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The Overdose Danger

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With drug doses, a one-size-fits-all approach doesn’t work…

When you get a new prescription, the first thing your doctor does (after choosing the drug) is decide on the dose.

What most people don’t think about: Your doctor’s dosing decision is crucial—getting even slightly more of a medication than you need can greatly increase your risk for side effects. Correct dosing, however, can lessen (or even eliminate) side effects.

Each year in the US, drug side effects are estimated to cause more than one million hospitalizations and more than 100,000 deaths. Yet many doctors reflexively prescribe “average” doses without checking recommendations for optimal dosing based on such factors as age, sex and body weight.

For example, a 100-pound woman might be given the same dose as a 200-pound man…and a 75-year-old may be given the same dose as a healthy college student. It’s not hard to guess who is more likely to have preventable side effects. While many people know that taking a blood thinner in a dose that’s too high can have devastating consequences, recent research is focusing on other drugs that can also have dangerous side effects.

Important new finding: With blood pressure drugs and diabetes medication, in particular, excessive doses can increase risk for dizzy spells, confusion, falls and even death—especially among adults age 70 and older, according to recent research in JAMA Internal Medicine.

DOSING DANGERS

Common drugs to watch out for…*

• Blood pressure drugs. About 25% of patients who take one or more of these medications stop using them within six months because of side effects, and up to half quit taking them within a year. The majority of people who take blood pressure drugs will initially suffer from dizziness, unsteadiness, falls or other side effects. Alert your physician if you experience any of these side effects. Even though the discomfort typically wanes over time, it can often be prevented altogether by starting with a lower dose of medication.

Beta-blockers, such as metoprolol (Lopressor) and propranolol (Inderal), are particularly dose-sensitive. So are alpha-blockers, such as prazosin (Minipress). Women who take these drugs tend to have a greater drop in blood pressure/heart rate than men, so they typically need a lower dose. The same may be true of patients who have both high blood pressure and lung disease, who often suffer shortness of breath when they take excessive doses. People who take multiple blood pressure medications are also more likely to have side effects.

My advice: Tell your doctor that you would like to start with one drug. Emphasize that you’d like to take the lowest possible dose—and that you’re willing to be retested (or check your own blood pressure at home with an automated blood pressure monitor) to make sure that the treatment is working.

• Diabetes medications. The risks for diabetes complications—such as nerve damage, blindness, stroke and heart attack—are so great that doctors tend to treat it aggressively. But oral diabetes drugs given in high doses can easily cause blood sugar to fall too low.

Example: Patients who take glyburide (Micronase) or repaglinide (Prandin) often develop hypoglycemia, excessively low blood sugar that can cause dizziness, confusion and other symptoms. Even if the initial dose was correct, physiological changes as you age and/or changes in your lifestyle could make that starting dose too potent. For example, suppose that you start exercising more and eating a healthier diet. You’ll probably need a lower drug dose than you did before, but your doctor might not think (or know) to change the prescription.

My advice: Tell your doctor right away about any lifestyle changes that could affect your blood sugar levels, such as exercise frequency (or intensity), changes in meal timing, etc. Keep careful tabs on your blood sugar with home tests. If your blood sugar is consistently testing at the lower end of the recommended range (or below it), call your doctor and ask whether you should switch to a lower drug dose.

• Painkillers. Aspirin, ibuprofen (Motrin) and other nonsteroidal anti-inflammatory drugs (NSAIDs) are widely available and effective. But they’re also dangerous at high doses. One study found that more than 70% of people who take these drugs daily on a regular basis suffer at least some damage to the small intestine. Like the blood thinner warfarin (Coumadin), they’re a common cause of excessive bleeding.

My advice: Take the lowest possible dose…use painkillers as rarely as possible…and always take them with food. People assume that over-the-counter drugs are safe, but none of these medications are meant to be used long term (more than four weeks).

If you can, switch to one of the many brands of acetaminophen (such as Tylenol). It has about the same pain-relieving effects, but even with its increased risk for liver damage, acetaminophen (taken at the recommended dosage) is less likely than an NSAID to cause side effects.

• Sedatives. Valium and related drugs, known as benzodiazepines, are commonly prescribed sedatives in the US, but the standard doses can be much too high for women as well as older adults.

Medications such as diazepam (Valium), triazolam (Halcion) and zolpidem (Ambien) accumulate in fatty tissue. Since women have a higher percentage of body fat than men, the drug effects can linger, causing next-day drowsiness or a decline in alertness and concentration. In older adults, the drugs are metabolized (broken down) more slowly, causing unacceptably high levels to accumulate in the body.

My advice: Women who are given a prescription for one of these drugs should always ask if the dose is sex-specific. They can ask something like, “Do I need a lower dose because I’m a woman?”

Also, in my opinion, people age 65 or older should avoid these drugs altogether unless they have to take them for a serious problem, such as a seizure disorder. If your doctor says that you need a sedative, ask if you can use a shorter-acting drug such as lorazepam (Ativan)…if you can take it for a short period of time (less than a month)…or if you can get by with a lower dose. Important: These drugs should never be combined with alcohol. The combination increases the sedative effects.

To read more about a drug you’re taking: Go to Drugs.com. 

*Never change a medication dose without consulting your doctor.

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Source: Jack E. Fincham, PhD, RPh, a professor of pharmacy administration at Presbyterian College School of Pharmacy in Clinton, South Carolina. He is also a former panel member of the FDA Nonprescription Drugs Advisory Committee and currently serves on grant review panels for the Canadian Institutes of Health Research Drug Safety and Effectiveness Network. Date: January 1, 2016 Publication: Bottom Line Health
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