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Macrocyclic Receptors for Biomolecules and Biochemical Sensing
Published in Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney, Macrocyclic Receptors for Environmental and Biosensing Applications, 2022
Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney
Synthetic nucleosides analogues are pharmaceutically important molecules that resemble naturally occurring nucleosides. These are largely used as anti-viral agents (Acyclovir), a drug for cancer and rheumatologic diseases (azathioprine, allopurinol) and even bacterial infections (trimethoprim). The chemical modification of three-component of a nucleoside, i.e., purine or pyrimidine bases, five-membered sugar (ribose/deoxyribose) and hydroxymethyl group as a polar group are the key steps for the synthesis of these pharmaceutically active compounds. The interaction of nucleoside analogs with different viral polymerases (DNA polymerases/reverse transcriptase/RNA polymerases) follows different inhibition pathways for viral replication. Acyclovir is an antiviral agent that has been used against herpes simplex and varicella-zoster virus infections.
Pulmonary complications of bone-marrow and stem-cell transplantation
Published in Philippe Camus, Edward C Rosenow, Drug-induced and Iatrogenic Respiratory Disease, 2010
Bekele Afessa, Andrew D Badley, Steve G Peters
HSCT recipients who are seronegative for HSV should avoid exposure to patients with HSV infection. Acyclovir and its derivatives (valacyclovir and famciclovir) are used for the prevention and treatment of HSV infection. Foscarnet is used if resistance to acyclovir exists.
Formulation Development and Optimization of Floating Granules of Acyclovir by Melt Granulation Technique
Published in Particulate Science and Technology, 2015
Ravindra S. Thakare, Sanjay B. Patil
Acyclovir, the first agent to be licensed for the treatment of herpes simplex virus infections, is the most widely used drug for infections such as cutaneous herpes, genital herpes, chicken pox, varicella zoster infections, and herpes keratitis. Acyclovir is currently marketed as capsules (200 mg), tablets (200, 400, and 800 mg), and suspension for oral administration, intravenous injection, and topical ointment. Oral acyclovir is mostly used as 200 mg tablets, five times a day. In addition, long-term administration of acyclovir (6 months or longer) is required in immunocompetent patients with relapsing herpes simplex infection. The presently available conventional therapy is associated with a number of drawbacks such as highly variable absorption and low bioavailability (10–20%) after oral administration. Furthermore, with increase in dose, there was a decrease in bioavailability. Moreover, because the mean plasma half-life of the drug is 2.5 h, five times a day administration is required (O'Brien and Campoli-Richards, 1989; Meadows and Dressman, 1990; JalonDe et al., 2003; Fuertes et al., 2006). In order to make oral therapy of acyclovir for more patients compliant, there is a need to develop sustained drug delivery dosage form. Researchers have investigated formulating acyclovir in delivery systems using different approaches like matrix tablets, microspheres, and polymeric films (Park et al., 1992; Rossi et al., 2003; Dhaliwal et al., 2008). The main problem with the therapeutic effectiveness of acyclovir is its absorption, which is highly variable and dose dependent, thus reducing the bioavailability to 10–20%. Acyclovir is soluble in acidic pH and is predominantly absorbed from upper gastrointestinal tract (GIT) to duodenum to jejunum regions. There are indications of its active absorption from the duodenum and jejunum regions of GIT. In commercially available dosages forms, the amount of drug absorbed is very low (10–20%) due to short residence time of the dosage forms at the absorption site. As a result, most of the drug is excreted in the feces (50–60%) in unabsorbed form.