Medications Study Guide for the PTCB Exam

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Other Common and Severe Effects of Medication

Unwanted adverse (unfavorable) drug side effects are common and can range from mild to severe reactions. Patient counseling should include education about what side effects to look out for and what to do in case such side effects occur. Although all side effects are considered unwanted, most are considered negative but some might be considered positive depending on the patient, like weight loss or hair growth.

Side Effects

Side effects for a given drug can often be predicted based on how a drug works. However, since side effects are not part of the intended therapeutic effect(s) of a drug, they are considered unwanted. Common side effects may include headache, stomach upset, or dizziness; some side effects go away over time while others are expected to continue for as long as a drug is being used. In addition, some side effects may start right after administration, while others may occur after a few months or not at all. Even with the same drug, side effects may also differ by dose, dosage form, and route of administration.

Adverse Effects

Adverse effects are considered more severe than side effects and typically warrant discontinuation of therapy or possibly emergency medical attention based on severity.

Adverse events are those that negatively impact a person’s well-being or their disease management. Muscle pain and cramping are common side effects of statin medications used to treat high cholesterol. However, severe unexplained muscle pain accompanied by dark (tea-colored) urine is an adverse effect of statin medications, indicating large muscle breakdown (scientifically known as rhabdomyolysis). This would warrant discontinuation of the specific statin drug completely and a consult with the physician to seek alternative therapy.

Allergies

While a drug’s most common side effects can often be predicted, allergies are much less predictable because the body’s immune response differs significantly from person to person. Allergic reactions account for just 10% of all drug side effects; however, allergic reactions can be life-threatening. Anaphylaxis is the most serious allergic reaction and can result in hives, swelling of the face or throat, wheezing, and even death. Antibiotics are the most common cause of anaphylactic reactions. It is important to note that some patients are allergic to inactive (non-drug) ingredients, such as gluten or certain dyes; drug compounding allows for medications to be made to suit specific patient needs such as these. When asking a patient about allergies, it is important to also write down the reaction type. Anaphylaxis to a medication is considered a true allergy, while upset stomach is not.

Indications of Medications and Dietary Supplements

The indication of legend is the reason for which a prescription, OTC drug, or dietary supplement is prescribed or recommended, in keeping with the drug’s FDA approval (or legend). The dosage and duration of therapy for a drug may differ by indication. For example, the starting dose of sertraline (Zoloft®) for post-traumatic stress disorder is 25 mg once daily, but for major depressive disorder it is 50 mg once daily. Finally, if a drug is prescribed for a reason other than its indicated legend, then that drug is considered to be used “off-label”.

Drug Stability

Pharmaceutical stability is extremely important to maintain the integrity and safe use of the medication product. Regardless of whether it is a bottle of insulin or an antibiotic suspension, all medication products must be handled and stored properly to maintain the drug’s integrity. Medications can become spoiled, resulting in a loss of drug stability, and these should not be used as the potency and integrity has been compromised.

Oral Suspensions

Oral suspensions are medications that are supplied in a manufacturer’s bottle as a powder. These products can be stored at room temperature until the expiration date is met on the container. However, the powder must be mixed with the indicated amount of water prior to dispensing to become a suspension. Once mixed with water, the oral suspension must be given a beyond use date based on the manufacturer’s stability testing data. For example, amoxicillin oral suspension must be discarded 14 days after reconstitution, with recommended storage in the refrigerator.

Insulin

All insulins must be stored in the refrigerator prior to use, making it stable until the expiration date indicated on the package labeling. Once in use, it is only good for a certain amount of time depending on the type of insulin. Once in use, insulin aspart (NovoLog®) is stable for up to 28 days at room temperature, while insulin detemir (Levemir®) is stable for up to 42 days at room temperature.

Reconstitutables

Medications that are supplied as a dry powder require reconstitution with a diluent, (e.g., sterile water or 0.9% NaCl) prior to use. Many medications are manufactured in dry powder form to allow an extended shelf life. Vancomycin is an antibiotic that comes in dry powder form in a vial. This medication must be reconstituted with the correct amount of water prior to adding into an IV (intravenous) bag. Clindamycin and benzoyl peroxide (BenzaClin®) is a topical medication used to treat acne. Prior to dispensing to the patient, it must be mixed with the correct amount of sterile water and be given an expiration date of 3 months.

Injectables

Some injectables come commercially available and can be dispensed to the patient with a valid prescription, while others must be drawn up and administered in the hospital or a doctor’s office. Each has a different level of stability and expiration date based on the manufacturer’s testing data. Ceftriaxone is an antibiotic used to treat a variety of infections. Once reconstituted, it is stable for 24 hours at room temperature and can be administered intramuscularly. Dulaglutide (Trulicity®) is a subcutaneous injectable used to manage type 2 diabetes. It can be stored in the refrigerator until the package expiration date, but is only stable for up to 14 days unrefrigerated.

Vaccines

Vaccines are fragile and must be stored properly to maintain integrity and minimize deterioration. Inadequate storage and handling can lead to vaccine ineffectiveness in addition to loss of inventory and money due to spoiled product. All live and attenuated vaccines must be stored in the refrigerator between 35-46 degrees Fahrenheit, except for Zostavax. Zostavax is a live vaccine that must be stored in the freezer prior to administration. Once a vaccine is removed from the refrigerator or freezer, it should be administered to the patient without delay to decrease the risk of degradation.

Narrow Therapeutic Index (NTI) Medications

According to the FDA, narrow therapeutic index medications are those drugs “where small differences in dose or blood concentration may lead to serious therapeutic failures and/or adverse drug reactions that are life-threatening or result in persistent or significant disability or incapacity.” Examples of narrow therapeutic index medications include digoxin, phenytoin, lithium, and warfarin. These medications require patients to undergo regular blood testing to make sure the drug concentration is within the acceptable range. Concentrations below the acceptable range result in no therapeutic benefit but potential for unwanted side effects, while concentrations above the acceptable range may result in overdose and severe adverse effects.

Incompatibilities

Incompatibility occurs when two medications are mixed with each other and resulting in an unsuitable product, either by physical or chemical means. Physical incompatibilities can typically be seen while chemical incompatibilities may or may not be visible.

Physical

Physical incompatibilities typically result in a change that can be seen by the naked eye. You should always check the physical product after making the compound to make sure it is stable and compatible. Signs of incompatibility include:

  • Formation of a precipitate
  • A color change from the original product
  • Separation of the ingredients
  • Unexpected cloudiness

Note: Not all incompatibility is visible.

Physical incompatibilities have the potential to be corrected by changing the solvents, ingredient forms, suspending agents, order of mixing, etc. However, some medications are just incompatible altogether and should never be combined. An example of a physical incompatibility is the addition of calcium to ceftriaxone. This combination results in a precipitate that is lethal if administered.

Chemical

Chemical incompatibilities typically result in a change in the chemical makeup of the compounds that cannot be seen by the naked eye, but the end product is either toxic, inactive, or unstable. Some chemical reaction types that may occur between products include:

  • Change in pH
  • Decomposition/degradation
  • Hydrolysis
  • Oxidation-reduction reactions

Medication Storage

All drugs used in the pharmacy have storage requirements. Drugs can be kept at room temperature, under refrigeration, or in the freezer depending upon drug storage requirements. Some medications may also have specific storage requirements, including light sensitivity or moisture restrictions.

Temperature Ranges

Room temperature is defined as between 68 and 77 degrees Fahrenheit (F). Refrigerated drugs need to be kept at 36 to 46 degrees F. Drugs stored in the freezer are kept between -13 and 14 degrees F. If a drug has no specific storage requirements, it should be kept at room temperature.

Light Sensitivity

Some medications are sensitive to light (photosensitive) and have the potential to degrade if not stored properly. When dispensing a prescription, pills are usually counted out from the original manufacturer’s container and dispensed in a patient-specific labeled amber bottle. Amber bottles are used for dispensing as the color helps deflect rays of light. Some medications, like nitroglycerin, have special storage requirements and must be dispensed in the original manufacturer’s container.

Restricted Access

Medications that are considered controlled substances are kept within a specific restricted access area of the pharmacy. With that being said, these medications should also be kept in a safe place away from children, adolescents, and even the general public by the patient being prescribed these types of medications. Controlled substances in the category of CIII-CV, like lorazepam, zolpidem, and buprenorphine can be kept with the regular medication inventory of a pharmacy; however, some pharmacies still opt to keep them in a more restricted access area. Medications in the CII category have the highest abuse potential on the market and must be kept under lock and key, typically in a vault or cage. Examples of medications classified as CII include opioids, like oxycodone and fentanyl, and ADHD medications, like Vyvanse® and Adderall®.

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