Tetracycline absorption in elderly patients with achlorhydria

Abstract

Five elderly achlorhydric patients and five controls took 250 mg tetracycline as a capsule or as an oral solution. Venous blood samples drawn during the 12-hr period following administration and urine collected for 72 hr post-dosing were assayed fluorometrically for tetracycline. There were no differences between the two groups in either rate or extent of tetracycline absorption. The mean apparent first-order rate constant (ka) for absorption of drug from capsules was 0.58 +/- 0.17 hr-1 for patients and 0.65 +/- 0.21 hr-1 for controls. The mean extent of absorption for capsule dosage forms relative to an oral solution was 1.0 +/- 0.20 for patients and 1.0 +/- 0.24 for controls. Concurrent administration of 2 gm of sodium bicarbonate to 2 of the normal subjects resulted in no impairment of either the rate or extent of tetracycline absorption from capsules, suggesting that the effect of elevated gastric pH on tetracycline bioavailability may relate to formulation.

An improved extraction procedure for the liquid chromatographic determination of propranolol and 4‐hydroxypropranolol in plasma [letter]

“…We measured gastric pH directly and showed that prompt neutralization with sodium bicarbonate did not alter tetracycline absorption, a finding which is in agreement with Kramer, Chapron, Benson & Merch (1978). Therefore, we conclude that the major cause of interaction between acid suppressing drugs and tetracycline is chelation and not increased gastric pH.…”

Tetracyclines inhibit microglial activation and are neuroprotective in global brain ischemia

“…Semisynthetic, the so-called longacting second-generation tetracyclines, doxycycline and minocycline, are absorbed rapidly and completely even in aged population (2)(3)(4)(5) and have a superior tissue penetration into the brain and cerebrospinal fluid (1,6). During recent years, doxycycline and minocycline have been shown to exert biological effects that are completely separate and distinct from their antimicrobial action.…”

Minocycline: far beyond an antibiotic

“…It retains the efficacy against both grampositive and gram-negative bacteria and has been approved by the Medicines and Healthcare Products Regulatory Agency for the treatment of acne vulgaris, and by the US Food and Drug Administration (FDA) for the treatment of some sexually transmitted diseases and rheumatoid arthritis (Good and Hussey, 2003;Blum et al, 2004). Minocycline shows a better pharmacokinetic profile than the first-generation tetracyclines when used orally, being rapidly and completely absorbed, even in elderly populations, with a longer half-life and excellent tissue penetration, and an almost complete bioavailability (Barza et al, 1975;Kramer et al, 1978;Klein and Cunha, 1995). In addition, it is a highly lipophilic molecule that can easily pass through the blood-brain barrier (Brogden et al, 1975), thus promoting its accumulation in cells of the CSF and CNS (Aronson, 1980;Yrjänheikki et al, 1999;Kielian et al, 2007) and enabling its use in the treatment of many CNS diseases (Saivin and Houin, 1988;Wang et al, 2003;Yong et al, 2004).…”