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Formulation Development of Small-Volume Parenteral Products
Published in Sandeep Nema, John D. Ludwig, Parenteral Medications, 2019
Madhav S. Kamat, Patrick P. DeLuca
Examples of drugs marketed in water-miscible systems include digoxin, phenytoin, diazepam, and others as shown in Table 10.5 [44,45]. These injections are formulated in a water-miscible system containing glycols and alcohol and adjusted to a suitable pH. Other co-solvents used in the past included glycerin in deslanoside, dimethylacetamide in reserpine, and DMSO in chemotherapeutic agents undergoing clinical testing. PG is used most frequently as a cosolvent, generally in concentrations of 40%. Although such systems are stable in individual vials, care must be exercised upon administration. For example, phenytoin is dissolved as the sodium salt in a vehicle containing 40% PG and 10% ethanol and adjusted to a pH of 12 with sodium hydroxide. However, if this solution is added to a large-volume intravenous solution and the pH is lowered to a value close to the pKa of the drug (pKa = 8.3), precipitation of the drug can occur. This is due to the fact that in aqueous systems at pH below 11, the amount of undissociated phenytoin exceeds its solubility.
Therapeutical potential of metal complexes of quinoxaline derivatives: a review
Published in Journal of Coordination Chemistry, 2022
Chrisant William Kayogolo, Maheswara Rao Vegi, Bajarang Bali Lal Srivastava, Mtabazi Geofrey Sahini
Budagumpi et al. [74] reported the synthesis of an oligoquinoxaline derivative with a phthalazine core by condensing 1,4-dihydrazinophthalazine with 2,3-dichloroquinoxaline as an ‘‘end-off’’ compartmental ligand that was complexed to Co(II), Ni(II), Cu(II), and Zn(II) (Figure 42). The anticonvulsant activities for the prepared compounds were evaluated against Wistar rats by the maximal electroshock method. H2L (128), Co(II) (129a), and Ni(II) (129b) complexes demonstrated considerable suppression of electroshock-induced seizures. Compounds 129c and 130 were not active. The active compounds acted in the same way as the standard drug, phenytoin, which suppresses seizures by direct stabilization of the membrane normally through acting on fast sodium ion channels. The electrochemical behavior of 128 and its metal complexes revealed only the ligand to be redox-active. The ligand displayed three oxidation peaks that were assigned to the loss of H+, while the reverse scan indicated three reduction peaks assigned to regaining lost protons. The redox behavior of the ligand was finally considered to be a process that involves the transfer of two-electron and two protons [74].