Unlocking the benefits of mannitol through the right grade selection

Mannitol is one of the most established excipients in pharmaceutical development. It is valued as a reliable filler in solid oral dosage forms, due to its low hygroscopicity, chemical stability, and pleasant taste. But its full potential goes far beyond basic filler functionality. Intrinsic characteristics like crystallinity and particle size, as well as external factors like the manufacturing process, all influence mannitol’s properties and performance. This means that with the right process and grade selection, formulators can unlock a much broader range of formulation benefits.

In this blog post, Roquette explores four of these underutilized benefits spanning – manufacturing efficiency, sensitive active pharmaceutical ingredient (API) protection, and the development of more patient-centric oral solid dosage forms.

1. Greater control over tableting outcomes – if you know which grade to choose

Mannitol’s polymorphic form is one factor that can influence tableting performance. Polymorphism is the ability of a substance to exist in different crystal forms, which may behave differently during manufacturing and in the final dosage form. Mannitol exists in three polymorphic forms (α, β, and δ), each with distinct crystal structures that influence stability, solubility, morphology, and compactability in different ways. The β-polymorph offers the greatest stability and the most predictable behavior under compression, but it is not the only form available. Roquette Pharma and Consumer Healthcare’s PEARLITOL^® 200 SD, for example, contains both α and β polymorphs and remains stable in the dry state, since the α-to-β transition only occurs in the presence of water – and mannitol has very low hygroscopicity.

How mannitol is produced influences its crystal growth too. The specific mannitol production method affects its polymorphic composition, particle morphology, density, and surface area. Roquette uses different technologies to produce different polymorphs and grades of mannitol. Crystalline grades are produced via a crystallization technique, then milled and sieved to achieve different crystal sizes, while directly compressible (DC) mannitol relies on proprietary extrusion and spray-drying technologies, yielding either a pure β-polymorph or an α/β combination depending on the method used. These engineered particles behave differently during manufacturing. Extruded mannitol is homogenous and dense, making it well-suited to sachet applications and some tablet formulations. Spray-dried grades, by contrast, have porous particles with good flow and compressibility, ensuring homogeneity, tablet weight consistency, and better tabletability. Granulated grades are dense and less porous, making them suitable for tableting, sachet formulations, and mini-tablets. Selecting a specific, well-controlled grade of mannitol, in other words, gives formulators more predictable and consistent performance during tablet manufacturing.

At Roquette Pharma & Consumer Healthcare, we enable formulators to do this through our extensive mannitol portfolio, offering distinct grades engineered with different properties to match specific manufacturing needs.

2. A viable route to direct compression – even at high drug loads and speeds

Advances in particle engineering have led to mannitol grades with different porosity and density profiles, which can help support direct compression in formulations that may otherwise require wet granulation. In some cases, replacing wet granulation with direct compression can also reduce the risk of nitrosamine formation, particularly where vulnerable amines and nitrites are present. This is because wet granulation promotes the distribution and mobility of both nitrites and amines, increasing the chance of contact, reactivity, and potential nitrosamine formation – a risk that direct compression avoids, since it removes exposure to the solvents and drying temperatures that enable this mobility.

Case study: Melatonin mini-tablets

Mini-tablets are an attractive dosage format for addressing swallowability issues in certain patient populations, such as geriatric and pediatric patients. They can also help solve multi-drug compatibility issues, since mini-tablets of individual APIs can be combined within a single capsule. Moreover, this mini dosage format can be easily coated and packed into multi-unit packaging systems like bottles or sachets. However, due to their small size, mini-tablets are highly sensitive to tooling and flow behavior, meaning excipient choice is critical to maintaining robust manufacturability. PEARLITOL^® 200 GT, a granulated crystalline powder and direct compression grade of β-mannitol, is a preferred excipient for this application, offering physical properties well-suited to mini-tablet production. It simplifies the manufacturing process: simply blend the API with PEARLITOL^® 200 GT and lubricant, then compress into tablets.

Commercially available melatonin tablets typically contain around 5 mg of the active in a 300-500 mg tablet, making them difficult for some patients to swallow. Using our granulated, high-density, low-porosity PEARLITOL^® 200 GT in direct compression, we were able to compress the formulation into mini-tablet form – reducing its diameter from 10 mm to 2.5 mm, while still achieving 5 mg of the active in a 15 mg tablet. The result was a significant reduction in both tablet size and weight, making the mini-tablets easier to swallow. It also lowered total cost, since less excipient was needed and production ran faster. This case illustrates how the right mannitol grade paired with direct compression processing can enable highly compact, patient-friendly mini-tablets without compromising manufacturability.

3. An extra layer of protection for sensitive APIs

Some of the most widely used drug molecules – including antidepressants, antihypertensives, antidiabetics, and anti-allergy therapies – contain amine groups that can react with reducing sugars, such as those found in excipients like lactose. This is usually via a non-enzymatic chemical reaction known as the Maillard reaction, which can lead to degradation and stability issues that could impact the quality and efficacy of the finished drug product.

Therefore, for those formulating with sensitive APIs, using an excipient that reduces the risk of the Maillard reaction occurring is essential. When it comes to mannitol, while it is not a reducing sugar itself, it can contain reducing sugars like mannose and glucose. That’s why we offer PEARLITOL^® 150 SD, a spray-dried mannitol grade specifically developed for sensitive APIs. It has a reducing sugar specification of just 300 ppm – with measured values consistently below 150 ppm – offering an extra margin of protection for APIs sensitive to reducing sugars.

4. A natural advantage in high-speed manufacturing

Materials that deform plastically tend to flow and flatten under pressure, requiring higher forces and exhibiting stronger sensitivity to lubricants and compression speed. In contrast, brittle materials like mannitol fracture into smaller particles during compaction, creating new contact surfaces that help bonds form. This makes them less sensitive to lubricants, speed variation, and equipment differences than plastic materials – resulting in formulations that are more robust and easier to scale up.

Mannitol’s mechanical behavior under compression can be a limitation though, as it may lead to capping. To address this risk, purpose-engineered PEARLITOL^® 200 GT, a granulated mannitol excipient, can help. With its high density, excellent flow, and good compactability behavior, it can solve capping-related challenges. Indeed, the excellent compressibility of PEARLITOL^® 200 GT enables high-speed production with improved productivity and efficiency without compromising tablet hardness.

Rediscover mannitol with Roquette’s Health & Pharma Solutions

With our full range of mannitol grades and additional excipients, combined with our extensive technical and formulation expertise, Pharma and Consumer Healthcare Solutions by Roquette can help formulators approach mannitol selection more strategically, allowing them to push the limits of their formulations.

Continue reading here

Source: Roquette, website Benefits of mannitol | Roquette Pharma & Consumer Healthcare | Health & Pharma Solutions | Roquette, Darshana Jain (Ghatawat), PhD, Head of Technical Services & Development,Roquette’s Health and Pharma Solutions, Unlocking the benefits of mannitol through the right grade selection

See our next webinar: