| Amoxicillin CAS | 26787-78-0 |
|---|---|
| Ampicillin CAS | 69-53-4 |
| Antibiotic Family | Aminopenicillin |
| Amoxicillin Bioavailability | 74–92% (oral) |
| Ampicillin Bioavailability | 30–55% (oral) |
| Amoxicillin Half-Life | 61.3 min |
| Ampicillin Half-Life | 60–90 min (IV) |
| Common Grades | Trihydrate, Compacted, Sodium salt |
Amoxicillin and ampicillin are the two most widely prescribed aminopenicillin antibiotics in both human medicine and veterinary practice. While chemically related and sharing the same betalactam mechanism of action, they differ substantially in oral bioavailability, pharmacokinetic profile, and clinical applications. For pharmaceutical buyers and formulators sourcing aminopenicillin APIs, understanding these differences informs procurement decisions and formulation strategy.
Amoxicillin and ampicillin belong to the aminopenicillin subclass of betalactam antibiotics. Both are semi-synthetic derivatives of the penicillin G nucleus (6-aminopenicillanic acid, or 6-APA). The aminopenicillin designation refers to the amino group attached to the benzyl side chain, which distinguishes these compounds from earlier penicillins such as penicillin G and penicillin V. This structural feature extends the antibacterial spectrum to include certain Gram-negative organisms while retaining Gram-positive coverage.
The critical structural difference between amoxicillin and ampicillin is a single hydroxyl group in the para position of the benzyl ring. Amoxicillin carries this para-hydroxyl substitution; ampicillin does not. This seemingly minor modification accounts for the clinically significant differences in oral absorption between the two drugs. The para-hydroxyl group improves the molecule's stability at gastric pH and enhances its transport across the intestinal epithelium via peptide transporters. Both compounds are manufactured as trihydrate forms for oral solid dosage formulations and as sodium salts for parenteral administration. The molecular formula of amoxicillin trihydrate is C16H19N3O5S · 3H2O, while ampicillin trihydrate is C16H19N3O4S · 3H2O.
Both APIs are manufactured via enzymatic acylation of 6-APA with the appropriate side chain precursor, followed by crystallization as the trihydrate. The 6-APA starting material is itself produced through fermentation of Penicillium chrysogenum and subsequent enzymatic cleavage of penicillin G. China has become a major global hub for 6-APA production, which supports the country's strong position in downstream aminopenicillin API manufacturing. For a detailed look at amoxicillin API specifications, see Amoxicillin Trihydrate product page; for ampicillin specifications, see Ampicillin Trihydrate product page.
As aminopenicillins, amoxicillin and ampicillin share a nearly identical antibacterial spectrum. Both drugs bind to penicillin-binding proteins (PBPs) in the bacterial cell wall, inhibiting transpeptidation during peptidoglycan synthesis and ultimately causing cell lysis. Their spectrum extends beyond that of penicillin G to cover certain Gram-negative pathogens, including Haemophilus influenzae, Escherichia coli, Proteus mirabilis, Salmonella species, and Shigella species. Gram-positive coverage includes Streptococcus species (including Streptococcus pneumoniae), Enterococcus faecalis, and Listeria monocytogenes.
The aminopenicillins do not cover betalactamase-producing bacteria. Both amoxicillin and ampicillin are susceptible to hydrolysis by both penicillinases and extended-spectrum betalactamases (ESBLs). To address this limitation, betalactamase inhibitors such as clavulanic acid (for amoxicillin) or sulbactam (for ampicillin) are commonly co-formulated. These inhibitor combinations restore activity against many betalactamase-producing strains of H. influenzae, Moraxella catarrhalis, Staphylococcus aureus, and Bacteroides species. The inhibitor pairing is not interchangeable: clavulanic acid is pharmacokinetically matched with amoxicillin for co-administration, and sulbactam is paired with ampicillin. Both combination products are available in oral and parenteral formulations from manufacturers in China.
Neither aminopenicillin has clinically useful activity against Pseudomonas aeruginosa, Klebsiella species (most strains), Serratia species, or Acinetobacter species. Methicillin-resistant Staphylococcus aureus (MRSA) is uniformly resistant to aminopenicillins regardless of betalactamase inhibitor co-administration. For clinical and quality considerations in veterinary formulations, see Veterinary Amoxicillin Trihydrate and Veterinary Ampicillin Trihydrate.
Amoxicillin is a first-line therapy for community-acquired pneumonia, acute bacterial sinusitis, acute otitis media, and streptococcal pharyngitis. Amoxicillin plus clavulanic acid extends coverage to include betalactamase-producing pathogens commonly encountered in these indications. Ampicillin is also effective for respiratory infections but has been largely supplanted by amoxicillin for oral therapy due to the latter's superior oral bioavailability and less frequent gastrointestinal adverse effects. Ampicillin retains a role in severe respiratory infections requiring parenteral therapy, administered as intravenous ampicillin sodium.
Both amoxicillin and ampicillin achieve high urinary concentrations after oral or parenteral administration, making them suitable for treating uncomplicated urinary tract infections caused by susceptible Enterobacteriaceae. However, increasing resistance rates among E. coli urinary isolates have diminished the empiric use of aminopenicillins for UTI in many regions. Amoxicillin plus clavulanate is preferred over amoxicillin alone for urinary tract infections where betalactamase-producing organisms are prevalent. For parenteral therapy of complicated urinary tract infections, ampicillin combined with an aminoglycoside such as gentamicin provides synergistic bactericidal activity against enterococci.
Amoxicillin is a cornerstone of Helicobacter pylori eradication regimens worldwide. Standard triple therapy combines amoxicillin, clarithromycin, and a proton pump inhibitor (PPI) for 10 to 14 days. Bismuth quadruple therapy substitutes metronidazole and tetracycline for clarithromycin while retaining amoxicillin. Amoxicillin is preferred over ampicillin in these regimens because its superior gastric acid stability, higher oral bioavailability, and longer intragastric residence time produce more sustained drug concentrations at the site of infection. H. pylori rarely develops resistance to amoxicillin, making it the most reliable component of eradication regimens. Ampicillin is not a recommended substitute for amoxicillin in H. pylori therapy.
Amoxicillin trihydrate is extensively used in poultry production for the treatment of colibacillosis caused by Escherichia coli, as well as for enteritis and respiratory infections. It is administered through drinking water as a soluble powder, typically at doses of 10 to 20 mg/kg body weight for 3 to 5 days. Ampicillin trihydrate is also used in poultry but less frequently than amoxicillin due to the pharmacokinetic advantage of amoxicillin's higher oral bioavailability in birds. For poultry applications, water-soluble amoxicillin trihydrate powder grades from china amoxicillin trihydrate api manufacturer sources are typically formulated with excipients that ensure rapid dissolution and stability in drinking water systems.
In swine production, amoxicillin trihydrate is used for the treatment of respiratory infections caused by Actinobacillus pleuropneumoniae, Pasteurella multocida, and Streptococcus suis, as well as for enteric colibacillosis. Administration routes include oral (via feed or drinking water) and injectable formulations. Ampicillin trihydrate is employed as an injectable suspension for individual animal treatment of systemic infections. The compacted grade of ampicillin api china bulk is preferred for manufacturing injectable suspensions due to its superior flow properties and suspension stability. Typical dosing for swine ranges from 10 to 30 mg/kg depending on the severity of infection and the specific pathogen. A veterinary amoxicillin china supplier is typically expected to provide GMP documentation and veterinary-specific CoA parameters including particle size distribution appropriate for feed or water administration.
Aminopenicillins are used in aquaculture for the treatment of bacterial infections in fish and shrimp, including infections caused by Aeromonas, Vibrio, and Streptococcus species. Amoxicillin trihydrate is the preferred aminopenicillin for aquaculture due to its superior bioavailability in aquatic species when administered via medicated feed. The API must meet stringent purity requirements and be formulated into feed-grade premixes that ensure uniform distribution in pelleted feed. Chinese manufacturers supply significant volumes of amoxicillin API to aquaculture markets across Southeast Asia, where intensive shrimp and tilapia farming drives consistent demand. Relevant regulatory standards including ICH Q7 apply to the GMP production of aquaculture-grade aminopenicillin APIs.
Amoxicillin's defining pharmacokinetic advantage over ampicillin is its markedly higher oral bioavailability: 74 to 92 percent in fasting subjects compared with 30 to 55 percent for ampicillin. The para-hydroxyl group on amoxicillin's benzyl ring confers greater acid stability in the stomach and enhances transport through the intestinal peptide transporter PepT1. Food has minimal impact on amoxicillin absorption, and peak serum concentrations are typically achieved within 1 to 2 hours after oral administration. Amoxicillin distributes widely into body tissues and fluids, including middle ear fluid, sinus mucosa, bronchial secretions, and urine, where concentrations far exceed serum levels. The elimination half-life is approximately 61.3 minutes in adults with normal renal function. These favorable pharmacokinetic properties, combined with its broad antibacterial spectrum, explain why amoxicillin is the most frequently prescribed oral aminopenicillin worldwide.
Ampicillin's lower oral bioavailability limits its utility as an oral agent compared with amoxicillin, but ampicillin maintains an important role as an injectable antibiotic for moderate to severe infections. Following intravenous (IV) or intramuscular (IM) administration, ampicillin achieves high peak serum concentrations that decline with a half-life of 60 to 90 minutes in patients with normal renal function. Ampicillin distributes into cerebrospinal fluid when the meninges are inflamed and into synovial fluid, pleural fluid, and bile. Probenecid co-administration prolongs the half-life by inhibiting renal tubular secretion. Sodium ampicillin for injection is the standard parenteral form and is manufactured as a lyophilized powder for reconstitution. A china ampicillin trihydrate api supplier typically provides both trihydrate (for oral and suspension formulations) and sodium salt (for injectable formulations) grades from GMP-certified facilities.
Resistance to aminopenicillins is mediated primarily through betalactamase production (enzymatic hydrolysis of the betalactam ring), altered penicillin-binding proteins (PBPs) that reduce drug affinity, and decreased outer membrane permeability in Gram-negative organisms. The most clinically significant mechanism is betalactamase production, which is commonly plasmid-mediated and can spread rapidly among bacterial populations. TEM-1, TEM-2, and SHV-1 betalactamases hydrolyze both amoxicillin and ampicillin with comparable efficiency. Both drugs are equally susceptible to these enzymes, and there is complete cross-resistance between the two aminopenicillins in betalactamase-producing organisms.
Extended-spectrum betalactamases (ESBLs) of the CTX-M, TEM, and SHV families confer high-level resistance to all aminopenicillins, including inhibitor combinations in some cases. Carbapenemases (KPC, NDM, OXA-48) inactivate amoxicillin, ampicillin, and virtually all betalactam antibiotics, leaving few treatment options. Resistance rates vary geographically and by healthcare setting. In China and other regions with high antibiotic consumption, E. coli resistance to ampicillin exceeds 80 percent in some surveillance studies, as documented in CLSI antimicrobial susceptibility testing reports and peer-reviewed clinical data. Betalactamase inhibitor combinations (amoxicillin-clavulanate, ampicillin-sulbactam) partly address this resistance by restoring activity against organisms producing class A betalactamases, though they remain ineffective against ESBL and carbapenemase producers. Resistance monitoring is an essential component of aminopenicillin procurement strategy, particularly for veterinary applications where resistance patterns in food-producing animals influence both clinical outcomes and regulatory compliance.
Amoxicillin trihydrate API is manufactured to harmonized pharmacopoeia standards including the British Pharmacopoeia (BP), European Pharmacopoeia (EP), and United States Pharmacopeia (USP). Key specifications include an assay range of 95.0 to 102.0 percent (anhydrous basis), water content of 11.5 to 14.5 percent (consistent with the trihydrate form), pH of 3.5 to 5.5 (0.2 percent aqueous suspension), and specific optical rotation of +290 to +315 degrees. Related substances are tightly controlled with limits on individual impurities typically below 0.5 to 1.0 percent and total impurities below 2.0 to 3.0 percent depending on the specific monograph. Residual solvents must comply with ICH Q3C guidelines, with acetone and methylene chloride being the most commonly monitored residual solvents in amoxicillin manufacturing. Additional tests include heavy metals, bacterial endotoxins (for parenteral-grade material), and particle size distribution for compacted grades.
Ampicillin trihydrate API conforms to EP and USP monographs with comparable analytical requirements. The EP assay specification is 96.0 to 100.5 percent (anhydrous basis), with a water content of 12.0 to 15.0 percent. USP specifications are similar with slight variations in acceptance criteria. Related substances testing is critical, with particular attention to the dimer impurity (a polymerization product) and the penicilloic acid degradation product. The dimer content must typically remain below 0.5 percent, and any increase during stability testing indicates compromised storage conditions or manufacturing process weaknesses. Sodium ampicillin (for injection) has distinct monograph requirements with tighter controls on bacterial endotoxins, sterility, and particulate matter. For procurement of ampicillin api china bulk quantities, buyers should verify that the manufacturer holds a valid Certificate of Suitability (CEP) to the relevant EP monograph or an active US FDA Type II DMF.
Aminopenicillin APIs are available in standard powder form and as compacted (granulated) grades. Standard powder is suitable for most oral solid dosage formulations including tablets, capsules, and dry syrup powders. Compacted grades are produced through roller compaction followed by milling and sieving to achieve a target particle size distribution with improved flowability and bulk density. Compacted amoxicillin trihydrate and compacted ampicillin trihydrate are preferred for high-speed capsule filling and tablet compression operations where powder flow consistency directly affects weight uniformity and content uniformity. Compacted grades typically exhibit a bulk density of 0.45 to 0.65 g/mL and a tapped density of 0.60 to 0.85 g/mL, compared with 0.25 to 0.40 g/mL and 0.35 to 0.55 g/mL, respectively, for non-compacted powder. Particle size specifications are generally expressed as D10, D50, and D90 values determined by laser diffraction. Buyers should specify the required grade (powder or compacted) and particle size distribution when requesting quotations from china amoxicillin trihydrate api manufacturer or ampicillin suppliers.
China is the world's largest producer of amoxicillin trihydrate API, supported by an integrated supply chain from 6-APA fermentation through to finished API. Major production bases are concentrated in Hebei, Inner Mongolia, and Shandong provinces where key intermediates and fermentation capacity are co-located. Annual Chinese amoxicillin API production capacity exceeds 25,000 metric tons, of which a substantial portion is exported to markets in Europe, Southeast Asia, the Middle East, Africa, and Latin America. Leading manufacturers operate dedicated betalactam production facilities compliant with ICH Q7 and hold multiple regulatory filings including CEPs and US DMFs. Facility segregation is mandatory for betalactam APIs under EU GMP Annex 3 and PIC/S guidelines to prevent cross-contamination with non-betalactam products. When evaluating a china amoxicillin trihydrate api manufacturer, key verification points include GMP certificate validity, CEP or DMF status, on-site audit history, and the facility's dedicated beta-lactam production infrastructure.
China's ampicillin trihydrate API production is smaller in volume than amoxicillin production but serves a stable global market for both human and veterinary applications. Annual Chinese ampicillin API production capacity is estimated at 3,000 to 5,000 metric tons. The manufacturing process shares the same intermediate (6-APA) but uses a different side chain precursor for the acylation step. Several Chinese manufacturers produce both amoxicillin and ampicillin, leveraging shared fermentation and synthesis infrastructure while maintaining dedicated crystallization and finishing areas. A china ampicillin trihydrate api supplier with both products in portfolio offers procurement efficiencies for buyers who require both aminopenicillins. As with amoxicillin, facility segregation for betalactam APIs is a non-negotiable regulatory requirement. Verification should include confirmation that the manufacturing site has been inspected by a PIC/S-member regulatory authority or audited by a qualified third party within the last three years.
Quality verification for aminopenicillin APIs sourced from China follows a structured approach. Start by requesting the current GMP certificate and verifying that the issuing authority, facility name, and product scope match the production site. Confirm CEP validity through the EDQM Certification database and check FDA DMF status through the FDA Drug Master File database. Cross-reference the manufacturer against the FDA warning letter database and EU GMP non-compliance reports. Request batch-specific Certificates of Analysis (CoAs) covering assay, related substances, residual solvents, water content, pH, specific rotation, and (for injectable grades) bacterial endotoxins and sterility. For compacted grades, request particle size distribution data and bulk/tapped density values. Conduct independent third-party testing of evaluation samples against the relevant pharmacopoeia monograph. For ongoing supply, establish a quality agreement defining specifications, analytical methods, change control notification timelines, and audit rights. The API Quality Documentation Guide provides a detailed framework for document review during supplier qualification.
For pharmaceutical formulators and veterinary product manufacturers who use both amoxicillin and ampicillin APIs, combining procurement of both aminopenicillins through a single supplier or coordinated sourcing strategy offers tangible operational advantages. A supplier that manufactures or sources both APIs can provide consolidated documentation (GMP certificates, quality agreements, audit reports), which reduces the administrative burden on the buyer's quality assurance and regulatory affairs teams. Combined orders simplify logistics: a single shipment consolidating both amoxicillin and ampicillin reduces freight costs per kilogram compared with separate smaller shipments from different suppliers. Combined orders may also qualify for volume-based pricing improvements, particularly when the total order value or total weight triggers a higher discount tier.
Risk diversification remains important. Buyers should maintain qualification of at least one alternative supplier for each API even when consolidating most volume with a primary supplier. The betalactam raw material market in China is subject to price fluctuations driven by 6-APA intermediate pricing, environmental regulation enforcement, and energy cost changes. A combined procurement strategy that balances consolidation benefits with supply security is the most prudent approach for buyers in both human pharmaceutical and veterinary markets.