Pharmacokinetics administration routes

Pharmacokinetics PO route onset 20-60 min, peak N/A, duration 6-8 hr. Well absorbed after PO administration. Widely distributed. Metabolized in liver to active metabolite, a form of phenobarbital. Minimally excreted in urine. Removed by hemodialysis. Half-life 34 hr. 

The pharmacokinetics and residue excretion profiles of differing formulations/administration routes of nortestosterone esters were examined in beef heifers (23). Differences were not found in the pharmacokinetic parameters... 

A -tetrahydrocannabinol is a liquid and is highly insoluble in water (8-10). This can be a critical factor in its bioavailability, pharmacokinetics and pharmacological action. Large differences in the bioavailability of tetrahydrocannabinol from various solutions and administrative routes have been reported (9,10). Evidence has been presented (8) that tetrahydrocannabinol s solubility may be exceeded in plasma, resulting in its possible precipitation and fortuitous localized accumulation in body organs. 

Pharmacokinetics Administration can be by an intravenous, oral, or topical route. The efficacy of topical applications is doubtful. The drug distributes well throughout the body, including the cerebrospinal fluid. Acyclovir is partially metabolized to an inactive product. Excretion into the urine occurs both by glomerular filtration and tubular secretion. Acyclovir accumulates in patients with renal failure. 

Clinical trials are studies to evaluate the effectiveness, pharmacokinetics, and safety of medications or medical devices by monitoring their effects on large groups of people. Clinical research trials may be conducted by government health agencies, researchers affiliated with a hospital or university, independent researchers, or private industry. The use of an approved medicinal product in nonapproved conditions (different administration route, dose, clinical indications, etc.) requires also a new clinical trial. 

In this section, the pharmacokinetics of clinically important peptide/protein drugs, such as insulin, EPO, G-CSF, interferon, growth hormone, leuprolide, desmopressin, and antibodies, are described in relation to their administration routes and formulations (i.e., dosage forms). 

Usually, desmopressin is administered intranasally by use of sprays or drops. This administration route of desmopressin was considered to be more efficacious than the oral route, because bypassing the gastrointestinal tract increases the absolute bioavailability from less than 1% to approximately 5%. However, nasal application of desmopressin is accompanied by high intersubject and intrasubject variability in plasma pharmacokinetics [215]. Therefore, there have been several pharmaceutical research efforts to improve nasal delivery of desmopressin. 

The most widely used parenteral administration avenues are intravenous (iv), intramuscular (im), and subcutaneous (sc). In addition, there are several minor applications (e.g. intraarterial). Application of a protein drug by the different main parenteral administration routes may have profound effects on the pharmacological performances. When the drug is administered iv, it is immediately available for action in the circulation, while drugs administered im or sc need more time to reach the blood (depot effect), and consequently the pharmacokinetic (PK) profiles could be different. Besides the PK, the route of administration may have influence on the primary distribution of the drug. For example, when administered sc, smaller and hydrophiUic proteins tend to enter the venous system, while larger and/or more hydrophobic proteins tend to... 

Pharmacokinetics - labeling of a potential drug candidate. This study includes distribution studies of drug passage over the blood-brain barrier and selective accumulation in critical organs. Apart from intravenous administration, oral and nasal administration routes are other important applications employed for quantification of the deposition and disposition of a drug formulation. 

The pharmacokinetics of azacitidine shows that it is rapidly absorbed after s.c. administration with the peak plasma concentration occurring after 0.5 h. The bioavailability of s.c. azacitidine relative to i.v. azacitidine is approximately 89%. Urinary excretion is the primary route of elimination of azacitidine and its metabolites. The mean elimination half-lives are about 4 h, regardless of i.v. or s.c. administration. 

Marketing Extension Application (change in active substance, bioavailability, pharmacokinetics, strength, pharmaceutical form or route of administration, if... 

Figure 5,4 Pharmacokinetics. The absorption distribution and fate of drugs in the body. Routes of administration are shown on the left, excretion in the urine and faeces on the right. Drugs taken orally are absorbed from the stomach and intestine and must first pass through the portal circulation and liver where they may be metabolised. In the plasma much drug is bound to protein and only that which is free can pass through the capillaries and into tissue and organs. To cross the blood brain barrier, however, drugs have to be in an unionised lipid-soluble (lipophilic) form. This is also essential for the absorption of drugs from the intestine and their reabsorption in the kidney tubule. See text for further details...

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