Heat Sensitive Magic: Unveiling Thermochromic Substances in Pharmacy

Abstract

Thermochromic substances are materials that change it’s colour when there is change in external stimuli like temperature or excessive heat1, this unique property can be used for transport and packaging of pharmaceuticals2 . Thermochromic substances are type of chromogenic materials1 , This system can be used for temperature sensitive drugs and pharmaceutical materials that need suitable environmental conditions for storage and transport6, In pharmaceutical market use of this materials are increasing as it can be cost effective to use and easily detectable, this review focuses on Introduction of Thermochromic substances it’s system, pharmaceutical growth of this substances, Applications in varies field, future trends and challenges in pharmaceuticals market14.

Keywords

Introduction

Fig:1.1) Types of Thermochromic Substances.

Photochromic materials: These are the materials Having different absorption spectra when they exposed to light they undergone reversible transformation ²

This is the basic principle of Thermochromic materials they respond to fluctuations in temperature and structural change can be seen in these materials ⁷ When there is negative temperature the structural shape of molecule will contract and after the contract, they will show different colour e.g. Blue ⁵ When there is positive temperature the structure of the molecule will expand and after the structural change, they will show different colour e.g. Red ⁵

Leucodyed based Thermochromic materials:-  This materials use the leuco dyes they respond to temperature shift and change there colour  examples can be , ex. Leucodyed based , thermochromic ink³

Fig 2.1) Market Size Growth.

3.Application of Thermochromic materials in pharmaceutical products

Thermochromic materials in pharmacy have vide range of  applications ,  in recent advance technologies thermochromic materials use in analysing of pharmaceutical products

3.1Thermochromic materials in temperature sensitive packaging :

Form the 1960 the temperature sensitive packaging is used for pharmaceutical industry first in 1960 the researcher start to use this materials in packaging ¹⁸

• First commerical use of thermochromic materials in pharmacy:

First commercial use of thermochromic materials in pharmaceutical industry was in 1990 when company, colorchange, introduced a temperature sensitive packaging systems for use in pharmaceutical industry. ⁴This system known as “colour change temperature indicator ” , used as thermochromic material to change colour in response to temperature changes , indicating whenever pharmaceutical product had been exposed to excessive heat or cold it is very important to analyze that pharmaceutical products, importantly parentrals are being in right temperature for storage¹⁰.

3.2Types of thermochromic materials in packaging:

Thermochromic materials in packaging can be varies by types for they use.

• Thermochromic materials in packaging of food: 

This are the materials that can be used to indicate that food in packaging is safe for intake or it expired, It is used in most of the packaging food . The thermochromic materials on labels change it colour indicating the expiry of food ^11.

• Thermochromic materials in pharmaceutical package:

It uses is growing across the world as it is consider safe to use for packaging, in pharmaceutical industry the pharmaceutical products are directly related to patient safety so it consider as safe for pharmaceuticals so it use as a indicator for packaging like tablet’s , paediatric pharmaceutical products etc. , Temperature is key factor that need to determine for storage as right temperature essential for potency and efficiency of pharmaceutical products^{6 18}

3.3Thermochromic labels:

This can indicate if pharmaceutical products expose to heat or cold, it provides a visual indication  And this labels are made from Leucodyes or liquid crystals that alter the molecular structure when exposed to different temperatures⁷  , this labels mainly use when vaccine, injections , insulin and antibiotics  are stored and transported at correct temperature , Leucodyes are organic carbon based chemical and thermochromic ink .¹⁰ Thermochromic labels give easy – to – see guarantee that product is safe to use they activated in both heat activated and cold activated versions.¹²

4.FUTURE TRENDS IN THERMOCHROMIC SUBSTANCES

Thermochromic materials hold immense growth potential to evaluate temperature monitoring in pharmaceutical industry, when currently this materials are use in packaging and transport future applications and research can expand this use into more advanced and integrated systems , some can be :

4.1Enhanced Shelf life and stability –

Uv-light sensitive thermochromic pigments that can be highly resistance to UV light, humidity and chemical resistance ¹⁷

4.2Eco friendly and Biodegradable system –

To develop non – toxic Thermochromic agents like (anthocyanin’s , curcumin) and to reduce environmental impacts ^{11 23}

4.3Smart sensors development –

Combination of thermochromic indicators with RFID, NFC, or IoT-based devices to create hybrid smart packaging that can be capable of recording, storing, and transmitting temperature data.²⁴

4.4Broader Pharmaceutical Applications – Applying thermochromic coatings directly to dosage forms such as tablets, syrups, or injectable vials to provide real-time patient-level assurance of product safety.²⁵

4.5Personalized Medicine and Patient Compliance –

 Using colour-change indicators in patient-specific kits to help and alert users about improper storage or missed doses, improving treatment outcomes.²⁶

4.6Regulatory Standardization –

Establishing global guidelines for the use of thermochromic materials in pharmaceutical packaging to ensure safety, accuracy, and reliability across markets.^{27 28.}

4.7Cost-Effective Manufacturing –

Scaling up low-cost production methods, including roll-to-roll printing and microencapsulation techniques, to make thermochromic systems accessible for mass use in developing nations.³⁰

5.CHALLENGES:

5.1Overcoming stability and scalability issues:

• Stability – Many organic thermochromic pigments, particularly leuco dyes, are prone to UV degradation, humidity sensitivity, and chemical interference. This can lead to faded or inaccurate colour responses over time. Solutions include microencapsulation, UV-protective coatings, and the development of inorganic or hybrid pigments with higher thermal and photo stability.^{3 9 17.}
• Scalability – Large-scale production faces hurdles such as high encapsulation costs, maintaining uniform pigment performance, and integrating thermochromic systems into existing packaging lines without affecting product integrity. Advances in roll-to-roll printing, low-cost polymer carriers, and automated quality control systems are key to making thermochromic technology more affordable and accessible.^{27 28 29.}

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