Erythromycin dosing

Erythromycin is a substrate for the cytochrome P450 (CYP 450) 3A4 isoenzyme. Once bound to CYP 3A, erythromycin stimulates its own metabolism via demethylation and oxidation to nitroalkane metabolites. These nitroalkane metabolites appear to form stable complexes with the iron of the CYP 3A4 isoenzyme, decreasing its functional capacity. Depending upon the erythromycin dose and duration of therapy, CYP 3A4 activity could be inhibited to undetectable activity and serves as the basis of erythromycin-associated metabolic-based drug-drug interactions. 

Increase in theophylline serum concentrations is generally not more than 25% after erythromycin. Dose reduction by 25% might be appropriate. Use of other antibiotics should be considered, especially if troleandomycin is used. 

Twelve healthy subjects were given lisuride 200 micrograms orally or 50 micrograms as a 30 minute intravenous infusion after taking erythromycin [dose unknown] twice daily for 4 days. Preliminary results showed that erythromycin did not significantly modify either the pharmacokinetics or the pharmacodynamics of the lisuride. ... 

Maintenance doses widely vary among patients (e.g., from 1 to 20 mg/day for warfarin), and are influenced by diet (variable vitamin K intake) and medications that affect coumarin metabolism (decreased drug clearance e.g., cotrimoxazole, amiodarone, erythromycin increased clearance e.g., barbiturates, carbamaze-pine, rifampin). Thus, regular monitoring is needed... 

Theoretically buprenorphine metabolism could be inhibited by itraconazole, ketoconazole, grapefruit juice, and erythromycin or any other CYP3A4 inhibitor the effects may be greater than expected for the dose of buprenorphine being given may need to decrease buprenorphine dose. 

Although tetracycline, doxycycline, and minocycline are the most commonly prescribed oral antibiotics for acne, erythromycin and clindamycin are appropriate second-line agents for use when patients cannot tolerate or have developed resistance to tetracycline or its derivatives.3 See Table 62-3 for antibiotic dosing guidelines. 

Erythromycin Tablets 250, 500 mg 500 mg twice daily with food Maintenance dose 500 mg daily Gl intolerance, drug interactions... 

Children with SCD should receive prophylactic penicillin until at least the age of 5 years, even if they have been immunized appropriately with PCV 7 against pneumococcal infections. Penicillin V potassium typically is initiated at age 2 months with a dose of 125 mg orally twice daily until age 3 years and then 250 mg orally twice daily until 5 years of age. The intramuscular use of benzathine penicillin 600,000 units every 4 weeks from age 6 months to 6 years is also an option for non-compliant patients. Penicillin-allergic patients may receive erythromycin 10 mg/kg twice daily. Penicillin prophylaxis usually is not continued in children over the age of 6 years but may be considered in patients with a history of invasive pneumococcal infection or surgical splenectomy.6,18-20... 

Erythromycin- sulfisoxazole 50 mg/kg per day of erythromycin component in 3 4 doses Nausea, vomiting, abdominal pain, diarrhea, rash SS Many drug interactions (like clarithromycin), contraindicated in children under 2 months increasing pneumococcal resistance... 

Other FDA-approved antibiotics for ABRS not included in the Sinus and Allergy Health Partnership or AAP guidelines cefaclor, cefprozil, cefixime, ciprofloxacin, erythromycin, loracarbef. cMaximum dose not to exceed adult dose. 

The WHO and CDC recommended treatment regimens are shown in Table 77-5.37 There has been some debate about a suitable dosage of ciprofloxacin in the treatment of chancroid. Though the CDC recommends 500 mg orally three times daily, the WHO supports a single 500-mg oral dose. Ciprofloxacin has demonstrated an acceptable cure rate for a single dose (92%) when compared to erythromycin (91%). 

Stuer et al. [46] evaluated the presence of the 25 most used pharmaceuticals in the primary health sector in Denmark (e.g., paracetamol, acetyl salicylic acid, diazepam, and ibuprofen). They compared PECs with experimental determinations and they conclude that measured concentrations were in general within a factor of 2-5 of PECs. Carballa et al. [45] also determined PECs for pharmaceuticals (17), musk fragrances (2) and hormones (2) in sewage sludge matrix. For that purpose they used three different approaches (1) extrapolation of the per capita use in Europe to the number of Spanish inhabitants for musk fragrances (2) annual prescription items multiplied by the average daily dose for pharmaceuticals and (3) excretion rates of different groups of population for hormones. They indicated that these PECs fitted with the measured values for half of them (carbamazepine, diazepam, ibuprofen, naproxen, diclofenac, sulfamethoxazole, roxithromycin, erythromycin, and 17a-ethiny I e strad iol). 

In some patients SIBO is caused by intestinal stasis secondary to motility defects, and the restoration of normal intestinal motility may represent an effective approach. Prokinetic agents have been shown to improve intestinal motility [ 15,16], and the use of this therapeutic approach has been shown to be effective in patients with scleroderma, low-dose octreotide proved to be useful in the reduction of bacterial overgrowth [17]. Unfortunately, cisapride was recently removed from the market due to car-diotoxicity, and, apart from an erythromycin analog without antibiotic effects which showed no effects in rats [18],... 

Erythromycin has efficacy similar to tetracycline, but it induces higher rates of bacterial resistance. Resistance may be reduced by combination therapy with benzoyl peroxide. Erythromycin can be used for patients who require systemic antibiotics but cannot tolerate tetracyclines, or those who acquire bacterial resistance to tetracyclines. The usual dose is 1 g/day with meals to minimize GI intolerance. 

Trimethoprim-sulfamethoxazole (or trimethoprim alone) is a second-line oral agent that may be used for patients who do not tolerate tetracyclines and erythromycin or in cases of resistance to these antibiotics. The adult dose is usually 800 mg sulfamethoxazole and 160 mg trimethoprim twice daily. 

Antibiotics shorten the duration of diarrhea, decrease the volume of fluid lost, and shorten the duration of the carrier state (see Table 39-3). A single dose of oral doxycycline is the preferred agent. In children younger than 7 years of age, trimethoprim-sulfamethoxazole, erythromycin, and furazolidone can be used. In areas of high tetracycline resistance, fluoroquinolones are effective. 

Amoxicillin Erythromycin 500 mg three times daily 40-50 mg/kg/day divided in three doses 10 days 10 days... 

Erythromycin base 50 mjykjy day orally in four divided doses for 14 days6... 

Didoxadllin 25-50 mg/kg in four divided doses Cephalexin 25-50 mg/kg in four divided doses Clindamycin 10-30 mg/kg/day in three to four divided doses0 Penicillin VK 25,000-90,000 units/kg in four divided doses Clindamycin 10-30 mg/kg in three to four doses0 Erythromycin 30-50 mg/kg in four divided doses0... 

Sildenafil doses should be decreased when any potent cytochrome P450 3A4 inhibitor is used (e g., cimetidine, erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and saquinavir). Vardenafil doses vary accordingto which agent is used (2.5 mg q 72 h for ritonavir, 2.5 mg q 24 h for indinavir, ketoconazole 400 mg daily, and itraconazole 400 mg daily and 5 mg q 24 h for ketoconazole 200 mg daily, itraconazole200 mg daily, and erythromycin). Tadalafil doses are reduced only when it is used with the most potent cytochrome P450 3A4 inhibitors (e g., ketoconazole or ritonavir). 

Maximum levels of erythromycin in serum are obtained in 1 to 2 hours after a single dose. 

The U. S. Dispensatory26 reports maximum serum levels of 0.2 ijg./ml. 1 hour after administration of a 250 mg. dose, 0.6 (ig./ml. 2 hours after a 500 mg. dose, and 1.2 ug./ml. 2 hours after a 1 g. dose. Higher blood levels are achieved on a multiple dosage schedule. Since it is acid labile, a resistant coating is used in tablet formulations to overcome the deleterious effect of gastric fluid on erythromycin base or the stearate salt is prepared which does not dissolve readily in the stomach. 

It can be seen in the above prescription that age of the child is just two months, and one teaspoonful (containing 200 mg/5 mL) three times daily appears to be high. Therefore the dose has to be lowered. The usual adult dose of erythromycin is 400 mg every six hours. In the present problem, Fried s Equation will be used as follows ... 

For patients receiving weak CYP3A4 inhibitors (eg, erythromycin, saquinavir, verapamil, fluconazole), reduce the starting dose to 25 mg once daily. 

Dosage adjustment - Consider a starting dose of 25 mg in the following patients Older than 65 years of age, hepatic impairment, severe renal impairment, and concomitant use of potent cytochrome P450 3A4 inhibitors (eg, erythromycin, ketoconazole, itraconazole, saquinavir). 

Concomitant mecf/caf/ons - The dosage of vardenafil may require adjustment in patients receiving certain CYP3A4 inhibitors. For ritonavir, do not exceed a single dose of 2.5 mg vardenafil in a 72-hour period. For indinavir, ketoconazole 400 mg/day, and itraconazole 400 mg/day, do not exceed a single dose of 2.5 mg vardenafil in a 24-hour period. For ketoconazole 200 mg/day, itraconazole 200 mg/day, and erythromycin, do not exceed a single dose of 5 mg vardenafil in a 24-hour period. 

A4 inhibitors - Patients receiving cytochrome P450 3A4 inhibitors, such as macrolide antibiotics (erythromycin and clarithromycin), antifungal agents (ketoconazole, itraconazole, and miconazole), or cyclosporine or vinblastine should not receive doses of tolterodine greater than 1 mg twice/day (greater than 2 mg/day for ER capsules). 

Cimetidine, erythromycin, and dextropropoxyphene had no effect on the pharmacokinetics of MHD. Results with warfarin show no evidence of interaction with either single or repeated doses of oxcarbazepine. 

Acute otitis media 50 mg/kg/day erythromycin and 150 mg/kg/day (to a maximum of 6 g/day) sulfisoxazole. Give in equally divided doses 4 times daily for 10 days. Administer without regard to meals. 

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