Folke Rasmussen

Plasma digoxin after parenteral administration Local reaction after intramuscular injection

Concentrations of digoxin in plasma after intravenous or intramuscular administration were measured in 8 sub;ects. Two hours after intramuscular in;ection concentrations were higher than after intravenous in;ection. A similar difference between the concentrations of digoxin in plasma was observed after intravenous and intramuscular administration to pigs. The shape of the curves was also similar to that of curves in man. Postmortem examination of the iniection sites in pigs revealed large necrotic areas after intramuscular in;ection of digoxin. The size of the necrotic area increased with the volume iniected. Necrotic areas were also demonstrated after intramuscular in;ection of the vehicle without digoxin, but they were smaller.

Relationships between molecular structure and excretion of drugs

Abstract Drugs and their metabolites are usually eliminated from the body by excretion in the urine or bile or sometimes both, but other pathways may be used, such as milk, saliva, sweat or the expired air. The excretion can take place by passive or by active processes, and is influenced by the physico-chemical properties of the drug.

Metabolism of sulfadiazine in neonatal and young pigs: Comparative in vivo and in vitro studies

Metabolism of sulfadiazine (SDZ) was studied in vivo and in vitro during postnatal development of piglets in order to examine whether in vitro metabolism approaches the in vivo situation. Experiments were performed in 1-day-, 8-day- and 60-day-old piglets. In vivo: 14C-SDZ was injected intravenously and urine and tissue samples collected after 3 hr. Urinary excretion data as well as data from liver and kidney tissue indicated a relatively high capacity for acetylation at birth, while the capacity for oxidation is low during the first week of life. At 60 days of age the acetylation and oxidation of SDZ is equal each accounting for about 20% of the amount excreted in urine. In vitro: Incubation of subcellular fractions of liver and kidney showed that acetylation of SDZ in liver reached maximum within 1 week. Oxidative activity was absent at 1 day, present at a low level at day 8, and at a high level at day 60. Neither acetylation nor oxidation of SDZ took place in kidney. The results show a close correlation between in vivo and in vitro results with respect to the developmental pattern seen in piglets during the postnatal period of life.

Renal clearance: Species differences and similarities

Species differences and differences between newborn and adults in glomerular filtration rate (GFR), active tubular secretion and back-diffusion in the kidney are described. Measuring the renal clearance of drugs — organic acids or organic bases — and relating this clearance to the GFR, the processes involved in the renal handling of a drug are described. The main principles involved in the renal handling of drugs are the same in the various, animal species and age-groups, but the quantitative influence of these processes may vary considerably from one animal species to another and from neonates to adults.