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Physics of Radiation Biology
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
The effective half-life includes both the physical half-life and the biological half-life (time to reduce the radioactivity in the body or in the organ to one half)
Tin and the Lymphatic System
Published in Nate F. Cardarelli, Tin as a Vital Nutrient:, 2019
It should be emphasized that the above experiments used oral dosing, which is an exceptional route. Almost all the published reports describe experiments using other modes of administration, mainly, i.v., i.m., or i.p. injection. Injected tin has an affinity for tumors25 and retards their growth.38 Biological half-life is somewhat longer,39 and accumulation is noted in the liver, at least with inorganic tin.40 Many organs show little or no tin content when administration is s.c.41 Very high blood tin levels are noted 24 hr after i.v. administration.42
Pharmacotherapy
Published in G. Michael Steelman, Eric C. Westman, Obesity, 2016
Dose —The normal starting dose of phentermine HCl for adults is 15 to 18.75 mg (half of a 37.5 mg tablet) once or twice daily, with the second dose before 3 p.m. if a second dose is needed. Although the drug has a biological half-life of 18 to 24 hours and once-daily dosing should be efficacious, some patients benefit from twice-daily dosing. Phentermine has stimulant effects, which typically are mild and fade quickly. In patients who have a history of overreacting to stimulants, or have panic or anxiety, a lower starting dose of 15 mg may be advisable. An even lower starting dose could be achieved by breaking the 37.5 mg tablet into quarters to achieve a dose of approximately 9 mg. Eight-milligram tablets, available before the phen-fen crisis in 1997, are no longer manufactured. The starting dose for younger adolescents should be either approximately 9 or 15 mg per day. Later in treatment, doses may be adjusted as discussed in the following section. One early study reported that patients given phentermine on an alternating month schedule had the same overall weight loss as patients given phentermine continuously (39). This practice is not recommended since it interrupts weight loss, sometimes with significant weight gain during the off months. Patients taken off phentermine often begin to gain in the first month, become discouraged and disillusioned with their treatment, and are thus lost to follow-up.
Vitamin D: sources, physiological role, biokinetics, deficiency, therapeutic use, toxicity, and overview of analytical methods for detection of vitamin D and its metabolites
Published in Critical Reviews in Clinical Laboratory Sciences, 2022
Jiří Janoušek, Veronika Pilařová, Kateřina Macáková, Anderson Nomura, Jéssica Veiga-Matos, Diana Dias da Silva, Fernando Remião, Luciano Saso, Kateřina Malá-Ládová, Josef Malý, Lucie Nováková, Přemysl Mladěnka
Interestingly, most of the vitamin D, either taken orally or synthesized in the skin, fails to become 25(OH)D. Animal data showed that three-quarters of the vitamin D dose taken orally is not used for 25(OH)D synthesis [96]. A small fraction of unmetabolized vitamin D is stored in adipose tissue and muscles. Less than 5% of vitamin D synthesized in the skin was subsequently found in fat tissue in shaven mice, and the biggest portion of vitamin D entering circulation appeared to be excreted into the bile [97]. The half-life of unmetabolized vitamin D in circulation is 2 days [28]. However, in healthy individuals, the biological half-life is much longer. Even with no supply, vitamin D3 can be continuously released from storage tissues for a period of 2–3 months [98]. A plasma half-life of 25(OH)D is about 2 weeks [99]. But again, the biological half-life is much longer due to synthesis from vitamin D3 stored in the body. The biological half-life of the active form, calcitriol, is 12 h [28].
Surgical Management of Haemophilic Pseudotumors: Experience in a Developing Country
Published in Journal of Investigative Surgery, 2019
Yu He, Xi Zhou, Haomin Cui, Guixing Qiu, Xisheng Weng, Baozhong Zhang, Yong Liu
Without inhibitor, a pharmacokinetic evaluation was performed to determine the suitable requirements for perioperative factor replacement, and to achieve therapeutic effect partly. Before evaluation, factors were not administered for at least 48 hr. We suggested that an initial factor infusion bolus of 40-50 IU/kg was used. The factor activity (F:C) and activated partial thromboplastin time (APTT) were examined immediately, and at 1 hr, 3 hr, 6 hr, 8 hr, 12 hr, and 24 hr after infusion. The biological half-life (T1/2) of factor that determined the frequency of administration was estimated by concentration–time curve. To calculate the bolus dose and anticipate the patient's response to factors, the clinician must know the degree to which the plasma factor level will increase in terms of units per kilogram of body weight after intravenous infusion. Combining these results with the APTT allows for formulation of a perioperative scheme. Generally, the bolus dose calculated was intended to raise the circulating factor level to 80% at surgery and postoperative first day, 60% at postoperative 2–3 days, 50% at postoperative 4–7 days, and 30% at postoperative 8–14 days. The APTT should be reduced to 50 s or less during surgery. If surgery lasted longer than 6 hr or uncontrolled intraoperative bleeding occurred, an additional bolus of coagulation factor was given.
Innovative topical niosomal gel formulation containing diclofenac sodium (niofenac)
Published in Journal of Drug Targeting, 2022
Jafar Akbari, Majid Saeedi, Katayoun Morteza-Semnani, Seyyed Mohammad Hassan Hashemi, Amirhossein Babaei, Mohammad Eghbali, Mahsa Mohammadi, Seyyed Sohrab Rostamkalaei, Kofi Asare-Addo, Ali Nokhodchi
Diclofenac sodium (DS), known as a potent NSAID with pronounced analgesic properties, has been so far utilised in the prolonged treatments of osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis. The drug is considerably metabolised in the liver and has to be administered frequently since its biological half-life is only 1 to 2 h [4]. Gastrointestinal consequences such as ulcer, bleeding, or perforation of the intestinal walls have thus been reported with the long term use of DS [5]. Because of its shorter biological half-life as well as adverse effects, it is considered as a perfect candidate for controlled transdermal drug delivery [6–8].