Metromox

Uses

Amoxicillin is used for the treatment of the following bacterial infections when caused by susceptible organisms:

• Respiratory tract, ENT infections: Acute and chronic bronchitis, pneumonia, otitis media, sinusitis, tonsillitis, pharyngitis & laryngitis, lobar & bronchopneumonia, chronic bronchial sepsis.
• Urinary tract infections: Pyelonephritis, cystitis and urethritis.
• Obstetric & gynaecological infections: Bacteriuria in pregnancy, septic abortion, intra-abdominal sepsis and puerperal sepsis.
• Gastro-intestinal infections: Typhoid and paratyphoid.
• Skin & soft tissue infections: Cellulitis, infected wounds and abscesses.
• Generalized infections: Septicemia, bacterial endocarditis, meningitis, peritonitis and osteomyelitis.
• Venereal infections: Gonorrhea and syphilis. Amoxicillin may also be used as prophylactic cover for patients at risk of developing endocarditis when undergoing dental surgery.

Metronidazole is used for:

• All forms of amoebiasis (intestinal and extra-intestinal disease including liver abscess and that of symptomless cyst passers)
• Trichomoniasis
• Giardiasis
• Bacterial vaginosis
• Acute ulcerative gingivitis
• Anaerobic infections including septicaemia, bacteraemia, peritonitis, brain abscess, necrotising pneumonia, osteomyelitis, puerperal sepsis, pelvic abscess, pelvic cellulitis etc.
• Anaerobically-infected leg ulcers and pressure sores
• Acute dental infections (e.g. acute pericoronitis and acute apical infections)
• Surgical prophylaxis (prevention of postoperative infections due to anaerobic bacteria, particularly species of bacteroides and anaerobic streptococci
• Chronic symptomatic peptic ulcer disease (as an agent of triple therapy to eradicate H. pylori-the most important aetiological factor of peptic ulcer)

Metromox is also used to associated treatment for these conditions: Acute Bacterial Sinusitis (ABS), Acute Otitis Media, Acute Otitis Media (AOM), Bacterial Infections, Community Acquired Pneumonia (CAP), Duodenal ulcer caused by helicobacter pylori, Genitourinary infections, Helicobacter Pylori Infection, Lower Respiratory Tract Infection (LRTI), Peptic Ulcer With H. Pylori Infection, Sinusitis, Skin and Subcutaneous Tissue Bacterial Infections, Urinary Tract Infection, Acute, uncomplicated Gonorrhea, Ear, nose, and throat infectionsAbscess, Intra-Abdominal, Acne Rosacea, Amebiasis, Anaerobic Infection, Bacteremia, Bacterial Endocarditis, Bacterial Peritonitis, Bacterial Vaginosis (BV), Balantidiasis, Bloodstream Infections, Bone and Joint Infections, Brain abscess, CNS Infection, Candidal Vulvovaginitis, Clostridium Difficile Infection (CDI), Empyema, Endometritis, Endomyometritis, Facial Rosacea, Giardiasis, Gynaecological infection, Helicobacter Pylori Infection, Infection, Bacteroides, Intraabdominal Infections, Lower Respiratory Infection, Lower respiratory tract infection bacterial, Lung Abscess, Meningitis, Mixed Vaginal Infections, Parasitic infection NOS, Periodontitis, Pneumonia, Postoperative Infections, Pouchitis, Septicemia bacterial anaerobic, Skin and Subcutaneous Tissue Bacterial Infections, Tetanus, Trichomonal Vaginitis, Trichomonas Vaginitis, Tubo-ovarian abscess, Urethritis, Vulvovaginitis, Asymptomatic Trichomoniasis, Entamoeba histolytica, Hepatic abscess, Refractory Sinusitis, Skin and skin-structure infections, Symptomatic Trichomoniasis, Asymptomatic Infections

How Metromox works

Amoxicillin competitively inhibits penicillin-binding protein 1 and other high molecular weight penicillin binding proteins. Penicillin bind proteins are responsible for glycosyltransferase and transpeptidase reactions that lead to cross-linking of D-alanine and D-aspartic acid in bacterial cell walls. Without the action of penicillin binding proteins, bacteria upregulate autolytic enzymes and are unable to build and repair the cell wall, leading to bacteriocidal action.

The exact mechanism of action of metronidazole has not been fully established, however, it is possible that an intermediate in the reduction of metronidazole which is only made by anaerobic bacteria and protozoa, binds deoxyribonucleic acid and electron-transport proteins of organisms, blocking nucleic acid synthesis. After administration, metronidazole enters cells by passive diffusion. Following this, ferredoxin or flavodoxin reduce its nitro group to nitro radicals. The redox potential of the electron transport portions of anaerobic or microaerophilic microorganisms renders metronidazole selective to these organisms, which cause nitro group reduction, leading to the production of toxic metabolites. These include N-(2-hydroxyethyl) oxamic acid and acetamide, which may damage DNA of replicating organisms.

Dosage

Metromox dosage

Ear/Nose/ThroatInfection (Mild to Moderate):

• Adult:500 mg every 12 hours or 250 mg every 8 hours
• Children:25 mg/kg/day in divided doses every 12 hours or 20 mg/kg/day in divided doses every 8 hours

Ear/Nose/ThroatInfection (Severe):

• Adult: 875 mg every 12 hours or 500 mg every 8 hours
• Children: 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours

Lower respiratory tractInfection (Mild/ Moderate/Severe):

• Adult: 875 mg every 12 hours or 500 mg every 8 hours
• Children: 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours

Skin/skin structureInfection (Mild/Moderate):

• Adult: 500 mg every 12 hours or 250 mg every 8 hours
• Children: 25 mg/kg/day in divided doses every 12 hours or 20 mg/kg/day in divided doses every 8 hours

Skin/skin structureInfection (Severe):

• Adult: 875 mg every 12 hours or 500 mg every 8 hours
• Children: 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours

Genitourinary tractInfection (Mild/ Moderate):

• Adult: 500 mg every 12 hours or 250 mg every 8 hours
• Children: 25 mg/kg/day in divided doses every 12 hours or 20 mg/kg/day in divided doses every 8 hours

Genitourinary tractInfection (Severe):

• Adult: 875 mg every 12 hours or 500 mg every 8 hours
• Children: 45 mg/kg/day in divided doses every 12 hours or 40 mg/kg/day in divided doses every 8 hours

Gonorrhea, Acute, uncomplicated ano-genital, and urethral infections in males and females:

• Adult: 3 g as single oral dose
• Prepubertal children: 50 mg/Kg/Amoxycillin, combined with 25 mg/kg Probenecid as a single dose. Since Probenecid is contraindicated in children under 2 years, do not use this regimen in these cases.

Tablet and Suspension:

Amoebic dysentery: Duration 5-10 Days;

• For Tablet: Adults- 750 mg t.i.d. Children- (7-10 years) 500 mg t.i.d. (3-7 years) 250 mg q.i.d. (1-3 years) 250 mg t.i.d.
• For Suspension: Adults- 800 mg t.i.d. Children- (7-10 years) 500 mg t.i.d. (3-7 years) 200 mg q.i.d. (1-3 years) 200 mg t.i.d.

Asymptomatic amoebiasis: Duration 5-10 Days;

• For Tablet: Adults- 500-750 mg t.i.d. Children- (7-10 years) 250-500 mg t.i.d. (3-7 years) 250 mg q.i.d. (1-3 years) 250 mg t.i.d.
• For Suspension: Adults- 500-800 mg t.i.d. Children- (7-10 years) 200-500 mg t.i.d.; (3-7 years) 200 mg q.i.d.; (1-3 years) 200 mg t.i.d.

Hepatic extraintestinal amoebiasis : Duration 5-10 Days (or 2days);

• For Tablet: Adults- 500-750 mg t.i.d.; Children- (7-10 years) 250-500 mg t.i.d.; (3-7 years) 250 mg q.i.d.; (1-3 years) 250 mg t.i.d.
• For Suspension: Adults- 500-800 mg t.i.d.; Children- (7-10 years) 200-500 mg t.i.d.; (3-7 years) 200 mg q.i.d.; (1-3 years) 200 mg t.i.d.

Giardiasis: Duration 3 Days;

• For Tablet: Adults- 2 g once daily; Children-(7-10 years) 1g once daily; (3-7 years) 750 mg once daily; (1-3 years) 500 mg once daily.
• For suspension: Adults- 2 g once daily; Children-(7-10 years) 1g once daily; (3-7 years) 800 mg once daily; (1-3 years) 500 mg once daily.

Trichomoniasis: Duration 7 Days;

• For Tablet: Adults- 250 mg t.i.d.; Children- (7-10 years) 100 mg t.i.d.; (3-7 years) 100 mg b.i.d.; (1-3 years) 50 mg t.i.d.
• For Suspension: Adults- 200 mg t.i.d.; Children- (7-10 years) 100 mg t.i.d.; (3-7 years) 100 mg b.i.d.; (1-3 years) 50 mg t.i.d.

Trichomoniasis: Duration 1 Day;

• For Tablet: Adults- 2 g single dose;
• For Suspension: Adults- 2 g single dose;

Vincent's infection (Ulceration of mucous membrane of respiratory tract & mouth): Duration 3 Days;

• For Tablet: Adults- 250 mg t.i.d. or 500 mg b.i.d; Children- (7-10 years) 100 mg t.i.d.; (3-7 years) 100 mg b.i.d.; (1-3 years) 50 mg t.i.d.
• For Suspension: Adults- 200 mg t.i.d. or 500 mg b.i.d; Children- (7-10 years) 100 mg t.i.d.; (3-7 years) 100 mg b.i.d.; (1-3 years) 50 mg t.i.d.

Periodontal infection: Duration 3 Days;

• For Tablet: Adults- 250 mg t.i.d.; Children- (7-10 years) 100 mg t.i.d.; (3-7 years) 100 mg b.i.d.; (1-3 years) 50 mg t.i.d.
• For Suspension: Adults- 200 mg t.i.d.; Children- (7-10 years) 100 mg t.i.d.; (3-7 years) 100 mg b.i.d.; (1-3 years) 50 mg t.i.d.

Severe dental infection: Duration 3 Days;

• For Tablet: Adults- 500 mg t.i.d.; Children- (7-10 years) 100 mg t.i.d.; (3-7 years) 100 mg b.i.d.; (1-3 years) 50 mg t.i.d.
• For Suspension: Adults- 500 mg t.i.d.; Children- (7-10 years) 100 mg t.i.d.; (3-7 years) 100 mg b.i.d.; (1-3 years) 50 mg t.i.d.

Anaerobic infection: Duration 7 Days;

• For Tablet: Adults- 500 mg t.i.d.; Children- 7.5 mg/kg body weight t.i.d.
• For Suspension: Adults- 500 mg t.i.d.; Children- 7.5 mg/kg body weight t.i.d.

Postoperative anaerobic infection (specially in operation abdominal or gynecological surgery): Duration 7 Days;

• For Tablet: Adults- 500 mg t.i.d. before and after operation; Children- 7.5 mg/kg body weight t.i.d.
• For Suspension: Adults- 500 mg t.i.d. before and after operation; Children- 7.5 mg/kg body weight t.i.d.

Bacterial vaginitis: Duration 7 Days;

• For Tablet: Adults- 500 mg b.i.d.
• For Suspension: Adults- 500 mg b.i.d.

Leg ulcers: Duration 1 Day;

• For Tablet: Adults- 2 g as a single dose
• For Suspension: Adults- 2 g as a single dose

Pressure sores: Duration 7 Days;

• For Tablet: Adults- 500 mg t.i.d.
• For Suspension: Adults- 500 mg t.i.d.

H. pylori infection: Duration 7 Days;

• For Tablet: Adults- 500 mg b.i.d
• For Suspension: Adults-500 mg b.i.d

Antibiotic Associated Pseudomembranus colitis: Duration 7 Days;

• For Tablet: Adults- 500 mg b.i.d
• For Suspension: Adults- 500 mg b.i.d

Vaginal Gel:

The recommended dose is one applicator full of Metronidazole GEL (approximately 5 grams containing approximately 37.5 mg of Metronidazole) intravaginally once or twice a day for 5 days. For once a day dosing, Metronidazole GEL should be administered at bedtime.

Suppository:

Anaerobic infections:

• Adult: 1 g 8 hrly for 3 days, then 12 hrly thereafter until oral medication is possible.
• Child: 5-10 yr 500 mg. All doses to be given 8 hrly for 3 days, then 12 hrly thereafter until oral medication is possible.

Prophylaxis of postoperative anaerobic bacterial infections:

• Adult: 1 g 2 hr before surgery, repeated 8 hrly for 3 days, then 12 hrly thereafter until oral medication is possible.
• Child: 5-10 yr 500 mg 2 hr before surgery, repeated 8 hrly for 3 days, then 12 hrly thereafter until oral medication is possible.

IV Infusion:

Metronidazole injection should be infused intravenously at an approximate rate of 5 ml/min. Oral medication should be substituted as soon as feasible. Treatment for 7 days should be satisfactory for most patients, but the physician might decide to prolong treatment.

• For bacterial infections: Adults: 500 mg (100 ml) 8 hourly. Children: 7.5 mg/kg (1.5 ml/kg) 8 hourly.
• For treatment before and during surgery: Adults: 500 mg (100 ml) shortly before operation, repeated 8 hourly. Children: 7.5 mg/kg (1.5 ml/kg) 8 hourly

Suspension: Shake the bottle well before adding water. Then add 12 tea spoonful (60 ml) of boiled and cooled water to the bottle and shake well to make 100 ml suspension.

Amoxycillin 500 mg Injection:

• Intramuscular : Add 2.5 ml water for injection to Amoxycillin 500 mg injection vial.
• Intravenous : Dissolve Amoxycillin 500 mg injection in 10 ml water for injection.

Side Effects

Side effects are mild, rare and infrequent. As with other penicillins, it may induce diarrhea, indigestion or skin rashes that usually stop during treatment and rarely calls for discontinuation of therapy.

Side effects of Metronidazole include gastrointestinal discomfort, nausea, coated tongue, dryness of mouth and unpleasant metallic or bitter taste, headache, pruritus and skin rashes and less frequently, vertigo, depression, insomnia, drowsiness, urethral discomfort, and darkening of the urine. Occasionally there may be temporary moderate leucopenia. Peripheral neuropathy has been reported in patients on prolonged therapy.

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.

LD50 information

The oral LD50 of metronidazole in rats is 5000 mg/kg

Overdose information

Adverse effects that may be exaggerated with an overdose include peripheral neuropathy, central nervous system toxicity, seizures, disulfiram-like effect (if combined with alcohol) dark urine, a metallic taste in the mouth, nausea, epigastric discomfort, and vertigo, in addition to neutropenia. There is no specific antidote for metronidazole overdose. Symptomatic and supportive treatment should be employed in addition to the administration of activated charcoal to remove the unabsorbed drug from the gastrointestinal tract. In addition to the above measures, contact the local poison control center for updated information on the management of a metronidazole overdose.

Precaution

In renal impairment, the excretion of antibiotic will be delayed and depending on the degree of impairment it may be necessary to reduce the total daily dose.

Metronidazole should not be used in patients with blood dyscrasia. It is suggested that it should not be given in the first three months of pregnancy. When given in conjunction with alcohol, Metronidazole may provoke a disulphiram like effect.

Interaction

The simultaneous use of Amoxicillin and an oral contraceptive might cause breakthrough bleeding or pregnancy on rare occasions. Concurrent administration of probenecid delays the excretion of Amoxicillin.

Metronidazole interacts with warfarin, nicoumalone, phenytoin, phenobarbitone, fluorouracil, disulfiram, lithium, cimetidine etc.

Volume of Distribution

The central volume of distribution of amoxicillin is 27.7L.

Metronidazole is widely distributed throughout the body and various body fluids. They include the bile, saliva, breastmilk, cerebrospinal fluid, and the placenta. Steady-state volume distribution of metronidazole in adults ranges from 0.51 to 1.1 L/kg. It attains 60 to 100% of plasma concentrations in various tissues, such as the central nervous system, however, is not measured in high concentrations in the placental tissue.

Elimination Route

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

After the intravenous infusion of a 1.5g dose, peak concentration was reached within 1 hour and was peak level of 30-40 mg/L. When a multiple-dose regimen of 500mg three times a day administered intravenously, steady-state concentrations were achieved within about 3 days and peak concentration was measured at 26 mg/L. When administered orally in the tablet form, metronidazole is absorbed entirely absorbed, showing a bioavailability of greater than 90%. One resource indicates that Cmax after a single oral dose of 500mg metronidazole ranges from 8 to 13 mg/L, with a Tmax of 25 minutes to 4 hours. The AUC following a single 500mg oral dose of metronidazole was 122 ± 10.3 mg/L • h.

A note on the absorption of topical preparations

Insignificant percutaneous absorption of metronidazole occurs after the application of 1% metronidazole cream topically. Healthy volunteers applied one 100 mg dose of 14C-labelled metronidazole 2% cream to unbroken skin. After 12 hours, metronidazole was not detected in the plasma. Approximately 0.1% to 1% of the administered metronidazole was measured in the urine and feces.

Half Life

The half life of amoxicillin is 61.3 minutes.

The elimination half-life of metronidazole is 7.3 ± 1.0 after a single 500mg IV dose in healthy subjects. Another resource indicates that the elimination half-life for metronidazole ranges from 6 to 10 hours.

Clearance

The mean clearance of amoxicillin is 21.3L/h.

Dose adjustments may be required in patients with hepatic impairment, as clearance is impaired in these patients. The clearance of metronidazole in the kidneys is estimated at 10 mL/min/1.73 m2. The total clearance from serum is about 2.1 to 6.4 L/h/kg.

Elimination Route

125mg to 1g doses of amoxicillin are 70-78% eliminated in the urine after 6 hours.

Metronidazole and metabolites are 60 to 80% eliminated in the urine, and 6-15% excreted in the feces.

Pregnancy & Breastfeeding use

Because of its lack of teratogenicity, Amoxicillin can beused safely throughout pregnancy at the normal adult dose. The small amount of Amoxicillin secreted in maternal milk rarely causes problem in the infant. It can therefore be used safely during lactation in most instances.

Not recommended during first & later trimesters. Breast feeding should be delayed until 48 hours after discontinuing metronidazole in the mother.

Contraindication

Amoxicillin is contraindicated for patients hypersensitive to penicillin, infectious mononucleosis, neonatal period or babies born of mothers hypersensitive to penicillin

Metronidazole is contraindicated in patients with prior history of hypersensitivity to Metronidazole or other Nitroimidazole derivatives.

Acute Overdose

If encountered, gastro-intestinal symptoms and disturbance of the fluid and electrolyte balance may be evident. They may be treated symptomatically and supportive with attention to the water/ electrolyte balance. In the absence of an adequate fluid intake and urinary output, crystalluria is a possibility and the antibiotic may be removed from the circulation by haemodialysis. Oral administration can cause gastro intestinal symptoms such as transient diarrhoea, nausea and colic which are dose related and a result of local irritation not toxicity.

Storage Condition

Store in a cool & dry place protected from light. Amoxicillin suspension and drops should be freshly prepared, stored in a cool dry place preferably in a refrigerator. Reconstituted suspension and drops should be used within 5 days if kept at room temperature or within 7 days if kept in a refrigerator.

Store in a cool and dry place. Protect from light and moisture. Keep out of the reach of children

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