From the standpoint of patent laws, every patent application is allowed to cover one invention only or a group of inventions linked by a unifying underlying concept. For instance, a product and a process especially adapted for the manufacture of that product; a process and means for carrying out the process are widely accepted as constituting unity.

In chemical and pharmaceutical product patents, a single claim covering alternatives of a new chemical entity (NCE) in the so-called Markush grouping format is well-recognized as belonging to one invention provided each alternative is believed to have a common property or activity; a common basic structure; or a technically closely related chemical structure. The rationale behind this extended scope of protection is to stop competitors from bringing obvious modifications or variations in the structure not sufficient to alter the character or identity of the claimed compound. Also, added to this extended scope are “salts” which is the ultimate commercial form in which a compound is sold.

With the exclusion of derivatives and salts, exhibiting substantial advantages or improvement in their activity over the compound in free acid or base form from the scope of single invention, the Pakistan Patent Ordinance 2000 sets out a substantially similar criteria for unity as adapted elsewhere. In this context, based on the well-settled principle of “sound prediction” generally associated with a generically drawn and hierarchically arranged product claims for a NCE, the Pakistan Patent Office (PK-PO) has allowed derivatives/variants/analogues etc. of the active compound having the potential for similar utility to be bracketed in a single application.

Against salts of the NCEs, “one compound one application” theory as floated by some patent examiners has forced many applicants either to abandon rights over salts or adopt the divisional application route to protect them regardless that salts by their very nature do not alter the scaffolding or basic molecular structure of the base compound and upon administration generally metabolize first to the active compound and while reaching to its target takes the ultimate form of a solution (body fluids) leveling all previous differences in forms. Unless exhibiting some substantial advantages over basic compound, to pursue salts and any variants analogue/derivatives in a divisional application with specification lacking  a disclosure of improved characteristic, and any example showing compound in salt form, may invite insufficiency and validity issues at any stage of the term of patent. A carefully scrutinized and devised filing strategy was never needed before as is now required in the ever changing and complex world of Intellectual property.