Medications Study Guide for the PTCB Exam
Please note that this is a study guide for the PTCB® Exam as it was revised in January 2020. It is now organized into four sections of study instead of the previous nine sections. The material covered in the new test is mostly the same as that in the old test, with a few additions that we have included here.
The 2020 version of the PTCB® Exam covers four areas of study, but the questions are not divided into sections on the actual test. This area of study, Medications, makes up roughly 40% of the test questions. That is nearly half, so you need to be very well prepared for questions on the concepts in this study guide.
The questions on Medications are mostly taken from the old test’s Pharmacology area, but also include a few concepts that were in the Sterile and Non-Sterile Compounding and Inventory Management areas of the old test. There is one new concept, Narrow Therapeutic Index (NTI) Medications, that was not listed in the content outline of the old test.
Medication Names and Classifications
Like in any other profession, knowing and using the appropriate vocabulary is an important part of the job. Being familiar with common pharmaceutical names and spellings will make it easier to understand patients and communicate with other healthcare professionals. In the realm of pharmacy, it is crucial to be exact with names and spelling, since two medications may have very similar names but be used for vastly different purposes. Typically, medications are known by both their brand and generic name. Some healthcare professionals or patients may use them interchangeably, making it imperative to know both names for each medication to establish effective communication.
Generic drugs are typically lower-cost versions of brand name drugs. A medication is produced under its brand name only while under patent (~20 years), as the pharmaceutical company who created the drug has sole rights to it. After that, other pharmaceutical companies can manufacture it under the generic name, which may also be known as the chemical name.
Brand names are typically shorter than generic names; therefore, drug manufacturers often use brand names to advertise new drugs. It is important to note that one generic drug may have multiple brand names, depending on drug formulation and manufacturer (e.g., zolpidem is found in Ambien®, Edluar®, Intermezzo®, and Zolpimist®). The first letter of a brand name should be capitalized, as it is patented by the drug manufacturer. It is important to know or at least be familiar with brand and generic names for the Top 200 medications, as they are used frequently in practice.
Pharmaceuticals are classified into drug classes based on how they work (mechanism of action) and affect the body. Often, the suffix of a drug’s generic name indicates its drug class. For example, pharmaceuticals that end with -olol (e.g., metoprolol and propranolol) are blood pressure lowering agents known as beta-blockers. Sometimes, the prefix of a drug’s generic name will indicate its drug class. For example, pharmaceuticals that begin with cef-/ceph- (e.g., ceftriaxone and cephalexin) belong to the antibiotic class of medications known as cephalosporins.
Therapeutic equivalence is designated when two drug products meet strict criteria in accordance with the Food and Drug Administration (FDA) Orange Book. Pharmaceutical equivalents, pharmaceutical alternatives, and therapeutic equivalents all fall under the umbrella of therapeutic equivalence. By law, a generic medication that shows therapeutic equivalence must be substituted for the brand name product when filling a prescription, unless a generic is not yet on the market or the prescriber deems the brand medically necessary.
Drug Interactions and Contraindications
Drug interactions occur for many reasons and can range in severity from mild to life-threatening. It is important to educate patients about the potential for drug interactions and to describe any adverse reactions they may experience.
Drugs that are used for one disease may worsen or exacerbate another disease. For example, using ibuprofen for pain in a patient with heart failure is a potential drug-disease interaction, as ibuprofen can cause fluid retention and worsen heart failure. If a patient with heart failure tolerates ibuprofen well, then the interaction is not clinically significant; however, if the patient’s heart failure worsens after starting ibuprofen, then a new approach to managing pain should be considered.
Interactions between two (or more) prescription drugs are common, can occur for a variety of reasons, and should be evaluated by the pharmacist prior to drug dispensing. Taking multiple medications, being prescribed drugs by multiple healthcare professionals, and using multiple pharmacies can increase a patient’s risk of experiencing a drug-drug interaction. Omeprazole, a medication used to treat heartburn, interacts with the metabolism of clopidogrel, an antiplatelet medication. This combination should be avoided and alternative therapy to treat heartburn should be considered. Drug-drug interactions can also occur between prescription and over-the-counter (OTC) medications as well.
St. John’s wort has the most potential for interactions with prescription drugs. For example, it has been associated with an increased risk of bleeding with the blood-thinning prescription drug warfarin and enhanced effect of prescription drugs used for depression and anxiety. Similarly, vitamin E at high doses has been associated with an increased risk of bleeding; combining vitamin E with warfarin further increases this risk. This is why it is so important when talking to patients to inquire about all the medications they take, including vitamins and supplements, and to obtain a complete medication list.
Laboratory test results are rarely affected by medications; however, because test results may be falsely positive or negative, it is important to be aware of the potential for this interaction to occur. For example, finasteride is a prescription drug used to shrink an enlarged prostate. It may reduce a man’s prostate-specific antigen (PSA), a laboratory test used to screen for prostate cancer. If laboratory results are interpreted without knowledge of the patient taking finasteride (and therefore having a falsely low PSA), it could interfere with the timely diagnosis of prostate cancer. Biotin is a vitamin that promotes hair, skin, and nail health. Taking this medication can cause false readings in many laboratory tests, including thyroid-stimulating hormone (TSH) testing.
Nutrients include vitamin supplements and nutrients from food. Calcium is an essential nutrient that can be ingested in the form of food (milk), dietary supplement (calcium supplement), or OTC drug (antacid). In any form, taking calcium at the same time as a fluoroquinolone antibiotic [e.g., ciprofloxacin (Cipro®)] has the potential to decrease absorption of the antibiotic in the body, thereby decreasing the ability of the antibiotic to fight infection.
Medication Specifications and Calculations
It is important for pharmacy technicians to be familiar with common dosages, dosage forms, strengths, and units. This will make it easier to identify the correct drug, communicate with other healthcare professionals, and even detect potential fake prescriptions. Questions on the PTCB® Exam about this topic may include calculations.
Strength and Dose
Drug strength is the amount of active drug in any given dosage form. The drug’s strength will be noted immediately after a drug name and is commonly expressed in terms of milligrams (mg) or micrograms (mcg) for oral tablets or capsules, milligrams/milliliter (mg/mL) for liquid preparations, and grams (g) for topical creams, gels, and ointments. Drugs may also be available in more than one strength. For example, tablets of the blood-thinning drug warfarin are available as 1 mg, 2 mg, 2.5 mg, 3 mg, 4 mg, 5 mg, 6 mg, 7.5 mg, and 10 mg. It is important to understand common dosing units and how to convert from one to another. For example, a prescriber might write for levothyroxine 0.025 mg, which is equal to 25 mcg as it is listed on the manufacturer’s bottle.
A drug’s dosage form is another term for its physical form. Drugs come in all shapes (e.g., tablets, capsules, solutions, creams, and patches) and sizes (e.g., 25 mcg, 500 mg, and 1 g). One important dosage form to counsel on is the suspension, as it needs to be shaken in order to evenly disperse the suspended particles and deliver a uniform dose to the patient. Some topical medications, like betamethasone, come in several forms such as an ointment, cream, and emollient.
Common administration routes include inhalation, oral, nasal, rectal, vaginal, topical, and transdermal. It is of the utmost importance to accurately identify the intended way for a drug to be given. In the case that a patient would take a capsule by mouth instead of inserting it into the rectum, drug absorption, safety, and/or efficacy may be compromised. If there is any question about the route of administration, a call to the prescriber should be made for clarification.
Special Administration and Handling Instructions
Some medications require special storage, administration, and handling instructions that are important for the patient to be aware of. Some suppositories, like promethazine (Phenergan®), must be stored in the refrigerator prior to use and should be handled with gloves, as it has the potential to melt at room temperature or even from the body heat from your hands. Also, suppositories come packaged in a foil or hard plastic wrap. These require special instructions to unwrap prior to insertion into the rectum, as many patients may be unfamiliar with proper administration techniques.
Duration of Drug Therapy
The duration of drug therapy is determined by the diagnosis and other patient-specific factors. Chronic conditions, like depression or diabetes, may require ongoing medication treatment. More acute problems, like pain or an infection, may just need to be treated for a few days or weeks. If patients take medication for less or more time than intended, it could cause problems down the road, such as uncontrolled diabetes or antibiotic resistance. The prescriber sets the duration of drug therapy for each prescription written based on the underlying condition being treated and if follow up is necessary for chronic conditions.
There are many calculations that are involved on the job as a pharmacy technician. These can range from basic arithmetic to using complex formulas. It is important to remember some clinical pearls that will help make calculations a little less daunting.
Here are some clinical pearls to remember:
- 1 mL = 20 drops
- 1 teaspoon = 5 mL
- 1 tablespoon = 15 mL
- 1 kg = 2.2 lb
- 1 in = 2.54 cm
- 1 oz = ~30 mL
- 1 pt = 473 mL
- Knowing metric system conversions is a MUST! (ex: 1 L = 1000 mL, 1 mg = 1000 mcg)
These bits of information will help you calculate strength, dosages, and duration of therapy (days supply) with ease.
Example 1: A patient is prescribed the following:
Drug: morphine sulfate 100 mg/5 mL
Directions: 5 mg by mouth every 2 hours as needed
Dispensed quantity: 30 mL
What is the day supply?
100 mg/5 mL = 20 mg/mL, so 5 mg = 0.25 mL; 0.25 mL x 12 hours = 3 mL total per day. 30 mL/3 mL = 10 days. This means that 30 mL will last the patient a minimum of 10 days.
Example 2: A patient is prescribed enoxaparin (100 mg/ml) 1 mg/kg subcutaneously every 12 hours for 7 days. The patient weighs 154 lb. What is the dosing of enoxaparin?
154 lb/2.2 = 70 kg; 1 mg x 70 kg = 70 mg; 70 mg every 12 hours for 7 days.
It is also important to understand the following concepts to make calculations easier: proportions, percentages, ratios, decimals, number rounding, and Roman numerals.
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