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Bioavailability and Granule Properties
Published in Dilip M. Parikh, Handbook of Pharmaceutical Granulation Technology, 2021
The subject of bioavailability began to receive growing attention as studies showed that the therapeutic effectiveness of a drug from the dosage form depends, to a large extent, on the physiological availability of their active ingredient(s) and is a function of the drug concentration in the patient's blood or plasma. The importance of bioavailability in drug therapy, therefore, stems from the fact that the rate and extent of absorption of a drug from a dosage form can affect the patient's response to a drug. In light of these facts, the determination of bioavailability has become one of the ways to assess the in vivo performance of a dosage form following its formulation development. It must, however, be remembered that bioavailability studies, very often, are conducted in normal, fasted, and a small number of subjects, and therefore, the results of these studies may not always reflect the true efficacy relationship in patients under treatment conditions. For many years, it was assumed that if a dosage form contained the labeled amount of a drug, its performance could be taken for granted. However, it is now evident for some time that many factors acting individually or in concert may produce therapeutic failure.
Emerging Oral Treatments: Oral Minoxidil for Androgenetic Alopecia
Published in Rubina Alves, Ramon Grimalt, Techniques in the Evaluation and Management of Hair Diseases, 2021
Jared Marc John, Rodney Sinclair
Oral minoxidil undergoes extensive first-pass glucuronidation before it reaches systemic circulation [18]. Sublingual administration bypasses hepatic metabolism, thereby increasing bioavailability compared to oral administration. A case series evaluating the efficacy and safety of low-dose sublingual minoxidil (0.45–0.9 mg) in 64 MPHL and FPHL patients over 12 months reported an improvement in hair density and reduction in shedding with lower rates of adverse effects compared to previous studies of oral minoxidil [19].
Respiratory, endocrine, cardiac, and renal topics
Published in Evelyne Jacqz-Aigrain, Imti Choonara, Paediatric Clinical Pharmacology, 2021
Evelyne Jacqz-Aigrain, Imti Choonara
The level of lung function in asthma may affect the systemic availability of inhaled corticosteroids. Systemic bioavailability and effects of an inhaled drug are more pronounced in patients with mild asthma than in patients with more severe disease [9]. This is probably due to differences in the deposition pattern caused by a smaller airway diameter in patients with more severe disease.
Mathematical modelling of drug-diffusion from multi-layered capsules/tablets and other drug delivery devices
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Drugs are chemical or biological compounds that affect the human body and its functioning. The drug delivery to the biological tissues through diffusion and absorption occurs when it enters the circulatory system. The level of absorption can affect the speed and amount of the drug and its side of action. This is called bioavailability. If a tablet/capsule or some other drug delivery device (DDD) releases the drug quickly, blood levels may become too high whereas slow release may result in low levels of absorption. Addition of factors affecting bioavailability and absorption of the drugs, include properties of the drug and the physiology of the person, such as pH levels in the stomach and its speed of emptying. Therefore, specific formulations are used to release the drug at a desired speed. Common formulations include capsules, tablets, transdermal patches, solutions and other DDDs (Borchardt et al. 1996). To this end, mathematical modeling of diffusional and release processes provides detailed insights to simulate the biological systems and biomedical phenomena with the aid of computational power (Sidig 2015). To depict the desired release of the drug (from a capsule/tablet or other DDDs), to the targeted biological tissue, mathematical models in drug delivery have played a vital role to design and shape the drug delivery systems (Peppas and Narasimhan 2014).
Covalently coupling doxorubicin to polymeric nanoparticles as potential inhaler therapy: in vitro studies
Published in Pharmaceutical Development and Technology, 2021
Lung offers many advantages through an inhaler delivery system for noninvasive drugs for the treatment of respiratory diseases such as lung cancer. Compared with oral or intravenous injection, it is predicted that the bioavailability of drugs in the lung can be increased by using it as an intrapulmonary carrier, as the lung has limited intracellular and extracellular drug-metabolizing enzyme activity, unlike the gastrointestinal tract and liver. Moreover, the inhaler delivery system also reduces systemic side effects caused by the drugs and serves as the use of a non-invasive ‘needle-free’ delivery system. Furthermore, higher absorption rate, lower drug doses, and rapid onset of action are among the advantages of inhaler administration (Karathanasis et al. 2005; Loira-Pastoriza et al. 2014). Lately, there has been an increasing interest in developing inhalable drug delivery systems (i.e. Wauthoz et al. 2010; Zhang et al. 2018; Kaur et al. 2020) for lung cancer (primary lung cancers and lung metastases) therapy.
Dermato-pharmacokinetic: assessment tools for topically applied dosage forms
Published in Expert Opinion on Drug Delivery, 2021
Vamshi Krishna Rapalli, Gautam Singhvi
The bioavailability of the topical and transdermal administered drugs is affected by various factors. They include permeation through the skin (rate-limiting membrane stratum corneum), physicochemical properties of the drug (pKa, logP, solubility, molecular weight), excipients used in the formulation, type of formulation, presence of enzymes in skin structures, application site, and type of the skin. After the topical or transdermal application of the formulation onto the skin, the drug must permeate deeper layers by crossing various layers. Various permeability enhancement techniques are employed to increase drug transport into the stratum corneum. Consequently, skin cannot be deemed as a single compartment. The estimation of drug retained in skin layers is critical in topical and transdermal drug delivery. Therefore, there is a need to separate the skin into layers to estimate the drug permeation in different layers [1,2].