Doses and concentrations
Units, dose volumes, weight-based dosing, strength, and amount of substance.
FREE FORMULAS + PRACTICE
Understand the relationship. Keep the units.
A two-page calculation companion for NAPLEX study, with 24 selected formula groups and the assumptions that make them useful.
Free, with no account required. The revised two-page guide replaces our original one-page sheet.
INSIDE YOUR DOWNLOAD
A useful reference, ready to keep beside you.
All 24 formula groups, symbol definitions, abbreviations, and brief use notes are included in the PDF. Keep a copy for study or print both pages.
Mixtures and infusions
Dilution, blending, electrolytes, pump and gravity rates, and ideal osmolarity.
Patient data and drug behavior
Body measurements, kidney-function estimates, and pharmacokinetics.
Nutrition and evidence
Parenteral energy, nitrogen, and interpreting treatment effects.
PUT IT TO WORK
Ten questions. Ten chances to explain your reasoning.
Practice dose volumes, concentrations, dilution, blending, infusion rates, electrolytes, body surface area, half-life, nutrition and number needed to treat. Each answer includes the working and one useful reminder.
Start free calculation practiceSOURCES AND SCOPE
Context belongs beside the equation.
Elementary relationships are checked by dimensional analysis. The references below provide definitions, historical equations and clinical limitations; they do not each support every formula. Definitions and explanations are included beside each formula in the PDF.
- SI mass units and prefix relationships.NIST — SI Units: Mass
Units of Mass. Unit background, not drug doses or pharmaceutical percentage definitions.
- Liter, milliliter and deciliter relationships.NIST — SI Units: Volume
Common Units of Volume. Unit background; dilution and rate equations are derived from stated definitions.
- Mole and explicit identification of molecules or ions.NIST — SI Units: Amount of Substance
Mole definition and specified elementary entities. Does not prescribe electrolyte doses or infusion safety.
- BMI calculation and screening limitations.CDC — About Body Mass Index
BMI as a measure; BMI for screening. BMI is not an automatic dosing weight.
- Corroborates the named height-weight Mosteller method.NCBI Bookshelf — Body Surface Area
Issues of Concern; reference 4 (Mosteller 1987). The original Mosteller article was not freshly read; the standard square-root grouping was independently checked.
- Exact creatinine-clearance equation, kg and mg/dL inputs, and the historical 0.85 female coefficient.Pfizer — TIKOSYN prescribing information, revised August 2023
Dosage and Administration, Step 2: Calculation of creatinine clearance. The label specifies actual body weight for TIKOSYN. This does not establish a universal weight convention for other medicines.
- Half-life, clearance, apparent distribution volume and bioavailability concepts.Clinical Pharmacokinetics in Kidney Disease: Fundamental Principles (2018)
Fundamental pharmacokinetic principles; half-life, Equation 5. First-order decay is a mathematical model; drug-specific or multicompartment parameters are not interchangeable.
- Loading and maintenance relationships and limitations of estimating drug clearance during changing kidney function.Clinical Pharmacokinetics in Kidney Disease: Application to Rational Design of Dosing Regimens (2018)
Loading Dose; Maintenance Dose; Equations 1–3; acute kidney injury discussion. Simplified model relationships do not select a clinical drug dose.
- Total energy 2,000 kcal/L, equivalent to 2 kcal/mL.DailyMed — CLINOLIPID prescribing information
11 Description. This energy value is specific to the named lipid product.
- Conventional amino acid energy factor, hydrous dextrose 3.4 kcal/g, the 16% nitrogen approximation and nonprotein calorie concepts.Berlana — Parenteral Nutrition Overview (2022)
4.1 Proteins; 4.2 Carbohydrates; 4.3 Lipids. The text prints “4 kal/g” for amino acid energy, an apparent unit typography error in calorie context. It is a clinical overview, not an exact label for every amino acid product; actual nitrogen content may differ.
- Absolute and relative effect calculations and time-specific NNT interpretation.How to appraise the effectiveness of treatment (2011)
Treatment effect size; ARR, RR, RRR and NNT worked example. Positive whole-person rounding follows the guide convention; confidence intervals require separate methods.
Original educational material. Pharmaste is not affiliated with or endorsed by NABP. Follow question-specific assumptions and current product labeling.