@zenuinebit/prescription

Helpers for writing prescriptions: dosing frequency, quantity to dispense, dose by body weight, and a printable layout. No dependencies.

These helpers do arithmetic and formatting only. They know no drug, check no interactions and do not decide whether a dose is safe. A qualified clinician must review every prescription and dose.

import {
  parseFrequency, describeFrequency, quantity, courseEnd, administrationTimes,
  weightBasedDose, liquidVolumeMl, renderText, renderHTML,
} from "@zenuinebit/prescription";

describeFrequency("1-0-1");                       // "1-0-1 (morning, night)"
quantity({ frequency: "TDS", days: 5 });          // { units: 15, dispense: 15 }
quantity({ frequency: "OD", days: 5, unitsPerTake: 0.5, packSize: 10 }); // { units: 2.5, dispense: 3, packs: 1 }
courseEnd("2025-03-01", 5);                       // "2025-03-05"
administrationTimes("TDS");                       // ["08:00", "15:00", "22:00"]

// Weight-based: say whether the figure is per dose or per day, there is no default
weightBasedDose({ weightKg: 12, mgPerKg: 15, basis: "per-dose", dosesPerDay: 3, maxSingleMg: 500 });
// { singleMg: 180, dailyMg: 540, capped: false }
liquidVolumeMl(180, { mg: 125, ml: 5 });          // 7.2 (ml)

renderText(rx);    // plain text for chat or a thermal printer
renderHTML(rx);    // A5 page to print; all text is escaped

Frequencies understood: OD, BD, TDS, QID, HS, STAT, SOS/PRN, Q4H/Q6H/Q8H/Q12H (dots and case ignored), and morning-afternoon-night notation like 1-0-1 or 1-1-1-1. In that notation each number is a multiplier of unitsPerTake.

Good to know

• SOS/PRN medicines need maxPerDay before a quantity can be worked out.
• Maximums in weightBasedDose lower the dose and set capped: true. Rounding never pushes a dose back over its maximum.
• courseEnd counts the start day as day 1.

Not included: a drug database, interaction or allergy checks, renal or paediatric dosing rules, and digital signatures.