Bioavailability oral administration

Absorption/Distribution - Clopidogrel absorption is 50% or more and is rapid after oral administration. Bioavailability is unaffected by food. Both the parent compound and the main metabolite bind reversibly in vitro to plasma protein (98% and 94%, respectively). 

Nitisinone is a reversibile inhibitor of 4-hydroxy-phenylpyruvate oxidase, an enzyme that plays a crucial role in the tyrosine catabolic pathway. Nitisinone prevents the accumulation of the toxic metabolites fumaryl acetoacetate, succinyl acetoacetate and succinyl acetone. Nitisinone is used for the treatment of hereditary tyrosinemia type 1. After oral administration bioavailability is 90% and peak levels are reached at 2.5 hours after dosing. The drug is eliminated mainly in the urine but some CYP3A4-mediated metabolism seems to occur. The elimination half-life is 45 hours. Blood dyscrasias are frequently occurring side effects as are eye problems like conjunctivitis, corneal opacity and keratitis. Exfoliative dermatitis, erythematous rash and pruritus... 

After oral administration bioavailability is low because of extensive metabolism. It... 

Absorption Only 35-70% of oral norfloxacin is absorbed. However, 70-90% of the other fluoroquinolones are absorbed after oral administration. Bioavailability is greatest for ofloxacin and lomefloxacin. Intravenous preparations of ciprofloxacin and ofloxacin are available. Ingestion of the fluoroquinolones with sucralfate, antacids containing aluminum or magnesium, or dietary supplements containing iron or zinc can interfere with the absorption of these antibacterial agents. 

Disposition in the Body. Absorbed after oral administration bioavailability about 40%. The major metabolite is the acetyl derivative, diacetalol, which is active. After an oral dose, about 20 to 40% of the dose is excreted in the urine in 24 hours, about 9 to 12% of the dose as unchanged drug and about 12 to 24% as diacetalol. Up to about 60% of the dose is eliminated in the faeces as unchanged drug and diacetalol. After an intravenous dose, relatively more is excreted in the urine than in the faeces, and the proportion of unchanged drug in the urine is greater than after an oral dose. 

Disposition in the Body. Readily absorbed after oral administration bioavailability about 85%. Up to 85% of a dose is excreted in the urine as unchanged driig in 48 hours, with only 2 to 3% excreted as procainamide and less than 1% as the monodesethyl metabolite. 

Disposition in the Body. Rapidly absorbed after oral administration bioavailability about 90%. The major metabolite, oxypurinol (alloxanthine), is active but less potent than allopurinol. Subjects with a genetic deficiency of xanthine oxidase are unable to metabolise allopurinol to oxypurinol. The excretion of unchanged drug appears to vary with acute or chronic... 

Disposition in the Body. Readily and almost completely absorbed after oral administration bioavailability about 95%. It is metabolised by hydroxylation to give the major metabolite 3 -hydroxyamylobarbitone, which has about one-third of the... 

Disposition in the Body. Almost completely absorbed after oral administration bioavailability about 75%. Extensively meta-... 

Disposition in the Body. Rapidly but incompletely absorbed after oral administration bioavailability about 50%. It is excreted almost entirely as unchanged drug, 35 to 50% of an oral dose being excreted in the urine and 30 to 50% in the faeces, in 24 hours small amounts of 2-hydroxyatenolol and atenolol glucu-ronide are excreted in the urine. 

Disposition in the Body. Rapidly absorbed after oral administration bioavailability almost 100%. Metabolic reactions include V-demethylation and oxidation to uric acid derivatives. About 85% of a dose is excreted in the urine in 48 hours with up to 40% of the dose as 1-methyluric acid, 10 to 15% as 1-methylxanthine and up to 35% as 5-acetylamino-6-formylamino-3-methyluracil and 5-acetylamino-6-amino-3-methyluracil other metabolites excreted in the urine include theophylline, 1,7-dimethylxanthine (paraxanthine), 7-methylxanthine, and 1,3-dimethyluric acid. Less than 10% is excreted in the urine as unchanged drug. The extent of V-acetylation is genetically determined. Caffeine, theophylline, theobromine, and paraxanthine are found in plasma from dietary sources especially coffee, tea and cocoa. An average cup of coffee or tea contains approximately 100 mg of caffeine. 

Disposition in the Body. Readily absorbed after oral administration bioavailability almost 100%. Metabolised by demethylation and subsequent deamination to the active metabolites desme-thylchlordiazepoxide and demoxepam. Demoxepam is further metabolised by hydrolysis with cleavage of the lactam ring and by reduction to desmethyldiazepam (nordazepam) followed by hydroxylation to oxazepam (desmethyldiazepam and oxazepam are also pharmacologically active). About 60% of a dose is excreted in the urine and 10 to 20% is eliminated in the faeces less than 1% of a dose is excreted in the urine unchanged, about 6% is excreted as demoxepam, and the remainder as ring-opened derivatives and glucuronide conjugates of oxazepam and other hydroxylated metabolites. 

Disposition in the Body. Poorly and erratically absorbed after oral administration bioavailability, about 20 to 30% after doses of 250 mg, decreasing with increasing dose. Chlorothiazide is not significantly metabolised and is excreted in the urine to a variable extent depending on the extent of absorption. 

Disposition in the Body. Readily absorbed after oral administration bioavailability about 55%. Flupenthixol decanoate is very slowly absorbed from the site of intramuscular injection. Peak plasma concentrations are attained about 3 to 6 hours after oral administration and 3 to 7 days after intramuscular injection. The main metabolic reactions are sulphoxidation, side-chain N-dealkylation and glucuronic acid conjugation. AT-Desalkylflupen-thixol and flupenthixol sulphoxide are the major metabolites found in plasma (both are inactive). Numerous metabolites are excreted in the urine and faeces and there is evidence of enterohepatic circulation. 

Disposition in the Body. Incompletely absorbed after oral administration bioavailability about 20%. Up to about 25% of an oral dose is excreted in the urine in 24 hours as unchanged drug and two metabolites, guanethidine A-oxide and 2-(6-carboxyhexylamino)ethylguanidine the proportion of metabolites to unchanged drug is variable. A total of about 40% of an... 

Disposition in the Body. Readily absorbed after oral administration bioavailability about 65%. Haloperidol is localised in the tissues and rapidly taken up by the brain. It is slowly excreted in the urine, about 40% of a dose being eliminated in 5 days with only about 1% of the dose as unchanged drug about 15% of a dose is excreted in the bile. Metabolites which have been identified in urine are 4-fluorobenzoylpropionic acid and 4-fluorophenylaceturic acid (the glycine conjugate of 4-fluoro-phenylacetic acid), both of which are inactive. Haloperidol is also metabolised by reduction of the ketone group to a secondary alcohol. 

Disposition in the Body. Readily and almost completely absorbed after oral administration bioavailability 2 to 19% (mean 9) due to extensive first-pass metabolism. Rapidly absorbed after intramuscular or rectal administration. It is excreted rapidly in the urine, mainly as the glucuronide conjugate, with less than 5% of a dose as unchanged drug, and about 5 to 10% as 7-oxomeptazinol. Both metabolites are inactive. Over 50% of a dose is excreted in the urine in 9 hours and over 60% in 24 hours. Less than 10% of an oral dose is eliminated in the faeces. 

Disposition in the Body. Incompletely absorbed after oral administration bioavailability about 70%. Metabolised by N-demethylation to the active metabolite, phenobarbitone, and by p-hydroxylation. Over a period of 10 days, less than 2% of a dose is excreted in the urine as unchanged drug, about 30 to 35% is excreted as p-hydroxymethylphenobarbitone both free and conjugated, and up to 10% may be excreted as phenobarbitone. Small amounts of p-hydroxyphenobarbitone, 5-ethyl-5-(4-hy-droxy-3-methoxyphenyl)barbituric acid, and 5-ethyl-5-(4-hy-droxy-3-methoxyphenyl)-l-niethylbarbituric acid have also been detected in the urine. 

Disposition in the Body. Well absorbed after oral administration bioavailability about 50% due to extensive first-pass metabolism. About 95% of a dose is excreted in the urine within 48 hours, with about 65% of the dose as the inactive metabolite, 4-(2-hydroxy-3-isopropylaminopropoxy)phenylacetic acid, and about 10% as a further inactive metabolite, 2-hydroxy-3-[4-(2-meth-oxyethyl)phenoxy]propionic acid. Two active metabolites, a-hydroxymetoprolol and O-desmethylmetoprolol are also excreted in the urine in amounts equivalent to about 10% and less than 1% of the dose, respectively. Up to about 10% of a dose is excreted as unchanged drug. 

Disposition in the Body. Readily absorbed after oral administration bioavailability 80 to 90%. It is extensively metabolised the major metabolites are the 4 -hydroxy and 2 -hydroxymethyl derivatives, which may be further metabolised by deamination to the corresponding alcohols. The rate and extent of renal excretion is dependent on the urinary pH. Under normal conditions, up to about 20% of a dose may be excreted in the urine as unchanged drug in 24 hours, but this may be increased to about 50% if the urinary pH is maintained at about 5. 

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