood-clotting proteins, which can increase the chances of stroke, blood clots in the leg veins, and so on. This is one of the reasons why estrogen also has also formulated to be applied topically and absorbed through the skin into the blood vessels, bypassing the effects in the liver.

People who take warfarin (Coumadin) should always monitor their intake of vitamin K-containing foods. The (oversimplified) reason is that warfarin causes the liver to make fewer blood clotting proteins and vitamin K interferes with this action of warfarin in the liver.