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Cardiovascular Medications in Pregnancy
Published in Afshan B. Hameed, Diana S. Wolfe, Cardio-Obstetrics, 2020
All medications can enter breast milk, but how readily the drug passes into mature milk depends on several factors including: Drug molecular weightLipid solubilityProtein bindingVolume of distributionHalf-lifeAcid dissociation constant (pKa)
Local Anesthetics and Additives
Published in Bernard J. Dalens, Jean-Pierre Monnet, Yves Harmand, Pediatric Regional Anesthesia, 2019
Jean-Pierre Haberer, Bernard Jacques Dalens
Due to their amine portion, most local anesthetics are weak bases. In aqueous solutions, there is an equilibrium between the nonionized (free base) and ionized (cationic) forms.1,2 The degree of ionization depends upon the dissociation constant (Ka) of the conjugate acid, and upon the local hydrogen ion (H+) concentration. The ionization of a substance is usually evaluated by the pKa, which is the negative logarithm of the acid dissociation constant (Ka) and which represents the pH value at which the molecule is 50% ionized.
Physiology of the respiratory system
Published in Louis-Philippe Boulet, Applied Respiratory Pathophysiology, 2017
Hasselbalch modified this first equation using a logarithmic transformation: where pK is the logarithmic reciprocal of the carbonic acid dissociation constant. For practical purposes, it is difficult to measure very small concentrations of [H2CO3]. Therefore we substitute the concentration of dissolved CO2 for [H2CO3] to obtain the modified Henderson–Hasselbalch equation.
Updates on Enhanced Recovery after Surgery protocols for plastic surgery of the breast and future directions
Published in Baylor University Medical Center Proceedings, 2023
Nicholas F. Lombana, Ishan M. Mehta, Caiwei Zheng, Reuben A. Falola, Andrew M. Altman, Michel H. Saint-Cyr
The pharmacokinetics of such drugs is further influenced by the acid dissociation constant, pKa, lipid solubility, and protein binding of each agent.14 Agents with a pKa closer to body acidity, pH 7.4, have a faster onset of action, secondary to ease of passage across the nerve cell membrane.14 The choice of local anesthetic agent is dependent on several factors including patient allergies, desired duration of action, and desired onset. For example, lidocaine has been shown to provide anesthesia for 1 to 3 hours and bupivacaine for up to 10 hours.14,15 It is particularly important to be cognizant of local anesthetic agent dosing to prevent local anesthetic toxicity. The reported maximum dose for lidocaine with epinephrine is 7 mg/kg; for lidocaine without epinephrine, 4.5 mg/kg; and for bupivacaine (with or without epinephrine), 2 to 3 mg/kg.14,15
Development of a lower-sodium oxybate formulation for the treatment of patients with narcolepsy and idiopathic hypersomnia
Published in Expert Opinion on Drug Discovery, 2022
Gunjan Junnarkar, Clark Allphin, Judi Profant, Teresa L. Steininger, Cuiping Chen, Katie Zomorodi, Roman Skowronski, Jed Black
After preclinical testing of several formulations, two initial mixed-cations candidates were identified and explored further: JZP-507 and LXB. JZP-507 contains 50% less sodium than SXB, whereas LXB contains 92% less sodium than SXB. A phase 1 healthy volunteer PK study demonstrated that JZP-507 was bioequivalent to SXB. In another phase 1 PK study in healthy volunteers, LXB was found to be bioequivalent for oxybate plasma AUC but non-bioequivalent for oxybate plasma Cmax (which was lower with LXB compared with SXB). The decision to move forward with LXB, the non-bioequivalent formulation, was based upon the greater reduction in sodium, which would better serve patients’ needs (Table 2; Figure 3). The total concentration of calcium, magnesium, potassium, and sodium oxybates in LXB oral solution is 0.5 g/mL, equivalent to 0.413 g/mL of oxybate. LXB has a solution pH range of 7.3–9.0 and an acid dissociation constant (pKa) of 4.47. Cation amounts of 34.3 mEq calcium, 15.0 mEq magnesium, 16.4 mEq potassium, and 5.7 mEq sodium are present in the volume of solution delivering 9 g of LXB.
Advances in the use of cell penetrating peptides for respiratory drug delivery
Published in Expert Opinion on Drug Delivery, 2020
Larissa Gomes dos Reis, Daniela Traini
Most of the cationic CPPs are characterized by the presence of arginine and lysine residues in their composition. The high equilibrium acid dissociation constant (pKa values) of the side chains of these amino acids of ~13.8 and 10.4, respectively, leads to a protonated state at pH 6.8–7.0 [20], making them cationic. The number of arginine and lysine residues in the peptide composition has been directly correlated to their internalization capabilities, with higher efficiency associated with arginine-containing peptides compared to lysine residues [18,21]. This greater efficiency can also be related to the higher pKa of arginine guanidinium group, that was shown to be still protonated when buried in a hydrophobic microenvironment like a protein or the lipid membrane [20]. This protonation effect could explain the differences between poly-arginine and poly-lysine peptides, and the better efficiency observed for arginine-containing CPPs in promoting endosomal escape [21].