Posology — the first-year Pharmacy chapter on the science of dose

How much of a medicine? How strong? How often? These are the questions of posology. The word comes from Greek and means the study of dose.

The NCH syllabus gives posology chapter fifteen of HomUG-HP, first-year Homoeopathic Pharmacy. The sheet lists four topics. This piece explains each one in plain words, as a study guide for BHMS students.

Before we start, one clear line. This is a page about a subject you study. It does not tell anyone what dose to take. Dosing is a clinical decision for a qualified, registered practitioner, and this chapter is the first step of a long training in it.

Topic one: the basic principles

The first topic reads “Basic principles of Homoeopathic Posology”.

Principles are the rules underneath everything else. Before you learn any detail, you learn the ideas that decide how dose is thought about in homoeopathy.

You have already met one of them. Chapter two of the same Pharmacy sheet, “Homoeopathic Pharmacy Basics”, lists the “Law of Similia, Simplex & Minimum”. Minimum is the posology part of that law. Keep that link in mind as you study.

Write each principle as one short sentence. Then add one line on why it matters. That format works well in an exam.

Topic two: the Organon aphorisms

The second topic reads “Related aphorisms of Organon of medicine”.

The Organon of Medicine is Hahnemann’s founding book. It is written in numbered paragraphs called aphorisms. Some of them deal with dose. This topic asks you to know which ones, and what they say.

The sheet does not list the aphorism numbers. Your teachers and your Organon textbook will. When you get them, make a small table: aphorism number, the main point in your own words, and the key phrase from the text.

This topic is a bridge. Pharmacy asks for the method. Organon gives the reason. An answer that cites the right aphorism is much stronger than one that does not.

Topic three: choosing potency and repetition

The third topic reads “Criteria for Selection of Potency & Repetition of Dose”.

It has two parts. Criteria means the points used to make a choice.

• Selection of potency is about how a practitioner decides which potency to use.
• Repetition of dose is about how a practitioner decides whether and when to give the medicine again.

The sheet lists the topic but not the criteria. Your textbook does. Learn them as two separate lists, one for each part. Examiners often ask for one without the other.

To make sense of “potency” here, you need chapter twelve, “Various Scales of Potentization in Homoeopathic pharmacy”. Potency choices are made on those scales. If the scales are still unclear, go back to that chapter first.

Topic four: kinds of dose, and the minimum dose

The fourth topic reads “Various Kinds of Dose, Emphasis on Minimum Dose”.

There is more than one kind of dose, and the sheet wants you to know them. Your textbook will name and define each one. A list with one line per kind is enough to start.

Then notice the word “Emphasis”. Of all the kinds of dose, the sheet singles out the minimum dose. That is a signal. It is a key idea in homoeopathic philosophy, and it links straight back to “Minimum” in the Law of Similia, Simplex and Minimum. Expect it in exams. Be able to explain it clearly and give the Organon basis for it.

How this chapter sits in the year

First-year Pharmacy has thirty-two chapters. This is the fifteenth. It follows “External applications” and comes just before “Prescription”. The order is sensible: first you learn how dose is decided, then you learn how it is written down.

Posology does not end in first year. In the fourth BHMS year, Organon has a chapter called “Posology and remedy reaction”. So what you learn now is the base for a later, deeper study. Keep your notes. You will need them again.

What to take from it

First, know the basic principles of homoeopathic posology, and link them to the Law of Similia, Simplex and Minimum.

Second, learn the related Organon aphorisms, with numbers and key phrases.

Third, learn the criteria for choosing a potency and for repeating a dose, as two lists.

Fourth, know the kinds of dose, and be able to explain the minimum dose well.

The sheet names the topics only. It does not list the criteria or the aphorisms. This piece explains what each topic asks. The content comes from your textbook and your teachers.

Where to go next on the platform

This piece sits in the first-year Homoeopathic Pharmacy room, beside the piece on “Various scales of potentization”. The first-year Organon room covers the Organon chapters of your year. For a plain-English explainer meant for any reader, “What ‘potency’ means on a homoeopathic bottle” is in the Homoeopathic Pharmacy topic of Homoeopathy Knowledge.