Fitness and Exercise

Most of the time, medicines  make our lives better. They reduce aches and pains, fight infections,  and control problems such as high blood pressure or diabetes. But  medicines can also cause unwanted reactions.

One problem is interactions, which may occur between

• Two drugs, such as aspirin and blood thinners
• Drugs and food, such as statins and grapefruit
• Drugs and supplements, such as ginkgo and blood thinners
• Drugs and diseases, such as aspirin and peptic ulcers

Interactions can change the actions of one or both drugs.   The drugs might not work, or you could get side effects.

Side effects are unwanted effects caused by the drugs.  Most are  mild, such as a stomach aches or drowsiness, and go away after you stop  taking the drug.  Others can be more serious.

Drug allergies are another type of reaction.  They can be mild or  life-threatening.  Skin reactions, such as hives and rashes, are the  most common type. Anaphylaxis, a serious allergic reaction, is more rare.

When you start a new prescription or over-the-counter medication, make sure you understand how to take it correctly.  Know which other medications and foods you need to avoid. Ask your health care provider or pharmacist if you have questions. 

MedlinePlus-Dietary Supplements

MedlinePlus-Antioxidants

MedlinePlus-Vitamins

• Among  all fruit juices, grape fruit juice (GFJ) possesses high interaction  with almost all types of drugs. The juice modifies the body’s way of  metabolizing the medication, affecting the liver’s ability to work the  drug through a person’s system. Taniguchi in 2007 reported a case of  purpura (blood spots, pooling of blood underneath the skin) associated  with the ingestion of cilostazol, aspirin and grapefruit juice in 79  years old man. His purpura disappeared upon cessation of grapefruit  juice, although his medication was not altered. The most probable cause  of his purpura is an increase in the blood level of cilostazol because  of the inhibition of cilostazol metabolism by components of grapefruit  juice; Taniguch.
• Numerous  reports have documented drug interactions with GFJ that occur via  inhibition of CYP3A enzymes. Furanocoumarins present in GFJ inhibit the  intestinal CYP 3A4 and have been shown to increase the oral  bioavailability of medications that are CYP 3A4 substrates like  Felodipine, midazolam, cyclosporine and raise their concentrations above  toxic levels.
• GFJ  is generally contraindicated to patients taking psychotropics and it is  advised to inform patients about described interaction. The in vitro  data suggest that compounds present in grapefruit juice are able to  inhibit the P-gp activity modifying the disposition of drugs that are  P-gp substrates such as talinolol. The overall exposure of some drugs  can be increased by more than fivefold when taken with GFJ and increase  the risk of adverse effects.
• With  new anticonvulsants, serum iron and sodium need to be monitored.  Additionally, users are advised to avoid drinking grape fruit juice  within 1-2 hr(s) of taking these anticonvulsants. Furanocoumarines and  active bioflavonoids present in GFJ are also inhibitors of OATP and when  ingested concomitantly, can reduce the oral bioavailability of the OATP  substrate, fexofenadine. Overall, a series of flavonoids present in GFJ  are identified as esterase inhibitors, of which kaempferol and  naringenin are shown to mediate pharmacokinetic drug interaction with  most of the calcium channel antagonist and the statin groups of drugs  such as enalapril and lovastatin due to their capability of esterase  inhibition.
• Cholesterol-lowering  agent lovastatin should be taken with food to enhance gastrointestinal  absorption and bioavailability. The absorption of rosuvastatin, another  anti-hyper lipidemic agent, was significantly decreased in the fed state  compared with the fasting state, which suggests that rosuvastatin  should be administered on an empty stomach.
• Simvastatin,  Ezetimibe, pravastatin and fluvastatin may be taken without regards to  food. However, high fiber diets may lower the efficacy of these drugs.  Concomitant administration of statins with food may alter statin  pharmacokinetics or pharmacodynamics, increasing the risk of adverse  reactions such as myopathy or rhabdomyolysis or reducing their  pharmacological action. Consumption of pectin or oat bran together with  Lovastatin reduces absorption of the drug, while alcohol intake does not  appear to affect the efficacy and safety of Fluvastatin treatment.

MedlinePlus-Blood Thinners

• Warfarin  is commonly used to treat or prevent thromboembolic events. Patients  taking warfarin are at particular risk of interactions with dietary  supplements, yet approximately 30% use herbal or natural product  supplements on a regular basis. There is a possible interaction between  warfarin and a high-protein diet. The potential for increased dietary  protein intake to raise serum albumin levels and/or cytochrome P450  activity has been postulated as mechanisms for the resulting decrease in  international normalized ratio (INRs).
• Some  vegetables (broccoli, Brussels sprouts, kale, parsley, spinach, and  others) are high in vitamin K. Eating large quantities or making sudden  changes in the amounts eaten of these vegetables, interferes with the  effectiveness and safety of warfarin therapy.
• Eating  charbroiled food may decrease warfarin activity, while eating cooked  onions may increase warfarin activity. Soy foods have been reported both  to increase and to decrease warfarin activity. The significance of  these last three interactions remains unclear. The combination of  warfarin administration and cranberry juice ingestion appeared to be  associated with an elevated INR without bleeding in elderly patient.
• A  number of studies have been documented on the interaction of warfarin  and cranberry juice. Cranberry juice is a flavonoid, which has been  shown to induce, inhibit, or act as a substrate for the biosynthesis of  several cytochrome P-450 (CYP) isoenzymes. Specifically, cranberry juice  may inhibit the activity of CYP2C9, the primary isoenzyme involved in  the metabolism of S-warfarin. It was suggested that cranberry juice  increased the International Normalized Ratio (INR) of patients taking  warfarin, but neither clearly identified cranberry juice as the sole  cause of INR elevation. If warfarin sodium is ingested with leafy green  vegetables, the hypoprothrombinemic effect of warfarin may be decreased  and thromboembolic complications may develop.

MedlinePlus-Antidepressants

• Antidepressant  activity of monoamine oxidase inhibitors (MAOIs) was initially noted in  the 1950s. Although older monoamine oxidase inhibitors (MAOIs) are  effective in the treatment of depressive disorders, they are  under-utilized in clinical practice due to main concerns about  interaction with tyramine-containing food (matured cheese, red vine,  ripped bananas, yogurt, shrimp paste and salami) or so called cheese  reaction, since they are capable of producing hypertensive crisis in  patients taking MAOIs.
• The  first-generation MAOIs such as phenelzine and isocarboxazid were  largely nonselective inhibitors of both subtypes of MAO, MAO (A) and MAO  (B). These medications carried with them dietary restrictions. Tyramine  is an indirectly acting sympathomimetic agent, is degraded by MAO but  in the presence of MAOIs, it escapes degradation and reaches the  systemic circulation where it is taken up by the adrenergic neuron,  leading to a hypertensive crisis. However, MAOIs have been well  established as an effective intervention for people with  treatment-resistant depression, and transdermal formulations may provide  a valuable therapeutic option and eliminate the drug-food interaction.

MedlinePlus-Antibiotics

• Antibiotics  are widely prescribed in medical practice. Many of them induce or are  subject to interactions that may diminish their anti-infectious  efficiency or elicit toxic effects. Food intake can influence the  effectiveness of an antibiotic.  Avoid co-administration of antibiotics  with milk products which are rich sources of divalent ions, such as  calcium and magnesium that complex with some antibiotics and prevent  their absorption. The intake of dairy products, however, needs to be  monitored and encouraged with appropriate consideration of specific  antibiotics involved.
• A  number of studies give evidence that fluoroquinolones forming slightly  soluble complex with metal ions of food show reduced bioavailability.  Casein and calcium present in milk decrease the absorption of  ciprofloxacin. The effect of interaction of five fruit juices on the  dissolution and absorption profiles of ciprofloxacin tablets were  determined. It was found that the absorption of ciprofloxacin (500 mg)  tablets can be reduced by concomitant ingestion of the GFJ. Therefore,  to avoid drug therapeutic failures and subsequent bacterial resistance  as a result of sub-therapeutic level of the drug in the systemic  circulation, ingestion of the juice with ciprofloxacin should be  discouraged. Azithromycin absorption is decreased when taken with food,  resulting in a 43% reduction in bioavailability. Tetracycline should be  taken one hour before or two hours after meals, and not taken with milk  because it binds calcium and iron, forming insoluble chelates, and  influencing its bioavailability. The effect of milk added to coffee or  black tea on the bioavailability of tetracycline was evaluated in  healthy individuals. Results showed that even a little quantity of milk  containing extremely small amounts of calcium severely impair the  absorption of the drug, so that the presence of this metal ion should be  carefully controlled in order to avoid decreasing the available  tetracycline.
• Food-drug  interactions may reduce the bioavailability of drugs taken after meals  (negative food effects). However, enteric-coated tablets that start to  disintegrate when they reach the middle-to-lower region of the small  intestine could reduce negative food effects. Results indicated that  food-drug interactions were avoided by separating the main absorption  site of drugs from that of food components.

MedlinePlus-Pain Relievers

• Analgesics  and antipyretics are used to treat mild to moderate pain and fever. For  rapid relief, acetaminophen should be taken in an empty stomach because  food may slow the body absorption of acetaminophen. Co-administration  of acetaminophen with pectin delays its absorption and onset. NSAIDs  like ibuprofen, naproxen, ketoprofen and others can cause stomach  irritation and thus they should be taken with food or milk. Avoid or  limit the use of alcohol because chronic alcohol use can increase the  risk of liver damage or stomach bleeding. The absorption of ibuprofen  and oxycodone when given in the combination tablet was affected by the  concomitant ingestion of food.
• The  Cmax and AUC0-alpha of ibuprofen were significantly increased after  single and multiple doses of Coca-Cola, thereby indicating increased  extent of absorption of ibuprofen. The daily dosage and frequency of  ibuprofen must be reduced when administered with Coca-Cola. Food intake  did not appear to affect the extent of absorption (ie, total exposure)  of oral Diclofenac potassium soft gelatin capsule at doses.

MedlinePlus-Steroids

• Bronchodilators  like theophylline, albuterol, and epinephrine possess different effects  with food. The effect of food on theophylline medications can vary  widely. High-fat meals may increase the amount of theophylline in the  body, while high-carbohydrate meals may decrease it. Avoid alcohol if  taking theophylline medications because it can increase the risk of side  effects such as nausea, vomiting, headache and irritability. Avoid  eating or drinking large amounts of foods and beverages that contain  caffeine (e.g., chocolate, colas, coffee, and tea) since theophylline is  a xanthine derivative and these substances also contain xanthine. Hence  consuming large amounts of these substances while taking theophylline,  increases the risk of drug toxicity. Additionally, both oral  bronchodilators and caffeine stimulate the central nervous system.  Patients may be advised not to consume GFJ when taking theophylline,  since it increases the bioavailability, and monitoring of plasma  theophylline levels in patients consuming GFJ might be helpful in better  management of patient care.

MedlinePlus-Cold and Cough Medicines

• Fexofenadine,  loratadine, rupatadine, cimetidine cetirizine, are all antihistamines.  It is best to take prescription antihistamines on an empty stomach to  increase their effectiveness. Rupatadine is commonly used for the  management of diseases with allergic inflammatory conditions. A study  indicates that concomitant intake of food with a single 20 mg oral dose  of rupatadine exhibits a significant increase in rupatadine  bioavailability. Cimetidine is given with food to assist the maintenance  of a therapeutic blood concentration. A fraction of cimetidine is  absorbed in the presence of food, allowing the remaining drug to be  dissolved once the gut is cleared. Thus, therapeutic levels are  maintained throughout the dosing interval. A study was conducted on a  latest molecule esomeprazole (acid-reducer), and it was observe that its  bioavailability was reduced when taken within 15 min before eating a  high-fat meal vs. that while fasting.

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