Polymeric Cytidine Antimetabolite Derivative for Controlled Release

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Solution Overview

Problem

Cytidine antimetabolites used in cancer and viral treatments face challenges due to rapid metabolism and excretion, leading to reduced efficacy and the need for high doses, and polymeric derivatives can induce hypersensitivity reactions and have variable therapeutic effects due to enzyme-dependent release.

Innovation Solution

A polymeric derivative of a cytidine antimetabolite is developed, where the amino group at the 4-position is amide-bonded to a carboxyl group of a polyethylene glycol moiety with a polymer having carboxyl groups in the side chains, specifically using a polyglutamic acid chain, to slow down the release of the antimetabolite and enhance therapeutic effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cytidine antimetabolites are administered at high doses to overcome rapid metabolism and excretion, then therapeutic efficacy is improved, but side effects increase and treatment safety deteriorates

Engineering Contradiction:

Improvetherapeutic efficacyVSAvoidside effects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The cytidine antimetabolite is pre-bound to a polymeric carrier (polyethylene glycol derivative with polyglutamic acid) before administration, creating a protected complex that prevents rapid metabolism and excretion. This preliminary action allows the drug to be delivered to the target site without requiring high doses, thereby maintaining efficacy while reducing side effects

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The polymeric carrier acts as an intermediary between the cytidine antimetabolite and the biological system. The carrier protects the drug from enzymatic degradation and controlled release mechanisms, enabling the drug to bypass rapid metabolism while maintaining therapeutic activity at lower doses

Inventive Principle:

Principle #24Intermediary (Mediator)

2Duration of action of stationary object

If polymeric derivatives are used to improve pharmacokinetics and reduce excretion, then duration of action is improved, but immune reaction and hypersensitivity increase

Engineering Contradiction:

Improveduration of actionVSAvoidhypersensitivity reaction

Core Design Contradiction:

Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the polymeric carrier structure by using polyethylene glycol with specific molecular weight ranges (2,000-5,000) and controlling the degree of substitution (3-100% of carboxyl groups). These parameter changes optimize the balance between prolonging drug action and minimizing immune recognition, reducing hypersensitivity reactions while maintaining extended duration of action

Inventive Principle:

Principle #35Parameter changes

3Duration of action of moving object

If polymeric derivatives with enzyme-dependent release are used, then controlled release is achieved, but therapeutic effect variability due to individual enzyme differences increases

Engineering Contradiction:

Improverelease durationVSAvoidindividual difference in therapeutic effect

Core Design Contradiction:

Duration of action of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent replaces enzyme-dependent chemical bond cleavage with a physical release mechanism based on the size and charge characteristics of the polymeric carrier. The carrier's molecular weight and structural properties enable predictable release patterns that are independent of individual enzymatic variations, ensuring consistent therapeutic effects across different patients

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The derivative achieves higher efficacy at lower doses with reduced side effects, as it slowly releases the antimetabolite independently of enzymes, providing consistent therapeutic effects and selective accumulation in affected areas.

Implementation Method 1

an amino group at the 4-position of a cytidine antimetabolite is amide-bonded to a carboxyl group of a polymeric compound

Methodology Applied

Scientific EffectAmide bonding: Chemical Bonding

Implementation Method 2

the agent release from the derivatives largely depends on hydrolysis reaction by in-vivo enzyme

Methodology Applied

Scientific EffectHydrolysis reaction: Hydrolysis

Data Source

PatentEP1881020B1Polymeric derivative of cytidine metabolic antagonist

Publication Date: 2010.08.11 NIPPON KAYAKU CO LTD

Figure 1~2

AI summary

[PROBLEMS] To provide a derivative of a cytidine metabolic antagonist which can exert a high therapeutic effect at a low dose. [MEANS FOR SOLVING PROBLEMS] A polymeric derivative of a cytidine metabolic antagonist which comprises a polymeric compound having a polyethylene glycol moiety and a polymer moiety having a carboxyl group in a side chain and a cytidine metabolic antagonist, which has such a structure that the carboxyl group in the side chain of the polymeric compound and an amino group in the cytidine metabolic antagonist are bound together to form an amide bond.