Absorption and excretion of "Penbritin"

Pharmacology and chemotherapy of ampicillin--a new broad-spectrum penicillin

The pharmacology and chemotherapy of a new penicillin, 6[D(-)-alpha-aminophenylacetamido] penicillanic acid, are described. It is non-toxic, is absorbed orally and is distributed throughout the body in a manner similar to other penicillins. It is eliminated unchanged from the body in high concentrations in the bile and urine. Almost all of the antibiotic can be accounted for in the urine and intestinal contents 2 hr after intramuscular administration but not after oral administration. It is concluded that the antibiotic is not metabolized within the body. Studies with infected animals show that it is as effective as the existing oral penicillins against Staphylococcus pyogenes Smith (penicillin sensitive), Streptococcus pyogenes Group A and Diplococcus pneumoniae. It is ineffective against penicillin-resistant Staphylococci. When tested in mice infected with the gram-negative organisms, Salmonella tryphimurium and Klebsiella pneumoniae, it was considerably more active than tetracycline and chloramphenicol.

ACTIVITY OF AMPICILLIN IN VITRO COMPARED WITH OTHER ANTIBIOTICS

Comparative tests in vitro for antibacterial activity were carried out with ampicillin, tetracycline, and chloramphenicol using 673 clinical isolates of Gram-negative bacilli and Streptococcus faecalis. Further comparative tests were also carried out with ampicillin, chloramphenicol, colistin sulphate, colistin methane sulphonate, cycloserine, kanamycin, nitrofurantoin, polymyxin, streptomycin, and tetracycline, using groups of 20 strains of each of the main species selected at random from the total number of isolates. Of the total number of isolates a higher percentage was inhibited by ampicillin than by tetracycline or chloramphenicol. Ampicillin showed particularly high activity against certain species of bacteria and displayed an antibacterial spectrum not shown by any of the other antibiotics tested.

Pharmacokinetics and tolerance of cefuroxime axetil in volunteers during repeated dosing

A total of 158 volunteers each received 21 repeated oral doses of 500 mg of cefuroxime axetil (CAE) during four comparative cross-over trials. Pharmacokinetics were studied in 8 volunteers (CAE versus ampicillin), relative bioavailability and tolerance were studied in 100 volunteers (CAE versus pivmecillinam and CAE versus pivampicillin), and tolerance alone was studied in 50 volunteers (CAE versus ampicillin). Overall, urinary recoveries of the active antibiotics ranked absorption of the drugs in the order least to greatest: pivmecillinam, ampicillin, CAE, and pivampicillin. The pharmacokinetics of CAE and ampicillin did not change after repeated dosing. Peak serum levels of cefuroxime were significantly higher than those of ampicillin after doses 1 and 21 but the urinary recoveries of both antibiotics were around 35% of the dose. CAE was as well tolerated as ampicillin but there were smaller numbers of episodes of fluid bowel motions on pivmecillinam and pivampicillin than on CAE, which may have been due to the smaller amounts of active antibiotic in the doses of the pivaloyloxymethyl esters.

An open study of pivampicillin (Pondocillin) as a treatment for acute lower urinary tract infection

In a multicentre general practice study 158 females with acute, uncomplicated urinary tract infection received a 5-day course of pivampicillin 500 mg twice-daily (Pondocillin). Significant bacteriological cultures were obtained from forty-one patients before treatment and the original organism was eradicated in thirty-eight of these patients (93%). The mean symptom score was reduced from 7.33 to 1.18. Eleven patients (7%) reported side-effects. One patient ceased treatment after 4 days due to a rash. Pivampicillin, in a convenient twice-daily regimen, was confirmed as an effective treatment for acute lower urinary tract infection.

Intrarenal concentrations of ampicillin in acute pyelonephritis

The intracortical, medullary, and papillary distribution of ampicillin was studied in normal and pyelonephritic rats. At 4 days after induction of pyelonephritis, the animals were given a single injection of 100 mg of ampicillin per kg or were treated for 1 week with two daily doses of 100 mg/kg. Major differences in the intrarenal distribution of ampicillin were noted between normal and pyelonephritic animals. At 2 hours after injection, the concentrations of ampicillin in all parts of the infected kidneys were significantly lower (P less than 0.05) than in normal kidneys. The area under the curve (micrograms.minute per milliliter) over a 4-h period after single injection was much lower in the medulla (6.3 +/- 0.9) and papilla (29.6 +/- 4.2) of infected kidneys than in the medulla (11.2 +/- 1.6) and papilla (44 +/- 10.1) of noninfected kidneys. Whereas the ratio of concentration in tissue to concentration in serum ranged to 11.1 in the papilla of normal animals, this ratio was reduced to 2.4 in the presence of pyelonephritis. The diminution of the concentration gradient was also striking in the urine, where there was a reduction of more than threefold in pyelonephritic animals. One week of therapy resulted in a noticeable reduction of the inflammatory process associated with a return to near-normal intrarenal distribution of ampicillin. In normal rats treated with multiple doses, there were decreases of the antibiotic concentrations in serum and kidneys and in the area under the curve for these tissues.

Dose dependence in human absorption of aminopenicillins

The concentration of antibiotic in a focus of infection depends both on the peak serum concentration and on the area under the serum concentration time curve (AUC). A knowledge of the relationship between increased doses and the corresponding response in serum concentration would be relevant as a basis for determining an adequate clinical dosage. Dose-related changes in the two pharmacokinetic variables, peak serum concentration and AUC, after single doses of bacampicillin are compared with data on different aminopenicillins from other studies. With ampicillin there is a nonlinear relationship between both dose-peak and dose-AUC. The results indicate that the poor absorption of oral ampicillin can only be partially compensated for by increasing the oral dose. But with amoxycillin and the ampicillin esters the absorbed amount (AUC) is a linear function of the dose in the dosage range investigated. The increase in peak serum level with high doses of oral ampicillin is far less than proportional, while this tendency was less pronounced for amoxycillin and still less for pivampicillin, talampicillin and bacampicillin.

Ampicillin penetration into the rabbit eye

Distribution of intravenously injected ampicillin of 50 mg/kg was studied in the rabbit eye using radioactive tracer method. Antibiotic concentration regarded as therapeutic in the treatment of gram-negative organisms was obtained in all vascularized ocular structures. Intermediate values were measured from the cornea and aqueous humour. In the vitreous body and lens, ampicillin was unable to approach a concentration that would be effective against the common gram-negative organisms. The low ampicillin concentration in the vitreous body and lens was unchanged by systemically administered probenecid, which in other parts of the eye caused significantly higher ampicillin levels.

Comparative clinical pharmacology of bacampicillin and high oral doses of ampicillin

Ampicillin is often used in high oral doses due to its incomplete absorption. The objective of this study was to compare the bioavailability of bacampicillin, a new prodrug of ampicillin which is nearly completely absorbed, to that of high doses of oral ampicillin. Single oral doses of bacampicillin 400 mg or 800 mg and ampicillin 500 mg, 1 g, or 2 g were given to 12 male subjects according to a cross-over design after overnight fasting. The median time after administration till the peak serum level was 0.75 and 1.0 hour with bacampicillin 400 mg and 800 mg respectively, as compared to 1.5, 2.0 and 1.5 hours for the ampicillin doses. The mean of the individual peak serum level after bacampicillin 400 mg, was 7.7 mg/l, which is higher than that after ampicillin 500 mg, 5.2 mg/l, and about the same as that after ampicillin 1 g, 7.6 mg/l. A slightly higher mean peak level was seen after bacampicillin 800 mg, 12.2 mg/l, as compared to ampicillin 2 g, 10.5 mg/l. The absorption rate was highest with bacampicillin, for which 90% of the absorption had occurred 1 hour after administration as compared to 2.5 hours after administration of ampicillin. The relative bioavailability was about 2--3 times higher after bacampicillin as compared to ampicillin. The data imply dose-dependent absorption of oral ampicillin in high doses as there seems to be a less than proportional increase in AUC. The urinary recovery after bacampicillin was 68--75% as compared to 25--41% after ampicillin. Higher doses gave a lower percentage recovery and this phenomenon was more pronounced with ampicillin.

Pharmacokinetic comparison of oral bacampicillin and parenteral ampicillin

Bacampicillin is a new oral prodrug which is rapidly converted to ampicillin during absorption from the gastrointestinal tract. High serum peaks of ampicillin are obtained. Bacampicillin orally was compared pharmacokinetically with parenteral ampicillin (intravenously and intramuscularly). A cross-over study on healthy volunteers showed that ampicillin concentrations after equimolar doses of bacampicillin orally and ampicillin intramuscularly were of the same order. The mean of the individual peak values (regardless of time of occurrence) after a dose of 800 mg of bacampicillin was 13.1 +/- 3.8 mug/ml. Absorption rates of the two doses were similar, as were their distribution volumes (approximately 25% of the body weight). Bioavailability was 87% for bacampicillin, compared to 71% for ampicillin.

Oral treatment of subacute bacterial endocarditis in children

Fourteen episodes of subacute bacterial endocarditis in 11 children were successfully treated with antibiotics, which in 13 cases were given largely by mouth. It is suggested that oral treatment of bacterial endocarditis should be considered for children who are only moderately but not severely ill, and who have sensitive organisms.

On the absorption and metabolism of 35S-ampicillin

An aqueous solution of 35S-ampicillin and polyethylene glycol (PEG 4000, unabsorbable marker) was administered orally to 6 healthy subjects with gastrointestinal tubes. The minimal absorption of radioactive material, as shown by urinary excretion of label, differed markedly between subjects and averaged 44% (25-67). As the mean cumulative uptake in the proximal jejunum was 31% (24-45), it appeared that some of the radioactivity had been taken up in more distal parts of the gastrointestinal tract. Chromatographic fractionation of gastrointestinal aspirates indicated that more than 95% of the label usually remained attached to the parent compound. The corresponding figure for radioactive material recovered from urine was about 80-85%. A similar degree of decomposition was also found for label excreted in the urine of an additional subject who received 35S-ampicillin intravenously. In this experiment the urine contained 87% of the administered radioactivity.

Sequence effect on ampicillin blood levels noted in an amoxicillin, ampicillin, and epicillin triple crossover study

Amoxicillin, ampicillin, and epicillin (500 mg of each) were given orally to fasting men and women in a triple crossover study. Peak serum concentrations were significantly higher for amoxicillin than for ampicillin and significantly lowest for epicillin. The concentrations of antibiotics in serum were comparable in men and women. Total urine recovery was highest for amoxicillin (56.7%) and lowest for epicillin (27.5%), and higher in men than in women for each of the three antibiotics. Saliva, sweat, and tears contained only very small amounts of amoxicillin and, rarely, ampicillin or epicillin. A significant (P < 0.02) sequence effect was noted in that peak serum concentrations of ampicillin were higher (6.4 mug/ml) if epicillin had been taken the previous week than when ampicillin was taken first (2.7 mug/ml).

Dissolution and bioavailability of the anhydrate and trihydrate forms of ampicillin

The solubilities and intrinsic dissolution rates of ampicillin anhydrate and trihydrate in distilled water and dilute hydrochloric acid at 37 degrees have been measured. The dissolution rates of these materials from loose filled hard gelatin capsules were determined and the in vivo bioavailabilities of the compounds compared. Small differences in the in vitro behaviour of the anhydrate and trihydrate forms were recorded but the in vivo availability of the two compounds was the same.

5-hydroxy-7-chlortetracycline. I. Preparation, isolation, and physicochemical properties

Studies on pivampicillin hydrochloride and ampicillin trihydrate, administered in capsules to healthy volunteers, indicated that pivampicillin was absorbed more efficiently from the gastrointestinal tract than ampicillin. Average peak concentrations of ampicillin in the serum after doses equimolar to 250 mg of ampicillin were 6.8 μg/ml at 56 min with pivampicillin and 1.96 μg/ml at 1 h 24 min with ampicillin. The maximal concentration after pivampicillin treatment was also higher than that recorded when twice the equimolar dose of ampicillin, which averaged 3.2 μg/ml at 1 h 42 min, was used. The urinary excretion of ampicillin, expressed as a percentage of the administered dose, averaged 67 to 73 and 25 to 29% after administration of pivampicillin and ampicillin, respectively. The bioavailability of ampicillin, taken as the area under the serum curve, obtained with pivampicillin at a 250-mg ampicillin dose level was superior to that obtained with a 500-mg dose of ampicillin. Comparison of a suspension intended for children, containing the pivampicillin free base with a suspension of ampicillin trihydrate, emphasized the difference recorded for the capsule preparations. Administration of pivampicillin with a meal rich in fat and protein had no depressant effect on the absorption. Concurrent administration of probenecid caused higher and prolonged concentrations of ampicillin in the serum.

Concentrations of ampicillin and chloramphenicol in the serum of patients with acute Salmonella enteric fever

Concentrations of ampicillin and chloramphenicol were measured in the serum of patients being treated for acute infections by Salmonella typhi or S. paratyphi A. Ampicillin was administered by the oral or intramuscular routes, whereas chloramphenicol was given orally only. Ampicillin concentrations were highest 1 hr after initiation of intramuscular therapy and 2 hr after oral administration. The serum concentration of ampicillin was significantly higher when it was given intramuscularly than when it was given orally. However, serum concentrations in orally treated patients were approximately the same at 1 hr after the fifth dose as they were 1 hr after the first dose, in contrast to intramuscularly treated patients, in whom the serum concentration of ampicillin was significantly lower 1 hr after the fifth dose. On the other hand, serum concentrations of chloramphenicol were significantly higher after the fifth dose than after the first dose. The rates of cure, relapse, and drug treatment failure were similar for all treatment regimens, and the drug concentrations attained in serum were generally above the minimal inhibitory concentration for the infecting salmonellae.

Amoxycillin: a new semi-synthetic penicillin

Amoxycillin (alpha-amino-p-hydroxybenzylpenicillin) is a new semi-synthetic penicillin with a broad spectrum of antibacterial activity similar to that of ampicillin. Penicillin-sensitive strains of staphylococci, streptococci, and pneumococci were sensitive to concentrations of 0.1 mug or less of amoxycillin/ml. Strains of Haemophilus influenzae were inhibited by a level of 0.5 mug/ml, and most strains of Escherichia coli, Proteus mirabilis, Shigella sonnei, Salmonella species, and Streptococcus faecalis were sensitive to a concentration of 5 mug or less of amoxycillin/ml. Penicillinase-producing strains of Staphylococcus aureus and strains of Pseudomonas aeruginosa, indole-positive Proteus, Klebsiella, and Enterobacter were insensitive to amoxycillin. The new penicillin was bactericidal in activity, as with other penicillins, and its antibacterial activity was not reduced in the presence of serum. After oral administration to volunteer subjects amoxycillin produced serum concentrations twice as high as those obtained with similar doses of ampicillin, and the penicillin was recovered unchanged in high concentrations in the urine. The absorption of amoxycillin was not greatly influenced by food, and administration of probenecid resulted in increased and more prolonged concentrations of amoxycillin in serum.

Comparative clinical pharmacology of amoxicillin and ampicillin administered orally

Ampicillin and amoxicillin (alpha-amino-p-hydroxybenzyl penicillin) were administered orally in 500-mg doses to eight fasting volunteers in a comparative study in which pharmacokinetic techniques were used. The absorption of amoxicillin was significantly better, as demonstrated by a higher mean peak serum concentration of 7.6 mug/ml as compared to 3.2 mug/ml for ampicillin, an average "area under the curve" that was approximately double that of ampicillin, and an 8-hr urinary recovery for amoxicillin of 60% as compared to 34% for ampicillin. Serum half-lives were the same for the two antibiotics, with values of 60.3 (+/-3.3) min for ampicillin and 61.3 (+/-5.6) min for amoxicillin. The latter drug gave measurable concentrations in the blood at 8 hr in all of eight volunteers, as compared to only three of eight with ampicillin.

Ampicillin levels in sputum, serum, and saliva

The ampicillin levels in sputum, serum, and saliva from 40 patients receiving a dose of 250 mg., 26 patients receiving a dose of 500 mg., and 11 patients receiving a dose of 1 g. were estimated. The ampicillin was given orally four times daily.

The 1-2 hour and 2-3 hour sputum levels were similar in individual patients. There was no difference in the range or mean sputum or saliva levels between specimens from patients receiving 250 mg. and 500 mg., but the levels were significantly higher after the 1 g. dose. The mean serum level showed a small increase after 500 mg. ampicillin as compared with the 250 mg. dose and a big increase after the 1 g. dose: only the latter difference was significant. The sputum levels were approximately 30 to 40 times lower than the corresponding serum levels. There was considerable scatter in the sputum level for any level of ampicillin in the serum: in only two of the 1-2 hour sputum specimens was there no detectable ampicillin.

There was no correlation between the sputum levels and either the body weight or the dose in milligrams per kilogram. There was no evidence that corticosteroids or diuretics affected the sputum level.

It was not possible to demonstrate any relationship between the purulence of the sputum and the level of ampicillin after doses of 250 mg. or 500 mg., but higher levels were found in the more purulent specimens after 1 g. doses.

Comparative study of the effect of three antibiotics on renal function

1. Therapeutic doses of colistin sulphomethate sodium B.P. (Colomycin), pento-N sulphomethylpolymyxin B sodium (Thiosporin) and ampicillin B.P. (Penbritin) as well as normal saline have been given to volunteers with normal kidney function.2. A blind crossover technique was used and the effects of the compounds on blood levels and clearances of urea and creatinine studied.3. All four treatments resulted in some changes in the parameters measured but were reversible. The most marked changes were found with pento-N sulphomethylpolymyxin B sodium and were also associated with severe side-effects.4. In contrast to penicillins it is established that the process of tubular secretion sensitive to probenecid block plays no part in the renal excretion of polymyxins.