A small-dose iron tolerance test was used to compare absorption of iron with and without various antacids. Liquid antacid containing aluminum hydroxide and magnesium hydroxide did not significantly decrease iron absorption. However, when calcium carbonate was present in a multivitamin-plus-minerals tablet, the plasma iron change was not significantly different from control trials.
Presumably the competitive binding of iron by ascorbic acid in the vitamin pill allowed uninhibited absorption of the iron. Our results suggest that certain antacids may be combined with iron therapy without reducing the efficacy of the iron. Coronavirus Resource Center. Our website uses cookies to enhance your experience. This is incorrect, because the mg weight is based on a chemical formula containing seven waters of hydration. Choice E is the amount of anhydrous ferrous sulfate present in each mg.
The question asks for iron Fe only. What weight of the chemical is needed to obtain 40 mEq of calcium? Or, the problem can be solved by the following equation:. It must be remembered that 40 mEq of calcium combines with 40 mEq of chloride to form 40 mEq of calcium chloride.
A, incorrect —This answer is obtained if one multiplies the 40 mEq desired by the atomic weight of calcium and then divides by the valence of 2. The use of the atomic weight of calcium is incorrect because the official hydrated calcium chloride is being weighed to obtain the correct amount of calcium.
The right answer can be obtained by adding the following step:. C, incorrect —The answer of 2. However, the problem specified that the official form, which contains two waters of hydration, was available. E, incorrect —The answer of 5. How many grams of magnesium is present in every mL dose? Magnesium carbonate has the structure of MgCO 3 therefore,. How is this concentration in terms of ppm expressed? The concentration of mercury in a water sample is reported as 5 ppm.
How is this concentration expressed as a percentage? Mercury is a solid chemical. Thus, the 5-ppm concentration indicates 5 g of mercury per 1,, mL of solution. Therefore, the grams present in mL will be.
Step 1—Determine the drug concentration present in every milliliter. Step 2—Determine the milliliter needed to obtain the concentration requested.
Step 3—Calculate the number of drops needed, based on the administration set being used, to obtain the required volume. A pharmacist places mg of a drug into mL of normal saline solution. Forgot Username? About MyAccess If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.
Learn More. Sign in via OpenAthens. Sign in via Shibboleth. AccessBiomedical Science. AccessEmergency Medicine. Case Files Collection. Clinical Sports Medicine Collection. Davis AT Collection. Davis PT Collection. Murtagh Collection. About Search. Enable Autosuggest. You have successfully created a MyAccess Profile for alertsuccessName. Previous Chapter. Next Chapter. Hall G. Gary D. Hall, and Barry S. McGraw Hill; Accessed November 14, APA Citation Pharmaceutical calculations.
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View Table Download. Ansel HC. Pharmaceutical Calculations , 13th ed. Philadelphia, PA: Wolters Kluwer, Troy DB. The volume in question is often a solution , which involves a substance called a solute in this context dissolved in a liquid called a solvent.
When solid dissolves in a solvent to create a solution, the concentration of the solution can be expressed in a variety of ways. This relates to the fact that chemicals react with each other not on the basis of mass but on the basis of the ratio of individual "pieces," regardless of size. The concept of moles and equivalents, and thus millimoles and milliequivalents , underlies this relationship, and it is of vital importance in medicine and clinical pharmacology. In an example of a simple chemical reaction, one atom of potassium K can react with one atom of chlorine Cl to form a molecule of potassium chloride KCl with nothing left over.
But this is not because potassium atoms and chlorine atoms have the same mass. Instead, it is because K and Cl react in a 1-to-1 molar ratio. A mole consists of 6. Every element's molar mass , or the mass of a single mole in grams is given in the periodic table of elements see the Resources for an online version.
Loop diuretics increase the excretion of calcium, while drugs that affect vitamin D which promotes of calcium absorption , such as phenytoin, phenobarbital, and orlistat, may decrease the amount of calcium absorbed from the diet. Pharmacists are in a key position to speak with patients taking these medications and to recommend adequate calcium intake and supplementation, particularly for patients with other risk factors for osteoporosis.
Aluminum and Magnesium: Aluminum and magnesium are unlikely to be used solely as supplements; however, they are found in common over-the-counter antacid products.
Like calcium, they can bind to vulnerable medications, decreasing their bioavailability and lessening their efficacy. Fluoroquinolone and tetracycline antibiotics, bisphosphonates, and levothyroxine may be affected by aluminum and magnesium; therefore, doses of these drugs should not be taken within two hours of aluminum or magnesium consumption.
If the patient is not responding to therapy as expected, the pharmacist should recommend that the aluminum or magnesium product be discontinued and an alternative identified. Iron: Iron supplements are needed if the body cannot produce a sufficient amount of red blood cells. Lack of iron may lead to tiredness, shortness of breath, decreases in physical performance, learning problems, and an increased risk of infection.
Patients taking iron supplements or multivitamins that contain iron should be instructed to avoid taking their supplement within two hours of a dose of tetracycline or fluoroquinolone antibiotics, digoxin, or levothyroxine.
If this is not possible, the dose of the levodopa should be increased. Iron can also cause worsening of hypertension in patients taking methyldopa, and concomitant administration is not recommended. Interactions between iron and omeprazole, which was recently switched to over-the-counter status, may not be easily identifiable; therefore, pharmacists should question patients about their consumption of omeprazole and iron supplements. Potassium: Although most patients taking potassium supplementation receive this mineral in the form of a prescription product, some over-the-counter products contain potassium.
Any medication that increases potassium levels in the body has the potential to interact with supplemental potassium. Patients should use caution when taking extra potassium if they take any of the following prescription medications: angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, digoxin, indomethacin, prescription potassium supplements, and the potassium-sparing diuretics triamterene or spironolactone.
While the amount of potassium found in over-the-counter vitamin and mineral supplements is unlikely to cause major interactions, the pharmacist should warn patients of the potential for interaction, particularly if the patient is at risk for renal insufficiency.
When counseling patients about the importance of avoiding excess potassium, pharmacists should mention that most common salt substitutes available in supermarkets contain potassium; therefore, these products should be avoided in patients at risk for hyperkalemia. Considering that a mEq prescription tablet contains mg of potassium, a patient can easily accumulate potassium if using a salt substitute and thus should be warned against consuming these products if taking medications that retain potassium.
Conclusion There are many different types of drug interactions with vitamins and minerals, ranging in severity and significance. Patients may not think to share information with their pharmacist about the vitamins and minerals they take, or they may feel the substances are harmless and irrelevant to their medication regimen. Because of the likelihood of an interaction, pharmacists should question patients not only about the drug allergies they have but also about the vitamins and minerals they ingest daily.
Although this article did not discuss herbal products and other nutraceuticals, use of these products is important to document as well. Without this information, pharmacists cannot provide the necessary screening for interactions. Information about the use of vitamins, minerals, herbal products, and other nutraceuticals should be documented in patients' records for future reference. In addition, pharmacists should encourage software vendors and employers to provide fields in their profile systems for over-the-counter medications and supplements, since these products can impact care and cause easily avoidable drug interactions that could put the patient at risk for poor outcomes or adverse effects.
Am J Epidemiol. Pyridoxine antagonism of levodopa in parkinsonism. Hansson O, Sillanpaa M. Letter: Pyridoxine and serum concentrations of phenytoin and phenobarbitone. Coagulopathy associated with vitamin E ingestion. Schrogie JJ. Coagulopathy and fat-soluble vitamins.
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