Theophylline Dose Calculator
The formula
What the theophylline dose tells you
Clearance-based theophylline dosing with the smoking/heart-failure modifiers — the archetype of a drug whose window is measured in single mg/L.
Calculation: Oral dose = Css × Cl × 24 ÷ (S×F); Cl ≈ 0.043 L/kg/h × smoking factor; load = ΔC × 0.5 L/kg. Enter your inputs and every substitution is shown below the result.
Reading the result
The modern target is 5–10 mg/L: bronchodilation without the vomiting and arrhythmia of the old 10–20 band.
Rules of thumb: Non-smoking adult ~400 mg/day SR; smokers often 600–800
Limitations and best practice
Acute illness, fever and ciprofloxacin change clearance within days; a stable dose is not a safe assumption.
This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Frequently asked questions
Why SR dosing first?
Is it still used?
Source & methodology
Hendales/Weinberger kinetics; BTS guidance.
Theophylline Dose: the number, the method and the caveats
Health numbers only mean something against a reference — this page gives you both the number and the band it sits in. Searchers land on a Theophylline Dose page for three reasons — to plan, to compare options, and to check that somebody else’s arithmetic is honest. This tool serves all three, and everything after the calculator explains the model instead of hiding it.
A calculation like this one is worth roughly as much as a careful sentence: it forces several vague considerations into one comparable quantity. Once Theophylline Dose is on the table, the argument can stop being about impressions.
The useful way to hold Theophylline Dose is as a ratio with a story attached: Oral dose = Css × Cl × 24 ÷ (S×F); Cl ≈ 0.043 L/kg/h × smoking factor; load = ΔC × 0.5 L/kg says how the parts combine, and the 0 mg/day figure above is simply that sentence written in numbers. Everything that follows unpacks one clause of the sentence at a time.
Every figure in the prose is generated by the engine rather than written beside it — the worked example resolves to SR dose = 0 mg/day on the default inputs. Work down the page and by the end you could re-derive the result in a spreadsheet from memory.
The Theophylline Dose formula, explained
The engine implements a single stated model: Oral dose = Css × Cl × 24 ÷ (S×F); Cl ≈ 0.043 L/kg/h × smoking factor; load = ΔC × 0.5 L/kg. There is no hidden coefficient and no login-gated precision — the formula printed is the formula executed, which is also what makes the result citable.
Weight (kg) (example value 46) is a numeric input whose unit is fixed by the label; a wrong unit is a wrong answer wearing a plausible disguise. Use the same conditions each time (same scale, same time of day) so that changes in the output reflect real change.
Target (mg/L) (example value 14) is a quantity rather than a category — precision here is cheap and worth having. Figures of this kind carry safety consequences; when in doubt, use the conservative value and confirm with a professional.
Smoking status (example value 0) is a choice rather than a quantity — pick the option that matches your situation, because the calculation path branches here. The example value is there to demonstrate the mechanics, not to describe your situation — overwrite it.
Current level (mg/L) (example value 4) is a quantity rather than a category — precision here is cheap and worth having. Figures of this kind carry safety consequences; when in doubt, use the conservative value and confirm with a professional.
What each “Smoking status” choice actually does: Non-smoker → 738 mg/day · Smoker (induced) → 1,182 mg/day · Heart failure/hepatic → 443 mg/day — each value above is the model’s own output for that option, so the choice can be made on evidence rather than on what a category feels like it means.
A fully worked Theophylline Dose example
Rather than describe the calculation, here it is end to end — every substitution in order, starting from the inputs above. Starting figures: Weight (kg), Target (mg/L), Smoking status, Current level (mg/L). Run to the end, the SR dose resolves to 0 mg/day — Clearance of 0.00 L/h gives a sustained-release requirement of ~0 mg/day for 14 mg/L; if acutely below range, a 288 mg aminophylline-equivalent IV load closes the gap in hours on the bands this tool uses.
- Cl = 0.043 × 46 × 0.0 = 0.00 L/h
- Dose = 14 × 0.00 × 24 ÷ 0.9 = 0 mg/day
- Load = ΔC × 0.5 L/kg ÷ 0.8 = 288 mg
Clearance — 0.00 L/h. Read next to the headline, this is the figure that shows the shape of the trade-off.
IV loading dose — 288 mg. This is the number experienced users quote when the headline alone would mislead.
Twice-daily split — 0 mg. Compare it against the main result of 0 mg/day before drawing conclusions.
Interaction flag — ciprofloxacin/macrolides halve clearance. If your inputs change, this is usually the first companion figure to move.
Overwrite any input above and every line of this example updates with it — the substitution is live, not a screenshot of somebody else’s numbers.
What a Theophylline Dose of 0 mg/day means in practice
A number on its own is trivia; a number against a range is intelligence. The verdict attached to the default calculation — “Clearance of 0.00 L/h gives a sustained-release requirement of ~0 mg/day for 14 mg/L; if acutely below range, a 288 mg aminophylline-equivalent IV load closes the gap in hours” — is one band on a ladder your own figure may sit somewhere else on. The practical reading rules: read the band as a starting hypothesis, then test it: change the two dominant inputs by ten percent and see whether the verdict survives. Verdicts that survive stress are the ones worth acting on.
Set Theophylline Dose beside its neighbours and it usually plays a specific role: this figure establishes the size of something, and the neighbouring tools establish whether that size is acceptable. Skipping the first step makes the second one arbitrary.
The errors that quietly break a Theophylline Dose figure
Acute illness, fever and ciprofloxacin change clearance within days; a stable dose is not a safe assumption. This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Reusing a Theophylline Dose from last season. In Health & Medical the inputs are the thing that drifts; the formula does not.
The subtlest error is answering the wrong question precisely. Confirm that SR dose is actually the quantity your decision needs — the arithmetic is flawless either way, which is what makes the mistake invisible.
Theophylline Dose verification checklist
- Record the date and the inputs alongside the number so future-you knows what was assumed.
- Re-run the calculation with a ±10 % stress on the two most sensitive inputs.
- Confirm the inputs are dated — a Theophylline Dose figure should carry the date it was computed.
- Compare the output against one published benchmark or a colleague’s independent estimate.
- Confirm the example values are plausible for your own situation before replacing them.
- Confirm the answer against one independent method or published benchmark for Theophylline Dose.
Step by step: getting a trustworthy Theophylline Dose out of this tool
Using a calculator well sounds trivial, but the difference between a decision-grade figure and a throwaway one lives entirely in the routine. The routine for Theophylline Dose takes a minute to learn and applies to every input above.
Step 1 — one document, one pass. Open the statement, label or record that holds weight (kg), target (mg/l), smoking status, current level (mg/l) and transcribe straight into the form. Transcription from a single source removes the mismatch errors that appear when figures are assembled from three different places. Numbers are cheap to produce and expensive to retract; the extra minute is the cheapest insurance available.
Step 2 — compute the version you would not be embarrassed by. If a stranger audited your inputs, which set would you hand over? Enter that set, read the result, and treat everything else as upside. One decimal place more than your data supports is one decimal place of fiction.
Step 3 — change one input at a time. Nudge a single field by ten percent, watch the headline and its companions move, then undo it. Two or three fields will dominate — the sensitivity table above already ranks them for this engine. Note the assumption you are least sure about; that is where the real risk lives.
Step 4 — run the scenario trio. Expected, pessimistic, optimistic. The gap between pessimistic and expected is the number to plan against; the optimistic result is useful only as a ceiling. One decimal place more than your data supports is one decimal place of fiction.
Step 5 — record the context, not just the number. Note today’s date and the inputs alongside the 0 mg/day output. Six months from now the context is what turns this figure into a trend. The point of transparency is that a reader can disagree with a specific line rather than with you.
The real-world conversations Theophylline Dose settles
Most Medications & Dosing disagreements are arithmetic disagreements in disguise. When SR dose of 0 mg/day sits on the table with its working shown, the conversation stops being about who sounds more confident and starts being about which input is wrong. Write the assumptions in the same file as the result, and future arguments take minutes instead of meetings.
Professionals in Medications & Dosing use this style of calculation as a screening filter before spending real money or effort: a quick Theophylline Dose check eliminates weak options in minutes, and the survivors earn the deeper, slower analysis. The test of a good estimate is not that it feels right but that it changes what you do.
Treat Theophylline Dose like a smoke alarm rather than a painting — its value is in being tested periodically, not in being admired once. When in doubt, prefer the boring input: the interesting one is usually the one you misread.
People also ask about Theophylline Dose
How much does the “Smoking status” choice change the answer?
The spread is not cosmetic: this choice alone takes Theophylline Dose from 443 mg/day to 1,182 mg/day with every other input frozen, which is more influence than most of the numeric fields on this page can claim.
What is a typical Theophylline Dose?
With the example inputs on this page the result is 0 mg/day, labelled “Clearance of 0.00 L/h gives a sustained-release requirement of ~0 mg/day for 14 mg/L; if acutely below range, a 288 mg aminophylline-equivalent IV load closes the gap in hours”. “Typical” varies with situation, which is why every result here ships with its verdict band and its sensitivity list: they turn one figure into a range you can locate yourself inside.
How do I calculate Theophylline Dose by hand?
Three steps: write the formula (Oral dose = Css × Cl × 24 ÷ (S×F); Cl ≈ 0.043 L/kg/h × smoking factor; load = ΔC × 0.5 L/kg), insert your values, and simplify. The worked example section shows exactly that chain for the default inputs; replicating it once on paper teaches you more about Theophylline Dose than any number of calculator runs.
Is the Theophylline Dose result of 0 mg/day good or bad?
The tool answers “what”, not “whether”: 0 mg/day carries the verdict “Clearance of 0.00 L/h gives a sustained-release requirement of ~0 mg/day for 14 mg/L; if acutely below range, a 288 mg aminophylline-equivalent IV load closes the gap in hours” for the default case, which is a starting interpretation rather than a verdict on your situation. Re-run with your own figures and compare the bands.
What affects Theophylline Dose the most?
Sensitivity depends on where you start, but the inputs Weight (kg) and Target (mg/L) typically move Theophylline Dose further than the rest because they enter the formula multiplicatively. If you can only measure two things well, measure those and hold the others at conservative defaults.
How do I calculate Theophylline Dose manually?
Write down the inputs, then follow the printed steps in order — Oral dose = Css × Cl × 24 ÷ (S×F); Cl ≈ 0.043 L/kg/h × smoking factor; load = ΔC × 0.5 L/kg. A spreadsheet replicates it with two or three cells. The manual route is worth doing once to build intuition; after that the calculator saves time and eliminates transcription slips.
Why SR dosing first?
Immediate-release four-times-daily regimens swing levels; the SR formulation is the whole point of measuring levels at trough.
Is it still used?
As add-on in difficult asthma/COPD with documented reversibility — its narrow index keeps it second-line.
Do I need an account to use this Theophylline Dose calculator?
No, and no data leaves the tab. The engine runs in the page itself, which is why the worked example, the bands and the sensitivity ranking all respond instantly to your keystrokes.
What the labels on this page mean
- Clearance
- 0.00 L/h on the example inputs — a companion figure printed beside the headline of Theophylline Dose so that no result is read in isolation.
- IV loading dose
- 288 mg for the Theophylline Dose worked case; it sits next to the main result because it carries context the headline leaves out.
- Twice-daily split
- 0 mg in the default Theophylline Dose calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- SR dose
- The primary output of this tool: 0 mg/day for the default inputs, computed exactly from Oral dose = Css × Cl × 24 ÷ (S×F); Cl ≈ 0.043 L/kg/h × smoking factor; load = ΔC × 0.5 L/kg.
- Worked example
- The step-by-step substitution printed above, so the arithmetic can be re-derived by hand or in a spreadsheet.
- Verdict band
- The interpretation attached to a result (“Clearance of 0.00 L/h gives a sustained-release requirement of ~0 mg/day for 14 mg/L; if acutely below range, a 288 mg aminophylline-equivalent IV load closes the gap in hours” on these inputs), which turns a bare number into a position on a scale.
Method, sources and what this tool cannot tell you
The model is published arithmetic implemented exactly as written: Oral dose = Css × Cl × 24 ÷ (S×F); Cl ≈ 0.043 L/kg/h × smoking factor; load = ΔC × 0.5 L/kg. Source of record: Hendales/Weinberger kinetics; BTS guidance. Specialist software layers extra coefficients on top of the same algebra; none are hidden here, and that transparency is what makes a disagreement traceable to a specific input instead of a black box.
Treat the output as a precise answer to the question you typed: exact arithmetic, transparent formula, published source, no hidden rounding. The design constraint was set by usefulness rather than by comfort: an estimate you can interrogate beats an answer you have to trust.
What to do with your Theophylline Dose next
Re-measure on a second occasion before changing behaviour; single readings carry natural day-to-day variation.
The audience here is people checking a personal health figure before acting on it. Everything you need to defend the result — formula, substitution, sensitivity, source — is printed above, so the only remaining variable is the honesty of your inputs.