Question

The physician has ordered nitroglycerin gr \(1 / 200\) for a client experiencing angina. How many miligrams of nitroglycerin (Nitrostat) are in one tablet of gr 1/200? a. \(0.05 \mathrm{mg}\) b. \(0.005 \mathrm{mg}\) c. \(3 \mathrm{mg}\) d. \(0.3 \mathrm{mg}\)

Short answer

There are 0.3 mg of nitroglycerin in one tablet of gr 1/200.

Step-by-step solution

Understand the Apothecaries' System

The physician's order uses the Apothecaries' System where medications are often prescribed in grains (gr). 1 grain is equivalent to approximately 64.8 milligrams. This problem requires us to convert grains to milligrams.

Convert grains to milligrams

The prescription is for gr 1/200. To convert this to milligrams (mg), use the equivalence: 1 grain (gr) = 64.8 milligrams (mg). Therefore, multiply 1/200 of a grain by 64.8 milligrams to get the number of milligrams per tablet. The equation is: (1/200) * 64.8 mg.

Calculate the dosage in milligrams

Perform the multiplication: \((1/200) * 64.8 \text{ mg} = \frac{64.8 \text{ mg}}{200}\). Simplify this to get the dosage of nitroglycerin in one tablet in milligrams.

Final Answer

After doing the math, the final answer is calculated as: \(0.324 \text{ mg}\) per tablet. Looking at the answer choices, the closest answer to \(0.324 \text{ mg}\) is \(0.3 \text{ mg}\), so the correct answer is d. \(0.3 \text{ mg}\).

Key concepts

Apothecaries' System

The Apothecaries' System is an old-fashioned way of measuring prescription medications that you might encounter in some medical scenarios. In this system, units like grains (gr), scruples (℈), and drams (ℨ) are used. Grains, in particular, are notable because they're still found in some prescriptions today. The key to using the Apothecaries' System effectively is understanding how to convert these old measurements into metric units, which are the standard in most healthcare settings now. For instance, 1 grain is approximately equal to 64.8 milligrams.

The importance of this unit conversion cannot be overstressed in scenarios such as the NCLEX-RN Examination, where precision and understanding of dosage calculations are vital. To prepare, practice converting grains to milligrams and vice versa, and remember, understanding comes from regular practice with real-world examples such as the nitroglycerin dose calculation in the given exercise.

Medication Dosage Calculation

Medication Dosage Calculation is a critical skill for nurses to master as correct dosages can be the difference between a medicine's effectiveness and toxicity. When calculating medication dosages, it is essential to have a clear understanding of different measurement systems and the conversions between them. It’s like fitting pieces of a puzzle together: knowing the patient’s prescription, the standard measurement units, and how to convert between systems tells you how much medicine to administer.

For practicing nurses and those preparing for the NCLEX-RN Examination, mastering medication calculations involves several steps: understanding the doctor's order, knowing the drug's concentration, converting units if necessary, and calculating the patient's exact dose. Practices like double-checking calculations and using a dosage calculator can help prevent medication errors. The exercise provided is an excellent example of converting a prescription from the Apothecaries' System (grains) into the metric system (milligrams) to determine the proper medication dosage.

Pharmacology for Nurses

Pharmacology for Nurses encompasses the study of how drugs interact with the human body and understanding the use, effects, and side-effects of medications. Nursing pharmacology is not just about memorizing drug names and dosages – it’s about comprehension of the therapeutics of drugs and their careful administration. For example, knowing that nitroglycerin is used for angina – as in the exercise problem – helps a nurse understand the urgency and precision required in administering the medication.

To prepare for the NCLEX-RN, nurses should focus on the pharmacological principles like the mechanism of action, the medication’s therapeutic effect, proper administration routes, potential interactions, and how to monitor patients for side effects. Real-world application examples, such as calculating the correct dose of nitroglycerin using the Apothecaries' System, are perfect for solidifying this knowledge and getting ready to apply it in clinical situations.