Cefaclor monohydrate. Chemical Name: 3-chloro-7-D- (2-phenylglycinamido) -3-cephem-4-carboxylic acid monohydrate Structural Formula: HO O
.
Cl
O N H2O N H S H H H2N H Molecular Formula: C15H14CIN3O4S.H2O Molecular Weight: 385.83 CAS Registry Number: 70356-03-5
Cefaclor (monohydrate) is a white to off-white crystalline powder, slightly soluble in water, but is insoluble in alcohol and chloroform.
Cefaclor CD is well absorbed after oral administration, with peak plasma levels being reached in about 2 hours. Following a single dose of cefaclor CD 375 mg Cmax is approximately 3.8 g/mL and AUC is 11.5
g.h/mL. When taken with food the time to reach maximum plasma levels is increased to about 3 hours
and Cmax increases by 20%. The effects of food on Cmax and Tmax are also seen with other modified release preparations of cefaclor. Other studies with sustained release preparations of cefaclor have shown that although it can be taken with or without food, total absorption is enhanced with food. When it was given within one hour after a meal, the bioavailability of sustained release cefaclor was greater than 90%, using cefaclor taken fasting as a reference. When taken in the fasting state, the bioavailability of sustained release cefaclor was 77% that of cefaclor. Compared to cefaclor (fasted state), mean peak plasma concentrations of sustained release cefaclor (both fed and fasted states) were delayed 40 to 90 minutes and were lower. Concomitant administration of cimetidine does not affect the rate or extent of absorption. Administration of magnesium or aluminium hydroxide containing antacids one hour after sustained-release preparations of cefaclor had no effect on the rate of absorption, but resulted in a 17% decrease in the extent of absorption. The effect of antacids taken at other times is uncertain. Following administration of 375 mg, 500 mg and 750 mg tablets to fed subjects, average peak serum concentrations of 4, 8, and 11 mg/mL, respectively, were obtained within 2.5 to 3 hours. No drug accumulation was noted when it was given twice daily for 21/2 days. The plasma half life in healthy subjects is approximately 50 minutes. In elderly subjects (>65 years) with normal serum creatinine values, a higher peak plasma concentration and area under the curve (AUC) are effects resulting from mildly diminished real function and are not expected to have clinical significance. Therefore, dosage changes are not necessary in elderly subjects with normal renal function. There is no evidence of metabolism of cefaclor in humans.
In vitro tests demonstrate that the bactericidal action of the cephalosporins results from inhibition of cell wall synthesis. Cefaclor is stable in the presence of bacterial -lactamases; consequently, -lactamase producing organisms resistant to penicillins and some cephalosporins may be susceptible to cefaclor. Cefaclor may have useful activity against the following organisms in vitro and in clinical infections:
Gram-Positive Organisms: Staphylococcus aureus Staphylococcus saprophyticus Streptococcus pneumoniae
Streptococcus pyogenes
(group A Streptococci);
Note: Cefaclor is not active against methicillin resistant Staphylococci. Gram-Negative Organisms:
Haemophilus influenzae
Moraxella (Branhamella) catarrhalis Escherichia coli
Klebsiella pneumoniae Proteus mirabilis
Note: Pseudomonas sp. Acinetobacter calcoaceticus, Enterococci, Enterobacter sp., indole-positive Proteus, and Serratia sp. are resistant to cefaclor. Methicillin resistant strains are also resistant to cefaclor.
Dilution or Diffusion Techniques - either quantitative (MIC) or breakpoint, should be used following a regularly updated, recognised and standardised method (e.g. NCCLS). Standardised susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. A report of "Susceptible" indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable. A report of "Intermediate" indicates that the result should be considered equivocal, and if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone, which prevents small, uncontrolled technical factors from causing major discrepancies in interpretation. A report of "Resistant" indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected.
Note
: The prevalence of resistance may vary geographically for selected species and local information on resistance is desirable, particularly when treating severe infections.
For the treatment of the following infections caused by susceptible organisms, in adults and children 12 years and older:
Community acquired pneumonia of mild to moderate severity (excluding atypical pneumonia),
Acute bronchitis and acute exacerbations of chronic bronchitis.
Upper respiratory infections, including pharyngitis, tonsillitis and acute bacterial sinusitis.
Symptomatic lower urinary tract infections, including cystitis.
Skin and skin structure infections.
Note. Penicillin is the usual drug of choice in the treatment and prevention of streptococcal infections, including the prophylaxis of rheumatic fever. Cefaclor CD is generally effective in the eradication of Streptococci from the oropharynx; however, substantial data establishing the efficacy of Cefaclor CD in the subsequent prevention of rheumatic fever are not available. Bacteriological studies to determine the causative organism and its susceptibility to cefaclor should be performed. Therapy may be started while awaiting the results of these studies. Once these results become available, antimicrobial therapy should be adjusted accordingly
Known allergy to cephalosporins or previous experience of a major allergy to penicillin (see PRECAUTIONS) or any of the excipients listed (see PRESENTATION AND STORAGE CONDITIONS).
The safety and efficacy of this product have not been established in children
Except under special circumstances, this medication should not be used when the following medical problem exists:
Cephalosporin antibiotics should be administered cautiously in this patient group. There is clinical and laboratory evidence of partial cross allergenicity of the penicillins and the cephalosporins and there are instances in which patients have had reactions, including anaphylaxis, to both drug classes. Serious and occasionally fatal hypersensitivity (anaphylactic/anaphylactoid) reactions have been reported in patients on penicillin/cephalosporin therapy. Although anaphylaxis is more frequent following parenteral therapy, it has occurred in patients on oral penicillins/cephalosporins. These reactions are more likely to occur in individuals with a history of penicillin hypersensitivity and/or a history of sensitivity to multiple allergens. There have been reports of individuals with a history of penicillin/cephalosporin hypersensitivity who have experienced severe reactions when treated with a penicillin/cephalosporin.
Past history of a severe allergic reaction to drug from the penicillin or cephalosporin group of drugs is a contraindication to the use of cefaclor. Before initiating therapy with any cephalosporin careful inquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins or other allergens. If an allergic reaction occurs, cefaclor should be discontinued and the appropriate therapy instituted. Serious anaphylactoid reactions require immediate emergency treatment with adrenaline. Oxygen, intravenous steroids and airway management, including intubation, should also be administered as indicated.
Broad-spectrum antibiotics should be prescribed with caution in individuals with a history of gastrointestinal disease, especially ulcerative colitis, regional enteritis, or antibiotic-associated colitis.
Risk-benefit should be considered when the following medical problems exist:
Antibiotic associated pseudomembranous colitis has been reported with many antibiotics including cefaclor. A toxin produced by Clostridium difficile appears to be the primary cause. The severity of the colitis may range from mild to life threatening. It is important to consider this diagnosis in patient who develop diarrhoea or colitis in association with antibiotic use (this may occur up to several weeks after cessation of antibiotic therapy), Mild cases usually respond to drug discontinuation alone. However, in moderate to severe cases appropriate therapy such as oral antibacterial agents effective against Cl. difficile should be considered. Fluids, electrolytes and protein replacement therapy should be provided when indicated. Drugs which delay peristalsis, e.g. opiates and diphenoxylate with atropine (Lomotil), may prolong and/or worsen the condition and should not be used.
History of bleeding disorders
All cephalosporins may cause hypoprothrombinaemia and, potentially, bleeding.
As with antibiotic therapy in general, administration of cefaclor should be continued for a minimum of 48 to 72 hours after the patient becomes asymptomatic or after evidence of bacterial eradication has been obtained. A minimum of 10 days of treatment is recommended in infections caused by group A
-haemolytic Streptococci in order to guard against the risk of rheumatic fever or glomerulonephritis.
This may result in the overgrowth of non-susceptible organisms. Careful observation of the patient is essential. If superinfection occurs during therapy, appropriate measures should be taken.
Broad spectrum antibiotics should be prescribed with caution in individuals with a history of gastrointestinal disease, especially ulcerative colitis, regional enteritis, or antibiotic-associated colitis.
Many cephalosporins are excreted renally. Cefaclor should be administered with caution in the presence of markedly impaired renal function. Since the half-life of cefaclor in anuria is 2.3 to 2.8 hours, dosage adjustments for patients with moderate or severe renal impairment are usually not required. Clinical experience with cefaclor under such conditions is limited; therefore, careful clinical observation and laboratory studies should be made.
Cefaclor should be used with caution in patients with hepatic disease, as documented clinical experience in this group of patients is lacking.
Adequate and well-controlled studies in humans have not been done. Reproduction studies have revealed no evidence of impaired fertility.
The oral administration of high dose cefaclor (500 mg/kg) in pregnant rats and mice has resulted in a slight increase of minor skeletal malformation. Safety of this product for use during pregnancy has not been established. Cefaclor should not be used in women of childbearing potential unless, in the judgement of the treating clinician, its use is considered essential to the welfare of the patient and the expected benefits outweigh potential risks.
Category B1: Drugs which have been taken by only a limited number of pregnant women and women
of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human foetus having been observed. Studies in animals have not shown evidence of an increased occurrence of foetal damage.
Cefaclor has not been studied for use during labour and delivery. Treatment should be given only if clearly needed.
No studies have been done with Cefaclor CD. Small amounts of cefaclor have been detected in breast milk following administration of single 500 mg doses of cefaclor. Average levels were 0.18, 0.20, 0.21 and 0.16 mg/mL at 2, 3, 4 and 5 hours respectively. Trace amounts were detected at 1 hour. The effect on breastfed infants is not known. Caution should be exercised when cefaclor is administered to a breastfeeding woman.
Safety and effectiveness of this product has not been studied in children. Serum sickness-like reactions including arthritis and arthralgia have been reported more frequently in children than in adults with the use of cefaclor.
Cephalosporins have been used in the geriatric population, and no geriatrics-specific problems have been documented to date. However, elderly patients are more likely to have an age-related decrease in renal function, which may require and adjustment in dosage and/or dosing interval in patients receiving cephalosporins.
Dental
Long-term therapy with cephalosporins may allow for the overgrowth of Candida albicans, resulting in oral candidiasis.
Studies in animals have not been performed to evaluate the carcinogenic potential for cefaclor.
Studies in animals have not been performed to evaluate the mutagenic potential for cefaclor.
Anticoagulants, coumarin- or indandione-derivatives, or Heparin or Thrombolytic agents
Because all cephalosporins can inhibit vitamin K synthesis by suppressing gut flora, prophylactic
vitamin K therapy is recommended when any of these medications is used for prolonged periods in malnourished or seriously ill patients.
Platelet aggregation inhibitors
Hypoprothrombinaemia induced by large doses of salicylates and/or cephalosporins, and the gastrointestinal ulcerative or hemorrhagic potential of nonsteroidal anti-inflammatory drugs (NSAIDs), salicylates, or sulfinpyrazone may increase the risk of haemorrhage.
Antacids: The extent of absorption of cefaclor is diminished if magnesium or aluminium hydroxide containing antacids are taken within one hour of administration.
Cimetidine
did not alter either the rate or extent of absorption of cefaclor.
Probenecid: Probenecid decreases renal tubular secretion of those cephalosporins excreted by this mechanism, resulting in increased and prolonged cephalosporin serum concentrations, prolonged elimination half-life, and increased risk of toxicity. No other significant drug interactions were noted during clinical trials.
Glucose, urine: Administration of cefaclor may result in a false positive reaction for glucose in the urine. This phenomenon has been seen in patients taking cephalosporin antibiotics when the test is performed using Benedict's and Fehling's solutions and also with Clinitest tablets but not with Tes-Tape. (Glucose Enzymatic Test Strip, USP)
Coombs' (antiglobulin) tests
: Positive direct Coombs' tests have been reported during treatment with cefaclor. In haematological studies or in transfusion cross matching procedures when antiglobulin tests are performed on the minor side or in Coombs' testing of newborn infants whose mothers have received cephalosporin antibiotics before parturition, it should be recognised that a positive Coombs' test may be due to the drug.
Prothrombin time (PT):
May be prolonged.
Creatinine, serum:
Concentrations may be increased.
Carnitine or Haematocrit:
Values may decrease during therapy.
Clinical Trials
The majority of adverse reactions observed in clinical trials of sustained-release preparations of cefaclor were mild and transient. Drug related adverse reactions requiring discontinuation of therapy occurred in 1.7% of patients. The following adverse reactions have been reported following use of sustained-release preparations of cefaclor in clinical trials. Incidence rates were less than 1% except where otherwise noted:
Gastrointestinal
Diarrhoea (3.4%), nausea (2.5%), vomiting and dyspepsia.
Hypersensitivity
Rash, urticaria or pruritus occurred in approximately 1.7% of patients. One serum sickness-like reaction (0.03%) was reported among the 3,272 patients treated with the sustained-release preparation of cefaclor during the controlled clinical trials.
Blood and lymphatic system disorders:
Eosinophilia.
Superinfection
Vaginal moniliasis (2.5%) and vaginitis (1.7%). Adverse events reported during a clinical trial of sustained release cefaclor (750 mg bid) vs. cefaclor capsules (500 mg tid) in patients with acute bacterial sinusitis are shown below. All adverse events occurring at an incidence of 2% or greater are included:
| Sustained-Release Cefaclor n=147 | Cefaclor Capsules n=150 | |
| Headache | 8 (5.4%) | 4 (2.7%) |
| Diarrhoea | 6 (4.1%) | 4 (2.7%) |
| Abdominal pain | 5 (3.4%) | 7 (4.7%) |
| Asthenia | 2 (2.0%) | 5 (3.3%) |
| Epistaxis | 3 (2.0%) | 0 (0.0%) |
| Pain | 3 (2.0%) | 1 (0.7%) |
| Vaginitis | 2 (1.4%) | 3 (2.0%) |
Causal Relationship Uncertain
The following adverse effects have been reported in patients treated with sustained-release preparations of cefaclor; the causal relationship is uncertain; incidence rates were less than 1% except where otherwise noted:
Central Nervous System
Headache (3.2%), dizziness and somnolence.
Hepatic
Transient elevations in AST, ALT and alkaline phosphatase.
Renal
Transient increases in serum urea or creatinine and abnormal urinalysis.
Blood and Lymphatic system disorders
Transient thrombocytopenia, leucopoenia, lymphocytosis, neutropenia..
Patients Treated with Cefaclor
In addition, the following adverse reactions and altered laboratory tests have been reported in patients treated with the regular (not sustained-release) cefaclor preparations:
Gastrointestinal
The most frequent side effect has been diarrhoea. Nausea and vomiting have been reported rarely. Colitis, including rare instances of pseudomembranous colitis, has been reported in conjunction with therapy with cefaclor (see PRECAUTIONS). Symptoms of pseudomembranous colitis may appear either during or after antibiotic treatment.
Immune system disorders
Allergic reactions, such as urticaria and morbilliform eruptions, have been observed. These reactions usually subsided upon discontinuation of the drug. Fever and angioedema have been reported rarely. Cases of serum sickness-like reactions have been reported with the use of cefaclor. These have been reported more frequently in children than in adults, with an overall occurrence ranging from 0.5% (1 in 200) in one trial, to 0.024% (2 in 8,346) in overall clinical trials (with an incidence in children in clinical trials of 0.055%). The worldwide reporting rate for serum-sickness-like reactions in adults is very rare (<0.01%). Serum sickness-like reactions are characterised by findings of erythema multiforme, rashes and other skin manifestations accompanied by arthritis/arthralgia, with or without fever, and differ from classic serum sickness in that there is infrequently associated lymphadenopathy and proteinuria, no circulating immune complexes and no evidence to date of sequelae of the reaction. While further investigation is ongoing, serum sickness-like reactions appear to be due to hypersensitivity and more often occur during or following a second (or subsequent) course of therapy with cefaclor. Such reactions have been reported more frequently in children than in adults. Signs and symptoms usually occur a few days after initiation of therapy and subside within a few days after cessation of therapy; occasionally these reactions have resulted in hospitalisation, usually of short duration (median hospitalisation: 2 to 3 days, based on post-marketing surveillance studies). In those requiring hospitalisation, the symptoms have ranged from mild to severe at the time of admission with more of the severe reactions occurring in children. Antihistamines and glucocorticoids appear to enhance resolution of the signs and symptoms. No serious sequelae have been reported. More severe hypersensitivity reactions, including Stevens-Johnson syndrome and toxic epidermal necrolysis have been reported rarely. Anaphylaxis may be more common in patients with a history of penicillin allergy. The worldwide reporting rate for anaphylaxis in the total population is very rare (<0.01%). Anaphylactoid events may present as solitary symptoms, including angioedema, asthenia, oedema (including face and limbs), dyspnoea, paraesthesias, syncope, or vasodilatation. Rarely, hypersensitivity symptoms may persist for several months. Positive direct Coombs' test and genital pruritus have been reported. The following reactions have been reported in patients treated with cefaclor:
Renal and urinary disorders. Hepatobiliary disorders.
Reversible interstitial nephritis Hepatic dysfunction, including transient hepatitis and cholestatic jaundice have been reported rarely.
Blood and lymphatic system disorders.
Eosinophilia, transient lymphocytosis leucopoenia, and rarely, thrombocytopenia, thrombocytosis, increased prothrombin time, with or without clinical bleeding, in patients receiving cefaclor and warfarin concomitantly; haemolytic anaemia, aplastic anaemia, agranulocytosis, reversible neutropenia of possible clinical significance,
Superinfection
Nervous system disorders.
Immune system disorders Other
There have also been reports of transient fluctuations in leucocyte count, predominantly lymphocytosis in infants and young children. Genital pruritus, moniliasis or vaginitis. Rarely, reversible hyperactivity, hypertonia, nervousness, insomnia, confusion, dizziness, headache, somnolence and hallucinations Angioedema and fever have been reported rarely. Transitory abnormalities in clinical laboratory test results have been reported, but their clinical significance is uncertain. These include slight elevations in AST, ALT or alkaline phosphatase values; and slight elevations in serum urea or serum creatinine or abnormalities of urinalysis (haematuria, pyuria). The following adverse reactions have been reported in patients treated with other beta-lactam antibiotics:
Renal dysfunction, and toxic nephropathy.
Several beta-lactam antibiotics have been implicated in triggering seizures, particularly in patients with renal impairment when the dosage was not reduced. If seizures associated with drug therapy should occur, the drug should be discontinued. Anticonvulsant therapy can be given if clinically indicated.
Administer orally. Cefaclor CD can be taken with or without food; however absorption is enhanced when Cefaclor CD is administered with food (see PHARMACOLOGY, Pharmacokinetics). The tablets should not be cut, crushed or chewed.
The usual adult dosage is 375 mg twice daily. For pneumonia, and acute bacterial sinusitis the recommended dosage is 750 mg twice daily. For acute bacterial sinusitis Cefaclor CD should be taken for 10 days. For infections involving S. pyogenes (group A Streptococci), a therapeutic dosage of Cefaclor CD should be administered for at least ten days.
For patients with markedly impaired renal function, see PRECAUTIONS.
The toxic symptoms following an overdose of cefaclor may include nausea, vomiting, epigastric distress and diarrhoea. The severity of the epigastric distress and the diarrhoea are dose related. If other symptoms are present, it is probable that they are secondary to an underlying disease state, an allergic reaction, or the effects of other intoxication.
In managing overdosage, consider the possibility of multiple drug overdoses, interaction among drugs, and unusual drug kinetics in the patient. Protect the patient's airway and support ventilation and perfusion. Meticulously monitor and maintain, within acceptable limits, the patient's vital signs, blood gases, serum electrolytes, etc. Absorption of drugs from the gastrointestinal tract may be decreased by giving activated charcoal. Repeated doses of charcoal over time may hasten elimination of some drugs that have been absorbed. Safeguard the patient's airway when employing gastric emptying or charcoal. Forced diuresis, peritoneal dialysis, haemodialysis or charcoal haemoperfusion have not been established as beneficial for an overdose of cefaclor.
: biconvex, capsule shape and coloured blue. CEFACLOR CD 375 mg is printed in black ink on the tablet.
Blister packs of 10. AUST R Number 77099
are sustained-release tablets intended for oral administration. Each tablet contains cefaclor monohydrate equivalent to 375 mg cefaclor anhydrous.
In addition, each tablet contains the following inactive ingredients: hypromellose, hydroxypropyl cellulose, lactose, colloidal anhydrous silica, magnesium stearate purified talc, titanium dioxide, polyethylene glycol 400, indigo carmine, iron oxide black, propylene glycol, methanol and isopropyl alcohol. Store below 25degC. Protect from moisture and light.
Apotex Pty Ltd 16 Giffnock Avenue Macquarie Park NSW 2113 Chemmart is a registered trade mark of Symbion Pty Ltd.
S4: Prescription Only Medicine.
9 December 2000