Six surprising drug interactions you should know about

Mixing certain antibiotics and alcohol can leave you feeling nauseous. Credit: metamorworks/Shutterstock

As the UK population grows older, more and more people are using a combination of drugs to treat multiple conditions. This can lead to interactions and side effects that we all need to be aware of. Not only can drugs interact with each other, they can also interact with food and drink, as well as popular herbal remedies.Here are some of the most noteworthy to give you an overview of the combinations to be wary of.

1. Statins and grapefruit juice

17 nov 2018--Many people are prescribed drugs from the statin family to prevent heart attacks and strokes. Statins are the mainstay of cholesterol management but are not free from drug and food interactions. One particularly important interaction to note is that of certain statins with grapefruit juice.
People who have been told that they have high cholesterol often make lifestyle changes, which may involve increasing the amount of fruit and vegetables in their diet. Although this is encouraged, it's important to be aware that grapefruit juice can slow down the breakdown of statins in the body, thereby increasing their presence in the blood, resulting in more side effects.

2. Warfarin and green leafy vegetables

Warfarin, a drug used to prevent and treat blood clots, is commonly prescribed in the UK. People taking warfarin need to go for regular blood tests to make sure that they are taking the right dose to treat their particular condition. An interaction of note with this drug is that with vitamin K.
Supplements and foods that contain vitamin K, such as green leafy vegetables and green tea, can reduce the effect of warfarin by speeding up its removal from the body, meaning that those taking it may suffer serious consequences, including an increased risk of strokes or deep vein thrombosis. You should let your prescriber know if you are making any changes to your diet so that your dose of warfarin can be adjusted accordingly.

3. Antidepressants and ibuprofen

Taking a class of antidepressants called selective serotonin reuptake inhibitors (SSRIs), such as citalopram, alongside anti-inflammatory painkillers, such as ibuprofen, can increase the risk of internal bleeding. This is usually associated with the stomach and symptoms can include dark stools, stomach cramps, feeling tired, blood in vomit and feeling faint or dizzy.
This side effect can be avoided by taking a stomach protecting drug, such as lansoprazole. It's important to note, however, that certain other stomach protecting drugs may also interact with antidepressants, so it's important to choose wisely.

4. Metronidazole and alcohol

Metronidazole is a commonly prescribed antibiotic, particularly for dental infections. Although your pharmacist may often encourage you not to drink alcohol while taking prescribed medication, this advice is particularly important with metronidazole.
Drinking alcohol while on metronidazole can lead to severe nausea and vomiting. Not only should you avoid alcohol while taking metronidazole, you should wait for at least two days after your course has finished. This is to make sure that all of the drug has left your body.

5. St John's Wort and the contraceptive pill

St John's Wort is a popular herbal remedy, used to treat the symptoms of mild depression. Some people assume that because it is a herbal remedy, it must be harmless. Quite the opposite.
St John's Wort is an example of an enzyme inducer, a substance that speeds up the breakdown of another substance. By encouraging the breakdown of the other drug at a faster rate than normal, this means that the other drug becomes less effective.
While St John's Wort can have this effect on many drugs, one of particular note is the contraceptive pill. St John's Wort decreases the effectiveness of the pill, increasing the chance that the person taking the pill will become pregnant.
The interaction is so severe that the UK's Medicines and Healthcare products Regulatory Agency has advised that the combination of St John's Wort and the combined hormonal contraceptive pillshould be avoided altogether.

6. Calcium supplements and other medications

As we get older, our bones become weaker, so many people are prescribed calcium and vitamin D supplements to strengthen their bones and prevent fractures. While these products benefit many, it is important to understand that they may affect how the body absorbs other drugs. These include drugs to prevent malaria, certain antibiotics and those used to treat an underactive thyroid.
For most drugs, this interaction can be overcome by leaving time between taking the calcium product and the other drug. A gap of between two and six hours between taking calcium and other drugs is usually enough.
It is very important that if you are taking any of the drugs mentioned in this article that you do not stop taking any of them until you have consulted with your doctor. Any sudden changes to medication may have more severe consequences than any of the interactions listed in this article.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Provided by The Conversation

Lack of communication puts older adults at risk of clashes between their medicines

Key results from the National Poll on Healthy Aging. 

Most older Americans take multiple medicines every day. But a new poll suggests they don't get - or seek - enough help to make sure those medicines actually mix safely.
That lack of communication could be putting older adults at risk of health problems from interactions between their drugs, and between their prescription drugs and other substances such as over-the-counter medicines, supplements, food and alcohol.

03 dec 2017--The new results, from the National Poll on Healthy Aging, show that only about one in three older Americans who take at least one prescription drug have talked to anyone about possible drug interactions in the past two years.
Even among those taking six or more different medicines, only 44 percent had talked to someone about possible drug interactions.
The results come from a nationally representative sample of 1,690 Americans between the ages of 50 and 80. The poll was conducted by the University of Michigan Institute for Healthcare Policy and Innovation, and sponsored by AARP and Michigan Medicine, U-M's academic medical center.

Disjointed sources of care

Part of the reason for lack of communication about drug interactions may lie in how older Americans get their health care and their medicines. One in five poll respondents said they have used more than one pharmacy in the past two years, including both retail and mail-order pharmacies. Three in five see multiple doctors for their care.
And even though 63 percent said their doctor and pharmacist are equally responsible for spotting and talking about possible drug interactions, only 36 percent said their pharmacist definitely knew about all the medications they're taking when they fill a prescription.
"Interactions between drugs, and other substances, can put older people at a real risk of everything from low blood sugar to kidney damage and accidents caused by sleepiness," says Preeti Malani, M.D., the director of the poll and a professor of internal medicine at the U-M Medical School.
"At the very least, a drug interaction could keep their medicine from absorbing properly," she adds. "It's important for anyone who takes medications to talk with a health care professional about these possibilities."
Malani notes that although 90 percent of poll respondents said they were confident that they knew how to avoid drug interactions, only 21 percent were very confident.
Given the wide range of prescription and over-the-counter drugs on the market, and the number of drugs that interact with supplements, alcohol and certain foods, Malani says it's hard for even medical professionals to catch all potential interactions.
Newer medical computer systems that flag patients' records for potential interactions automatically, based on the names of their drugs, are helping, Malani says.
Also helpful is Medicare coverage for prescription drug reviews, called Medication Therapy Management, for people who take medicines for multiple chronic conditions. But not all medical computer systems talk to one another, and an MTM must be approved by the patient's Medicare prescription drug benefit provider.
"Even with trackers and systems in place, patients need to be open with their providers and tell them all the medications and supplements they're taking, including herbal remedies," says Alison Bryant, Ph.D., senior vice president of research for AARP. "It's especially important for older adults to be vigilant about this because they tend to take multiple medications."
AARP has put together a free online drug interaction tracker that can identify potential risks. It's available at http://healthtools.aarp.org/drug-interactions, but should be used in conjunction with a patient's conversations with their health care providers and pharmacists.

Recommendations for patients and providers

Malani and her colleagues say that it is up to patients, pharmacists and doctors alike to reduce drug interaction risks.
Patents should write down the names and dosages of their prescription medicines, and of any supplements and over-the-counter drugs they take, and bring it all to their doctors' appointments or pharmacies, she says. It is also important to be truthful about alcohol consumption when asked, since alcohol use can affect many medications. And patients shouldn't just stop taking a medicine if they think they're experiencing a side effect - they should also call their doctor's office or speak with a pharmacist first.
Meanwhile, health care providers should ask patients more about what medicines and supplements they take, and counsel patients at risk of side effects using language they can understand.
The poll results are based on answers from those who said they took at least one prescription drug, among a nationally representative sample of about 2,000 people ages 50 to 80. The poll respondents answered a wide range of questions online. Questions were written, and data interpreted and compiled, by the IHPI team. Laptops and Internet access were provided to poll respondents who did not already have it.


Provided by University of Michigan

Older people mixing drugs: study

CHICAGO, 25 dec 2008 – Potentially dangerous mixing of medications is common among older people and non-prescription drugs are the culprit more than half of the time, a new study has found.

US researchers found nearly one out of every 25 people aged 57 to 85 took dangerous combinations of drugs with the potential for serious interactions, the study found.

For men ages 75 to 85, it was as high as 1 in 10.

"The public has an awareness that two prescription medications used together might be dangerous," said study author Stacy Tessler Lindau of the University of Chicago Medical Center.

"But what people don't fully appreciate is that non-prescription drugs can interact with prescription drugs and even other non-prescription drugs."

About a third of older adults uses five or more prescriptions and about half use over the counter medications and dietary supplements, the study found.

More than half of older adults used five or more prescription medications, over-the-counter medications or dietary supplements while 29 percent took more than five prescription medications.

More than half of the dangerous drug combinations included the use of aspirin or blood thinners such as warfarin.

The most common dangerous combination of non-prescription drugs was ginkgo biloba and aspirin which can increase the risk of internal bleeding when taken together.

Researchers at the University of Chicago studied the medication use of 3,500 people aged 57 to 85 living independently across the United States to create a representative sample.

When extrapolated to the general population, the study found that some 2.2 million people were at risk from dangerous combinations of medications.

A recent report found that US adults over the age of 65 make are taken to the emergency room more than 175,000 times every year because of bad reactions to medication.

The study was published in this week's edition of the Journal of the American Medical Association.

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The ‘Poisonous Cocktail’ of Multiple Drugs

By JANE E. BRODY
A 78-year-old woman was found unconscious on the floor of her apartment by a neighbor who checked on her. The woman could not remember falling but told doctors that before going to bed she had abdominal pain and nausea and had produced a black stool, after which she had palpitations and felt lightheaded.
Her medical history included high blood pressure, coronary artery disease, atrial fibrillation, congestive heart failure and osteoarthritis. She also had a cold with a productive cough. For each condition, she had been prescribed a different drug, and she was taking a few over-the-counter remedies on her own. These were the medications:
¶Lopressor to control high blood pressure.
¶Digitalis to help the heart pump and control its rhythm.
¶Coumadin to prevent a stroke caused by blood clots.
¶Furosemide, a potent diuretic to lower blood pressure.
¶Lipitor to lower serum cholesterol.
¶Baby aspirin to reduce cardiac risk from blood clots.
¶Celebrex for arthritis pain.
¶Paxil for depression and anxiety.
¶Valium, as needed, to help her sleep.
¶Levofloxacin, an antibiotic for the cough.
¶Ibuprofen for body aches.
¶Cough medicine.
This is what doctors call polypharmacy, otherwise known as a “poisonous cocktail” of many drugs that can interact in dangerous ways and cause side effects that can be far worse than the diseases they are treating. Elderly people are especially vulnerable because they often have several medical problems for which they see different doctors, each prescribing drugs, often without knowing what else the patient is taking.
The woman described above passed out because she had a bleeding stomach ulcer from a combination of drugs that irritate the stomach, Celebrex, ibuprofen and aspirin, and thin the blood, coumadin and aspirin, made worse by an antibiotic that raises blood levels of coumadin.
She recovered after a transfusion of two units of packed red blood cells and was sent home with strict instructions to stop the Celebrex, ibuprofen and aspirin and advice to “contact her internist and psychiatrist regarding possible medication changes that might decrease the risk for future adverse events,” Dr. Michael Stern reported in the June issue of Emergency Medicine.
Dr. Stern, a specialist in geriatric emergency medicine at New York Presbyterian Hospital/Weill Cornell Medical Center, noted that the elderly took about 40 percent of prescribed drugs, roughly twice what younger adults take, and that they suffered twice as many adverse drug reactions as younger people.
“The average community-dwelling older adult takes 4.5 prescription drugs and 2.1 over-the-counter medications,” Dr. Stern reported. Polypharmacy is responsible for up to 28 percent of hospital admissions and, he added, if it were classified as such, it would be the fifth leading cause of death in the United States.
The Effects of Aging
Various drugs taken by the elderly can interact dangerously. Some drugs use the same metabolic pathway and, thus, compete with one another, which can result in hazardous blood levels of one or more drugs. Some drugs cause effects like dehydration that reduce kidney function and the ability to eliminate drug metabolites. The combined effects of some drugs can be more potent than the prescriber intended.
In addition to seeing several doctors, many older people use multiple pharmacies to buy prescriptions. There may be no single health professional who knows what they are taking and could alert them to dangerous combinations. This is especially true in places where chain stores have replaced independent pharmacies or when the patient’s drug plan requires that medications be ordered by mail.
It is not just the number of diseases, drugs or doctors that is the problem. Age-related changes in physiology can worsen matters significantly, even if just two or three drugs are being taken. Just as a child is not the same as a small adult, pharmacologically speaking, an elderly person is not just an older young adult.
Major organ systems function less efficiently in older people. The heart’s ability to pump blood declines with age, as does absorption by the gut, the breakdown of drugs by the liver and the ability of the kidneys to excrete them. With aging, the percentage of lean body mass declines, and body fat increases. Thus, aging affects how much of a drug reaches the bloodstream, how well it is distributed in the body and how effectively it is cleared from the system.
Drugs like digitalis and coumadin, which are primarily distributed in lean tissues, are likely to reach higher blood levels in people older than 65. So the prescribed dosages should be lowered to reduce the risk of toxic side effects. Other drugs, like Valium and barbiturates, that are distributed in fatty tissue can accumulate in the elderly body and remain active longer, increasing side effects like sedation.
Aging also results in fewer protein binding sites for drugs, resulting in a higher blood level of the drug that loses the competition for sites.
Furthermore, aging can affect the responses to certain medications. This is especially true for those that influence blood pressure and the brain. Drugs like Valium, antidepressants and antihistamines can cause effects like delirium, agitation, sleepiness, depression and worsening dementia in older people, Dr. Stern wrote.
Preventing Problems
Keep a list of all medications you take and their dosages and dosing schedules. This should include prescription drugs, over-the-counter and herbal remedies and vitamin and mineral supplements. Take the list whenever you go to the doctor, and make sure that the doctor reviews it before prescribing something else. In addition, because doctors are not always familiar with the actions of all drugs, take the list to the pharmacy when ordering a new prescription and ask the pharmacist to review it for potential interactions.
It also helps to order all medications from the same pharmacy, which should keep a computerized record of everything you take. That way, a possible hazard will not be missed if different pharmacists are on duty.
Never take an over-the-counter or herbal remedy without checking with your doctor. If your doctor is hard to reach or ill informed, ask the pharmacist whether the remedy is safe in view of the other drugs you take.
Carefully review and abide by all dosing directions, especially those that say, “Take with food,” “Take one hour before meals,” “Do not consume alcohol while on this drug,” or, “Do not take this medicine if you are also taking ...”
Ask the prescribing doctor what side effects to expect and what should prompt an immediate call to the doctor. Do not assume that a decline in well-being is caused by a disease or age. It could be a drug side effect.

Drug Prescribing for Elderly Called in Calamitous State

BRUSSELS, Belgium, July 13 -- Drug prescribing for elderly patients is missing even a semblance of evidence-based guidance, constituting a worldwide public-health problem, said international researchers.
A pair of reports meta-analyses, conducted by the same team and reported in the July 14 issue of The Lancet noted the many holes in the logic used for drug prescribing for elderly patients and cited inadequate physician training in geriatric pharmacotherapy.
In an effort to sort out the complexities of prescribing for these often frail or disabled patients, Anne Spinewine, Ph.D., of Université catholique de Louvain here, and U.S. and British colleagues, examined recent randomized intervention studies aiming to offer strategies for prescribing for elderly people. Separately, they evaluated ways to manage drug interactions.
Appropriate prescribing, they said, should aim to promote the use of evidence-based therapies and keep the use of drugs for which there is no clinical need or where there is dubious efficacy to a minimum.
In the first study, dealing with appropriate prescribing, the investigators searched Medline (1970-2006), International Pharmaceutical Abstracts (1970-2006), the Cochrane Database, and additional studies, to identify, for example, appropriate or inappropriate prescribing, patient outcomes, and adverse drug reactions among patients 65 and older.
They pointed out that several factors specific to frail elderly patients, such as the use of benzodiazepines, increase the complexity of prescribing. Furthermore, clinical evidence for the effect of drugs on elderly people is scarce, goals of treatment might change, and social and economic factors might be unique to older patients.
The investigators found that aside from faulty memory and confusion, the patients themselves can influence prescribing decisions on the basis of their expectations. Contributing to the problem is physicians' inadequate training in geriatric pharmacotherapy.
They found the evidence mixed and contradictory for a link between inappropriate prescribing and adverse patient outcomes. No clear conclusions can be made about the predictive validity of specific measures, they found, except for criteria for the underuse of drugs for cardiovascular disease. They called for studies that test the predictive validity of measures of inappropriate prescribing for elderly people.
Evidence suggests that a patient's decision to take or not to take drugs might be part of a negotiation process rather than a final stance, the researchers found,, and changing patients' behavior is more likely if patients are helped to make decisions for themselves rather than being told what to do.
In the second study, including Dr. Spinewine as a co-author with a similar meta-analysis, the researchers took on the challenge of managing drug interactions in these patients, suggesting strategies for assisting in their detection, management, and prevention.
Elderly patients are at high risk of drug interactions yet the prevalence of these interactions is not well documented, they wrote. Patients frequently take many drugs, have several co-morbidities, and might not maintain adequate nutritional status.
Several types of interactions exist, they pointed out, such as drug-drug, drug-disease, drug-food, drug-alcohol, drug-herbal products, and drug-nutritional status.
Factors such as age-related changes in pharmacokinetics and pharmacodynamics, frailty, interindividual variability, reduced homeostatic mechanisms, and psychosocial issues need to be considered when drug interactions are assessed, they said.
Software can help clinicians detect drug interactions, but many programs have not been updated with the evolving knowledge of these interactions, and do not take into consideration important factors needed to optimize drug treatment in elderly patients.
Any generated recommendations have to be tempered by a holistic, geriatric, multiprofessional approach that is team-based.
Discussing the frequency pf drug interactions, the researchers noted that in a European study of 1,601 outpatients, 46% had at least one potential clinically significant drug-drug interaction, with 10% of these interactions regarded as of high severity.
Offering a simple clinical approach to managing drug interactions, the researchers listed several categories. The first category includes drug-drug interactions for drugs with a narrow therapeutic index, such a digoxin, phenytoin, or warfarin. These interactions are generally well known, have laboratory monitoring tests, and are detected by all commercial software systems.
The second category involves complex interactions, which includes patients with nine or more drugs and five or more comorbidites. Although the choice of an individual drug is usually appropriate, when considered individually, the combination can yield unwanted results.
The third category, involves cascade interactions, in which an adverse drug interaction is misinterpreted as a new medical disorder and another drug is prescribed, adding to the risk generated by a potentially unnecessary treatment.
In advice to clinicians, the researchers suggested that astute clinicians can screen any specific situation to detect drug interactions, frequently by asking the right questions.
Results suggest that elderly patients usually do better when their care is managed by a multidisciplinary geriatric team, consisting of a physician (geriatrician), nurse, and pharmacist with communication between these professionals, the investigators said.
No financial conflicts were reported by the researchers for either study. Financial support for both studies was provided by the Belgian Fonds National de la Recherche Scientifique (at the time of writing, Dr. Spinewine was a research fellow of this organization). Further support for the first study was provided by the National Institute of Health, the Agency for Health Care Quality, the Commonwealth Fund, and the Retirement Research Foundation and Research and Development Office, Northern Ireland. Primary source: The LancetSource reference: Spinewine A, et al "Prescribing in Elderly People 1: Appropriate prescribing in elderly people: how well can it be measured and optimized?"The Lancet 2007; 370: 173-184. Additional source: The LancetSource reference: Mallet L, et al "Prescribing in Elderly People 2: The challenge of managing drug interactions in elderly people" The Lancet 2007; 370: 185-191.

Cancer patients are at high risk for potential drug interactions

Potential drug interactions from prescribed medications are common among cancer patients and may cause unnecessary harm, according to a study in the April 18 Journal of the National Cancer Institute.
Cancer patients often take several medications at the same time, not only for treating their cancer but also for side effects and other secondary illnesses. Because of this, they can be at high risk for adverse drug interactions and duplicate medications. Consequences of these interactions can range from inactivation of cancer-fighting medications to severely injuring or killing the patient.
Rachel Riechelmann, M.D., of the Princess Margaret Hospital in Toronto, and colleagues gave 405 cancer patients a questionnaire about the medications they had taken in the last four weeks. Their responses were analyzed using a drug interaction software program that could identify potential interactions and rank them by severity.
Nearly a third of patients were exposed to at least one potential drug interaction. The researchers identified 276 drug combinations with the potential to interact. About nine percent of the interactions considered of major severity—risk of death—and 77 percent of moderate severity—risk of serious health problems. About eight percent of the patients received duplicate medications.