Amoxicillin

Absorption

Amoxicillin is approximately 60% bioavailable. A 250mg dose of oral amoxicillin reaches a Cmax 3.93±1.13mg/L with a Tmax 1.31±0.33h and an AUC of 27.29±4.72mg*h/L. A 875mg dose of oral amoxicillin reaches a Cmax 11.21±3.42mg/L with a Tmax 1.52±0.40h and an AUC of 55.04±12.68mg*h/L.

Toxicity

Patients experiencing an overdose may present with hematuria, oliguria, abdominal pain, acute renal failure, vomiting, diarrhea, rash, hyperactivity, and drowsiness. Treat overdose with symptomatic and supportive treatment, which may include emesis or hemodialysis.

Chemical properties

solid

Originator

Arnoxil,Bencard,UK,1972

The Uses of Amoxicillin

Amoxicillin is an antibiotic used in the treatment of various bacterial infections.

The Uses of Amoxicillin

Antibacterial;Bacterial transpeptidase inhibitor

Indications

Amoxicillin alone is indicated to treat susceptible bacterial infections of the ear, nose, throat, genitourinary tract, skin, skin structure, and lower respiratory tract. Amoxicillin is given with calvulanic acid to treat acute bacterial sinusitis, community acquired pneumonia, lower respiratory tract infections, acute bacterial otitis media, skin and skin structure infections, and urinary tract infections. Amoxicillin is given with omeprazole in the treatment of Helicobacter pylori (H. pylori) infection.
Amoxicillin is used in combination with vonoprazan and clarithromycin as co-packaged triple therapy or in combination with vonoprazan as co-packaged dual therapy to treat H. pylori infection in adults.

What are the applications of Application

Amoxicillin is a peptidoglycan polymerization inhibitor

Background

Amoxicillin, or BRL-2333, is a penicillin G derivative first described in the literature in 1972. Amoxicillin has similar activity to penicillin and ampicillin, but leads to higher serum concentrations than ampicillin.
Amoxicillin was granted FDA approval on 18 January 1974.

Definition

ChEBI: A penicillin in which the substituent at position 6 of the penam ring is a 2-amino-2-(4-hydroxyphenyl)acetamido group.

Indications

Amoxycillin, like ampicillin, has a broad spectrum of use. Indications for use are the same as with ampicillin. Synonyms of this drug are amoxican, amoxil, larotid, robamox, trimox, vimox, utimox, and others. Undoubtedly, analogs of ampicillin that are substituted at the amine fragment of phenylglycine (azolcillin, mezlocillin, piperacillin) should be included in this same group of compounds.

Manufacturing Process

Ethyl chlorocarbonate (2.2 ml) was added to an ice cold solution of O,N-dibenzyloxycarbonyl-p-oxy-dl-α-aminophenylacetic acid (10 grams) and triethylamine (3.85 ml) in dry acetone (193 ml). The mixture was stirred at 0°C for 5 minutes during which triethylamine hydrochloride precipitated. The suspension was cooled to -30°C and stirred vigorously while adding as rapidly as possible an ice cold solution of 6-aminopenicillanic acid (5.85 grams) in 3% aqueous sodium bicarbonate (193 ml), the temperature of the mixture never being allowed to rise above 0°C. The resulting clear solution was stirred for 30 minutes at 0°C, and then for a further 30 minutes, without external cooling, and finally extracted with diethyl ether (3 x 200 ml) only the aqueous phase being retained.
This aqueous solution was brought to pH 2 by the addition of hydrochloric acid and the 6-(O,N-dibenzyloxycarbonyl-p-oxy-dl-α- aminophenylacetamido)penicillanic acid so liberated was extracted into diethyl ether (50 ml and 2 portions of 30 ml). The ether phase was washed with water (3 x 5 ml) and the water washings were discarded.
Finally, the penicillin was converted to the sodium salt by shaking the ether solution with sufficient 3% sodium bicarbonate to give a neutral aqueous phase, separating the latter and evaporating it at low pressure and temperature below 20°C. The product was finally dried over phosphorus pentoxide in vacuo to give sodium 6-(O,N-dibenzyloxycarbonyl-p-oxy-dl-α- aminophenylacetamido)-penicillanate (9.2 grams).
A suspension of palladium on calcium carbonate (36 grams of 5%) in water (150 ml) was shaken in an atmosphere of hydrogen at room temperature and atmospheric pressure for 1 hour. A neutral solution of sodium 6-(O,Ndibenzyloxycarbonyl- p-oxy-dl-α-aminophenylacetamido)penicillanate (9 grams) in water (100 ml) was then added and shaking in hydrogen was resumed for one hour. The suspension was then filtered and the collected catalyst was washed well with water without being allowed to suck dry between washings. The combined filtrate and washings were then brought to pH 6.5 with dilute hydrochloric acid and evaporated to dryness at reduced pressure and temperatures below 20°C. The product was finally dried over phosphorus pentoxide in vacuo to give a solid (5.4 grams) containing 6-(phydroxy- dl-α-aminophenylacetamido)penicillanic acid.

brand name

Amoxil (GlaxoSmithKline); Dispermox (Ranbaxy); Larotid (GlaxoSmithKline); Trimox (Apothecon) [Name previously used: Amoxycillin.].

Therapeutic Function

Antibacterial

Antimicrobial activity

The antibacterial spectrum is identical to that of ampicillin and there are few differences in antibacterial activity . Like ampicillin, amoxicillin is unstable to most β-lactamases. It has useful activity against Helicobacter pylori (<1% resistance), and is included in most combination regimens for the treatment of H. pylori infections.

Acquired resistance

There is complete cross-resistance with ampicillin. Its action against many β-lactamase-producing strains can be restored by co-administration with β-lactamase inhibitors.

Flammability and Explosibility

Non flammable

Contact allergens

Amoxicillin is both a topical and a systemic sensitizer. Topical sensitization occurs in health care workers. Systemic drug reactions are frequent, such as urticaria, maculo-papular rashes, baboon syndrome, acute generalized exanthematous pustulosis, or even toxic epidermal necrosis. Cross-reactivity is common with ampicillin, and can occur with other penicillins.

Biochem/physiol Actions

Amoxicillin fights infections in the body within an hour after taking it. The penicillin-based medication gets its strength from consistent use of multiple doses per day. Amoxicillin often relieves symptoms in less than 72 hours and stays in your system for 24 hours.

Mechanism of action

Amoxicillin shows a bactericidal (kills microorganisms) effect against susceptible organisms (bacteria that are unable to grow in the presence of the drug) during their stage of active multiplication. Amoxicillin mode of action is similar to ampicillin, and thus it works by preventing the synthesis of the mucopeptide (a protein responsible for the growth of bacteria) present in the cell wall, which in turn leads to the death of the bacteria.

Pharmacokinetics

Amoxicillin competitively inhibit penicillin binding proteins, leading to upregulation of autolytic enzymes and inhibition of cell wall synthesis. Amoxicillin has a long duration of action as it is usually given twice daily. Amoxicillin has a wide therapeutic range as mild overdoses are not associated with significant toxicity. Patients should be counselled regarding the risk of anaphylaxis, Clostridium difficile infections, and bacterial resistance.

Pharmacokinetics

Oral absorption: 75–90%
C_max 500 mg oral: 5.5–7.6 mg/L after 1–2 h
500 mg intramuscular: c. 14 mg/L after 1–2 h
Plasma half-life: 1 h
Volume of distribution: 0.3 L/kg
Plasma protein binding: 17–20%
Absorption and distribution
Oral absorption produces over twice the peak concentration achieved by comparable doses of ampicillin, allowing less frequent dosing intervals. Absorption is unaffected by food. It is well-distributed in multiple body fluids, including pleural, peritoneal and middle ear fluid. It does not penetrate well into the CSF.
Metabolism and excretion
Some 10–25% is converted to the penicilloic acid. Between 50% and 70% of unchanged drug is recovered in the urine in the first 6 h after a dose of 250 mg. Plasma levels are elevated and prolonged by the administration of probenecid.

Clinical Use

Isolates should be tested for susceptibility before use, especially for serious infections.
Ear, nose and throat infections other than pharyngitis, which may mask glandular fever
Tracheobronchitis, bronchitis, pneumonia
Genitourinary tract infections, including gonorrhea
Infections of skin and soft tissues due to streptococci and susceptible staphylococci
Helicobacter pylori infection (in combination with a proton pump inhibitor and at least one other antimicrobial agent such as clarithromycin)
Prophylaxis of endocarditis in patients undergoing dental treatment and other procedures

Clinical Use

Amoxicillin, 6-[D-(－)-α-amino-p- hydroxyphenylacetamido]penicillanic acid (Amoxil, Larotid, Polymox), a semisyntheticpenicillin introduced in 1974, is simply the p-hydroxyanalog of ampicillin, prepared by acylation of 6-APA with phydroxyphenylglycine.Its antibacterial spectrum is nearly identical with that ofampicillin, and like ampicillin, it is resistant to acid, susceptibleto alkaline and β-lactamase hydrolysis, andweakly protein bound. Early clinical reports indicated thatorally administered amoxicillin possesses significantadvantages over ampicillin, including more complete GIabsorption to give higher plasma and urine levels, lessdiarrhea, and little or no effect of food on absorption.50Thus, amoxicillin has largely replaced ampicillin for thetreatment of certain systemic and urinary tract infectionsfor which oral administration is desirable. Amoxicillin isreportedly less effective than ampicillin in the treatment ofbacillary dysentery, presumably because of its greater GIabsorption. Considerable evidence suggests that oral absorptionof α-aminobenzyl–substituted penicillins (e.g.,ampicillin and amoxicillin) and cephalosporins is, at leastin part, carrier mediated, thus explaining their generallysuperior oral activity.Amoxicillin is a fine, white to off-white, crystallinepowder that is sparingly soluble in water. It is available invarious oral dosage forms. Aqueous suspensions are stablefor 1 week at room temperature.

Side Effects

Amoxicillin is generally well tolerated, side effects being those common to penicillins, but including non-allergic rashes in patients with glandular fever. As the drug is well absorbed, diarrhea is generally infrequent and rarely sufficiently severe to require withdrawal of treatment. Common side effects of Amoxicillin include Diarrhoea (loose stools), Headache, Nausea (vomiting sensation), Vomiting, Rash, Anaphylaxis (allergic condition), and Anaemia (lack of blood). Serious side effects of Amoxicillin include Thrombocytopenia (deficiency of platelets), Convulsions (involuntary movements of body muscles), Cholestatic jaundice (jaundice caused due to the stoppage of bile from the liver), Meningitis (inflammation of brain and spinal membranes), and Vasculitis (inflammation of blood vessels).

Synthesis

Amoxycillin, [2S-[2α,5α,6β(S)]]-3,3-dimethyl-7-6-[[amino-(4-hydroxyphenyl)-acetyl]amino]-4-thia-1-azabicyclo[3.2.0]-heptan-2-carboxylic acid (32.1.1.21), is synthesized in two ways. The first uses an enamine protection of the amino group of 4-hydroxyphenylglycine, which begins with the sodium salt of 4-hydroxyphenylglycine, which is reacted with the acetoacetic ester to form an enamine—the sodium salt of a phydroxyphenyl acetic acid, α-[(3-ethoxy-1-methyl-3-oxo-1-propenyl)amino]-4-hydroxy- (32.1.1.19). Reacting the resulting aminocrotonate with the ethyl chloroformate in N-methylmorpholine gives the corresponding mixed anhydride (32.1.1.20), which is reacted with trimethylsilyl ester of 6-APA.

The second method uses a direct reaction of D-(-)-2-(4-hydroxyphenyl)glycine chloride hydrochloride with trimethylsylil ester of 6-APA.

The trimethylsilyl ester of 6-APA needed for the reaction is in turn synthesized by reacting trimethylchlorosilylane with 6-APA in the presence of trimethylamine.

Veterinary Drugs and Treatments

Amoxicillin/potassium clavulanate tablets and oral suspension products are approved for use in dogs and cats for the treatment of urinary tract, skin and soft tissue infections caused by susceptible organisms. It is also indicated for canine periodontal disease due to susceptible strains of bacteria.

Veterinary Drugs and Treatments

The aminopenicillins have been used for a wide range of infections in various species. FDA-approved indications/species, as well as non-approved uses, are listed in the Dosages section below.

Drug interactions

Potentially hazardous interactions with other drugs
Amoxicillin can reduce the excretion of methotrexate (increased risk of toxicity).

Metabolism

Incubation with human liver microsomes has lead to the detection of 7 metabolites. The M1 metabolite has undergone hydroxylation, M2 has undergone oxidative deamination, M3 to M5 have undergone oxidation of the aliphatic chain, M6 has undergone decarboxylation, and M7 has undergone glucuronidation.

Metabolism

Amoxicillin is metabolised to a limited extent to penicilloic acid which is excreted in the urine. About 60% of an oral dose of amoxicillin is excreted unchanged in the urine by glomerular filtration and tubular secretion. Probenecid reduces renal excretion. High concentrations have been reported in bile; some may be excreted in the faeces.