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Brachytherapy Treatment Planning
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Margaret Bidmead, Dorothy Ingham, Peter Bownes, Chris D. Lee
There was the possibility of optimising the dose distribution and tailoring it to individual patients using the LDR Selectron. Compared with external-beam treatment, there are relatively few options for altering dose distributions in intracavitary therapy. However, some modification of the dose distribution to tailor it to the individual patient anatomy could be achieved by varying the number of active pellets and their position in each applicator. For example, if the dose to the rectum was too high, the ovoid sources could be moved from position 3 to position 4, 5, 6 or 7 (or removed completely), which results in a shift in the isodose curves. Because of the high dose gradients, the dose to the anterior rectal wall could be altered sufficiently by this change whilst making very little difference to the dose higher in the pelvis. However, the dose to the bladder might be increased unacceptably.
Extrusion/Spheronization as a Granulation Technique
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
As pharmaceutical dosage units, pellets are defined as small, free-flowing, spherical or semi-spherical particles made up of fine powders or granules of bulk drugs and excipients by a variety of processes, extrusion-spheronization being one. The major advantage of extrusion/spheronization over other methods of producing drug-loaded spheres, pellets, or granules is the ability to incorporate high levels of active components without producing excessively large particles. This is critical to the production of pharmaceutically acceptable free-flowing spherical granules, as well as the pellets used for the more typical applications. Heilman et al. showed that pellets having a drug loading level of 80% can be produced reproducibly [8].
An Introduction to Two-Piece Hard Capsules and Their Marketing Benefits
Published in Larry L. Augsburger, Stephen W. Hoag, Pharmaceutical Dosage Forms, 2017
Pellets are an excellent tool for numerous applications. Pellets can be coated with sustained-release and enteric film coatings to achieve unique release profiles, or multiple release rates in a single dosage unit by mixing pellets having different film coatings. Pellets also offer the ability to mix multiple active ingredients or incompatible active ingredients.
Applicability of image analysis to support QbD driven development of pellets
Published in Drug Development and Industrial Pharmacy, 2021
Nemanja Aničić, Polona Smrdel, Domen Kitak, Teo Morožin, Miha Jaklič, Peter Usenik, Sara Vidovič
Pellets have significant benefits over single unit dosage forms: they are less susceptible to dose dumping; their passage through the gastrointestinal tract (GIT) is less influenced by the nutritional state and gastric emptying, leading to more consistent drug release; there is a lower incidence of gastrointestinal irritation due to decreased local irritation of the active pharmaceutical ingredient (API) in the GIT; they have the ability to deploy multiple coatings with a variety of functions (masking the taste, gastro-resistance, mucoadhesion, controlled release, etc.); and adding multiple API layers that allow chemically incompatible API’s to be contained in a single dosage form. Other significant advantages are convenient multiple dose production, their suitability for low or high dose dosage forms, good flowability, suitability for filling capsules or producing multi-particulate tablets [1–4]. All these characteristics emphasize the high potential of coated pellets in the future development of personalized medicines as they offer flexibility in dosage form design as well as improved safety and efficacy of the medicines [5].
An update on the available and emerging pharmacotherapy for adults with testosterone deficiency available in the USA
Published in Expert Opinion on Pharmacotherapy, 2021
Eliyahu Kresch, Mehul Patel, Thiago Fernandes Negris Lima, Ranjith Ramasamy
The earliest form of testosterone replacement comes in the form of long-acting subcutaneous pellets made of crystalline testosterone formulated to allow for a slow release within extracellular fluid [53]. Implantation requires an in-office procedure under local anesthetic in which a small incision is made on the hip (or another fatty area) and the pellets are placed with the aid of a trocar. The recommended starting dose is 150–450 mg every 3–6 months. Dosage adjustments are made depending on the patient’s response and the appearance of adverse events [54]. Despite these recommendations, clinical studies and experience over the years have demonstrated that more pellets are needed to achieve satisfactory results [55]. Pharmacokinetic studies have been performed using 100 mg or 200 mg pellets at 600 mg doses (6 ×100 mg or 3 × 200 mg) and 1200 mg (6 × 200 mg). Testosterone levels were maintained at physiological levels for 4–5 months with 600 mg and 6 months in the 1200 mg group with a half-life duration of 2.5 months [56].
Losartan potassium sustained release pellets with improved in vitro and in vivo performance
Published in Pharmaceutical Development and Technology, 2020
Nuha I. Abou Obaid, Fahad I. Al-Jenoobi, Mohamed A. Ibrahim, Mohd A. Alam
Multiple unit dosage forms have gained considerable popularity for controlled release technology over conventional single units. Among the various types of multiple-unit dosage forms, the interest in pellets has been increasing continuously due to their unique clinical and technical advantages. Pellets are defined as spherical, free-flowing granules with a narrow size distribution, typically varying between 500 and 1500 μm for pharmaceutical applications (Ibrahim and Shazly 2014). Pellets disperse freely in the GIT because of their small size and large surface area of absorption thus, they improve drug absorption, reduce peak plasma fluctuations, and minimize potential side effects without lowering drug bioavailability (Mehta et al. 2001). In addition to therapeutic advantages, formulation advantages that can be gained with pellets include better flow properties, less friable dosage form which ensure uniform drug content with minimum risk of dose dumping, narrow particle size distribution and ease of coating (Kushare et al. 2011). Extrusion and spheronization is currently one of the techniques that is concurrently used in the production and development of drug-loaded pellets. Pellets with specific attributes could be obtained by monitoring the pellet composition and the extrusion/spheronization conditions. The preparation of spherical granules or pellets using extrusion–spheronization is now a more established technique because of its advantages over the other conventional pellet manufacturing techniques (Patel et al. 2018).