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Effervescent Granulation
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
Lubricant substances, known as suitable for effervescent manufacturing, are sodium benzoate, sodium acetate, l-leucine, and carbowax 4000. Combinations of lubricants have also become a possibility. Literature reports calcium and potassium sorbates and micronized polyethylene glycol (PEG) with calcium ascorbate or trisodium citrate [29]. Spray-dried l-leucine and PEG 6000 are also considered as a successful mix [30]. Other lesser soluble lubricants are still however used in formulating effervescent tablets. In any case for good lubrication, a balance should be found between compression efficiency and water solubility. Magnesium stearate is commercially available in combination with sodium lauryl sulfate, a surfactant agent that helps in dispersion [31].
Thermal Analysis
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
The addition of magnesium stearate to the two components already present also showed no interaction (thermogram 3). Pure magnesium stearate gives a melting endotherm at 125°C, and an endotherm at this temperature is just barely discernible in the mixture. It is small because of its low concentration in the mixture.
Physicochemical properties of respiratory particles and formulations
Published in Anthony J. Hickey, Heidi M. Mansour, Inhalation Aerosols, 2019
An “ideal” adhesive mixture would have both cohesive and adhesive interactions reduced to a minimum. Such a task can be accomplished using either a coating with material of low adhesion or a coating reducing the particle contact area, or both. Magnesium stearate, a very common hydrophobic lubricant for oral dosage forms, has been tried extensively for adhesive respiratory blends, typically in concentrations 0.5%–3% w/w. Uniform coatings have been reported for lactose carriers as well as micronized drugs utilizing different high-energy shear mixing (64). Such intensive mechanical treatment also changes the particle surface morphology and possibly the particle size distribution, which need to be taken into account. Significant improvement of powder dispersability has been reported for coated materials in several studies (FPF about 50%) (64), presumably by reduction of adhesion and also moisture uptake by such coated powders. Other excipients tried as force-controlled agents in blends include leucine and lecithin, which are known for their surface-active properties. Although coatings can improve such formulations, the safety of the hydrophobic excipients (e.g., magnesium stearate) for use in the lungs has yet to be established at the concentrations used for dry powder formulations because their clearance mechanisms from the lungs are not well understood. More about different surface-active agents suitable for inhalable engineered particles will be discussed in the next section.
A novel approach of external lubrication in a rotary tablet press using electrostatics
Published in Drug Development and Industrial Pharmacy, 2022
Maren Zimmermann, Felix Michel, Jens Bartsch, Markus Thommes
In addition to the total charge accumulation on the particle surfaces, a slow particle discharging process is crucial for implementing an external lubrication system using electrically charged powder. In contrast to stearic acid and PEG 6000, the discharging process of magnesium stearate was slower and, consequently, the charge on the surfaces of the particles was stable (Table 4). It might be explainable with the different chemical structure of magnesium stearate, which stabilized the negative charges, as they were slowly transferred into the powder bulk or the environment. Additionally, the electrical resistivity of stearic acid was lower compared to magnesium stearate. Therefore, the discharging process for stearic acid was also significantly (α = 0.05) faster. The half-life of the accumulated charge on PEG 6000 particles was even shorter than on stearic acid. The charge could not be stabilized due to the chemical structure. Furthermore, the low electrical resistivity of PEG 6000 facilitated the rapid discharge.
Residence time and mixing capacity of a rotary tablet press feed frame
Published in Drug Development and Industrial Pharmacy, 2021
Maren Zimmermann, Markus Thommes
In Figure 7, the contact angle γ between tablet surface and water as a function of powder residence time is presented; a higher residence time resulted in a higher γ until saturation was reached. A high value of γ indicated a hydrophobic tablet surface caused by magnesium stearate used as lubricant. Magnesium stearate is shear sensitive. Powder particle surfaces were coated by the lubricant due to shearing by the feed frame paddles leading to a higher hydrophobicity and an estimated lower tensile strength. A higher hydrophobicity can cause an elongation of dissolution, while an increased friability and tablet breakage can be the result of a lower tensile strength. The curve trends were similar for all applied rotational speeds. Only a slight impact of paddle speed can be noted, though shear forces were increased with a higher paddle speed. This may be due to the round paddle geometry.
A review of twin screw wet granulation mechanisms in relation to granule attributes
Published in Drug Development and Industrial Pharmacy, 2021
Yi Zhang, Tongzhou Liu, Shahab Kashani-Rahimi, Feng Zhang
Compared to solid–liquid mixing, solid–solid mixing has received less attention in TSWG because materials are typically pre-blended. Prior studies have reported the segregation of hydrophilic and hydrophobic powders due to preferential wetting of the hydrophilic powder in the wetting zone [38,46]. The mixing of the segregated powder (60% hydrochlorothiazide) and the hydrophilic excipients in the kneading zone resulted in homogenous granules [38]. By contrast, in a model composed of 20% magnesium stearate and 80% lactose monohydrate, the mixing in the kneading zone could not prevent segregation [46]. Compared to hydrochlorothiazide (logP: −0.07), magnesium stearate (logP: 7.15) has a much higher hydrophobicity, which compromised the final uniformity of the granules consisting of magnesium stearate and lactose monohydrate [47,48]. Most APIs are much less hydrophobic than magnesium stearate. Thus, particle segregation is not a concern in TSWG for hydrophilic and moderately hydrophobic APIs.