Pharothrocin Dosage

How do you administer this medicine?

Dosage of Pharothrocin in details

The dose of a drug and dosage of the drug are two different terminologies. Dose is defined as the quantity or amount of medicine given by the doctor or taken by the patient at a given period. Dosage is the regimen prescribed by the doctor about how many days and how many times per day the drug is to be taken in specified dose by the patient. The dose is expressed in mg for tablets or gm, micro gm sometimes, ml for syrups or drops for kids syrups. The dose is not fixed for a drug for all conditions, and it changes according to the condition or a disease. It also changes on the age of the patient.

For the treatment of severe infections in adults and pediatric patients, the recommended intravenous dose of Pharothrocin lactobionate is 15 to 20 mg/kg/day. Higher doses, up to 4 g/day, may be given for severe infections.

Administration of doses of ≥ 4 g/day may increase the risk for the development of Pharothrocin-induced hearing loss in elderly patients, particularly those with reduced renal or hepatic function. Pharothrocin-IV (Pharothrocin lactobionate for injection, USP) must be administered by continuous or intermittent intravenous infusion only. Due to the irritative properties of Pharothrocin, IV push is an unacceptable route of administration.

Continuous infusion of Pharothrocin lactobionate is preferable due to the slower infusion rate and lower concentration of Pharothrocin; however, intermittent infusion at six hour intervals is also effective.

Intravenous Pharothrocin should be replaced by oral Pharothrocin as soon as possible.

For slow continuous infusion: The final diluted solution of Pharothrocin lactobionate is prepared to give a concentration of 1 g per liter

(1 mg/mL). For intermittent infusion: Administer one-fourth the total daily dose of Pharothrocin lactobionate by intravenous infusion in 20 to 60 minutes at intervals not greater than every six hours. The final diluted solution of Pharothrocin lactobionate is prepared to give a concentration of 1 to 5 mg/mL. No less than 100 mL of IV diluent should be used. Infusion should be sufficiently slow to minimize pain along the vein.

For treatment of acute pelvic inflammatory disease caused by N. Gonorrhoeae, in female patients hypersensitive to penicillins, administer 500 mg Pharothrocin lactobionate every six hours for three days, followed by oral administration of 250 mg Pharothrocin stearate or base every six hours for seven days.

For treatment of Legionnaires' Disease: Although optimal doses have not been established, doses utilized in reported clinical data were

1 to 4 grams daily in divided doses. Administration of doses of ≥ 4 g/day may increase the risk for the development of Pharothrocin-induced hearing loss in elderly patients, particularly those with reduced renal or hepatic function.

In the treatment of Group A beta-hemolytic streptococcal infections of the upper respiratory tract (e.g., tonsillitis or pharyngitis), the therapeutic dosage of Pharothrocin should be administered for ten days. The American Heart Association suggests a dosage of 250 mg of Pharothrocin orally, twice a day in long-term prophylaxis of streptococcal upper respiratory tract infections for the prevention of recurring attacks of rheumatic fever in patients allergic to penicillin and sulfonamides.

Preparation of Solution:
  1. PREPARE THE INITIAL SOLUTION OF ERYTHROCIN™ LACTOBIONATE-IV BY ADDING 10 ML OF STERILE WATER FOR INJECTION, USP, TO THE 500 MG VIAL. Use only Sterile Water for Injection, USP, as other diluents may cause precipitation during reconstitution. Do not use diluents containing preservatives or inorganic salts.

    After reconstitution, each mL contains 50 mg of Pharothrocin activity. The initial solution is stable at refrigerator temperature for two weeks, or for 24 hours at room temperature.

  2. ADD THE INITIAL DILUTION TO ONE OF THE FOLLOWING DILUENTS BEFORE ADMINISTRATION to give a concentration of 1 g of Pharothrocin activity per liter (1 mg/mL) for continuous infusion or 1 to 5 mg/mL for intermittent infusion: 0.9% SODIUM CHLORIDE INJECTION, USP; LACTATED RINGER'S INJECTION, USP; NORMOSOL™-R.




Neut™ (4% sodium bicarbonate, Hospira) must be added to these solutions so that their pH is in the optimum range for Pharothrocin lactobionate stability. Acidic solutions of Pharothrocin lactobionate are unstable and lose their potency rapidly. A pH of at least 5.5 is desirable for the final diluted solution of Pharothrocin lactobionate.

No drug or chemical agent should be added to an Pharothrocin lactobionate-IV fluid admixture unless its effect on the chemical and physical stability of the solution has first been determined.


The final diluted solution of Pharothrocin lactobionate should be completely administered within 8 hours, since it is not suitable for storage.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

How supplied

Pharothrocin-IV (Pharothrocin lactobionate for injection, USP) is supplied as a sterile, lyophilized powder in packages of ten vials (NDC 0409-6482-01), each vial containing the equivalent of 500 mg of Pharothrocin. Store at 20 to 25°C (68 to 77°F).


4. Committee on Rheumatic Fever and Infective Endocarditis of the Council on Cardiovascular Disease of the Young: Prevention of Rheumatic Fever, Circulation 70(6):1118A-1122A, December 1984.

5. Committee on Rheumatic Fever and Infective Endocarditis of the Council on Cardiovascular Disease of the Young: Prevention of Bacterial Endocarditis, Circulation 70(6):1123A-1127A, December 1984.

Hospira, Inc., Lake Forest, IL 60045 USA. Revised: 01/2013

What other drugs will affect Pharothrocin?

Many drugs can interact with Pharothrocin. Below is just a partial list. Tell your doctor if you are using:

  • alfentanil (Alfenta);
  • bromocriptine (Parlodel);
  • cilostazol (Pletal);
  • colchicine (Colcrys);
  • cyclosporine (Sandimmune, Gengraf, Neoral);
  • digoxin (Lanoxin);
  • methylprednisolone (Medrol);
  • sildenafil (Viagra);
  • tacrolimus (Prograf);
  • theophylline (Elixophyllin, Theo-24, Theochron, Uniphyl);
  • vinblastine (Velban);
  • alprazolam (Xanax) or triazolam (Halcion);
  • a blood thinner such as warfarin (Coumadin, Jantoven);
  • carbamazepine (Carbatrol, Equetro, Tegretol), phenytoin (Dilantin), or valproic acid (Depakene, Stavzor);
  • atorvastatin (Lipitor, Caduet), lovastatin (Mevacor, Altoprev, Advicor), or simvastatin (Zocor, Simcor, Vytorin);
  • heart or blood pressure medicine such as amlodipine (Norvasc, Caduet, Exforge, Lotrel, Tekamlo, Tribenzor, Twynsta, Amturnide), diltiazem (Cardizem, Cartia, Dilacor, Diltia, Diltzac, Taztia, Tiazac), or verapamil (Calan, Covera, Isoptin, Verelan);
  • a heart rhythm medication such as amiodarone (Cordarone, Pacerone), disopyramide (Norpace), dofetilide (Tikosyn), dronedarone (Multaq), flecainide (Tambocor), ibutilide (Corvert), mexiletine (Mexitil), procainamide (Procan, Pronestyl), propafenone, (Rythmol), quinidine (Quin-G), sotalol (Betapace), and others; or
  • any other antibiotics.

This list is not complete and there are many other drugs that can interact with Pharothrocin. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.

Pharothrocin interactions

Interactions are the effects that happen when the drug is taken along with the food or when taken with other medications. Suppose if you are taking a drug Pharothrocin, it may have interactions with specific foods and specific medications. It will not interact with all foods and medications. The interactions vary from drug to drug. You need to be aware of interactions of the medicine you take. Most medications may interact with alcohol, tobacco, so be cautious.


Pharothrocin use in patients who are receiving high doses of theophylline may be associated with an increase in serum theophylline levels and potential theophylline toxicity. In case of theophylline toxicity and/or elevated serum theophylline levels, the dose of theophylline should be reduced while the patient is receiving concomitant Pharothrocin therapy.

There have been published reports suggesting that when oral Pharothrocin is given concurrently with theophylline there is a decrease in Pharothrocin serum concentrations of approximately 35%. The mechanism by which this interaction occurs is unknown. The decrease in Pharothrocin concentrations due to co-administration of theophylline could result in subtherapeutic concentrations of Pharothrocin.

Hypotension, bradyarrhythmias, and lactic acidosis have been observed in patients receiving concurrent verapamil, belonging to the calcium channel blockers drug class.

Concomitant administration of Pharothrocin and digoxin has been reported to result in elevated digoxin serum levels.

There have been reports of increased anticoagulant effects when Pharothrocin and oral anticoagulants were used concomitantly. Increased anticoagulation effects due to interactions of Pharothrocin with oral anticoagulants may be more pronounced in the elderly.

Pharothrocin is a substrate and inhibitor of the 3A isoform subfamily of the cytochrome p450 enzyme system (CYP3A). Coadministration of Pharothrocin and a drug primarily metabolized by CYP3A may be associated with elevations in drug concentrations that could increase or prolong both the therapeutic and adverse effects of the concomitant drug. Dosage adjustments may be considered, and when possible, serum concentrations of drugs primarily metabolized by CYP3A should be monitored closely in patients concurrently receiving Pharothrocin.

The following are examples of some clinically significant CYP3A based drug interactions. Interactions with other drugs metabolized by the CYP3A isoform are also possible. The following CYP3A based drug interactions have been observed with Pharothrocin products in post-marketing experience:


Post-marketing reports indicate that co-administration of Pharothrocin with ergotamine or dihydroergotamine has been associated with acute ergot toxicity characterized by vasospasm and ischemia of the extremities and other tissues including the central nervous system. Concomitant administration of Pharothrocin with ergotamine or dihydroergotamine is contraindicated.

Triazolobenzodiazepines (such as triazolam and alprazolam) and related benzodiazepines

Pharothrocin has been reported to decrease the clearance of triazolam and midazolam, and thus, may increase the pharmacologic effect of these benzodiazepines.

HMG-CoA Reductase Inhibitors

Pharothrocin has been reported to increase concentrations of HMG-CoA reductase inhibitors (e.g., lovastatin and simvastatin). Rare reports of rhabdomyolysis have been reported in patients taking these drugs concomitantly.

Sildenafil (Viagra)

Pharothrocin has been reported to increase the systemic exposure (AUC) of sildenafil. Reduction of sildenafil dosage should be considered.

There have been spontaneous or published reports of CYP3A based interactions of Pharothrocin with cyclosporine, carbamazepine, tacrolimus, alfentanil, disopyramide, rifabutin, quinidine, methyl-prednisolone, cilostazol, vinblastine, and bromocriptine.

Concomitant administration of Pharothrocin with cisapride, pimozide, astemizole, or terfenadine is contraindicated.

In addition, there have been reports of interactions of Pharothrocin with drugs not thought to be metabolized by CYP3A, including hexobarbital, phenytoin, and valproate.

Pharothrocin has been reported to significantly alter the metabolism of the nonsedating antihistamines terfenadine and astemizole when taken concomitantly. Rare cases of serious cardiovascular adverse events, including electrocardiographic QT/QTc interval prolongation, cardiac arrest, torsades de pointes, and other ventricular arrhythmias, have been observed. In addition, deaths have been reported rarely with concomitant administration of terfenadine and Pharothrocin.

There have been post-marketing reports of drug interactions when Pharothrocin was coadministered with cisapride, resulting in QT prolongation, cardiac arrhythmias, ventricular tachycardia, ventricular fibrillation, and torsades de pointes, most likely due to the inhibition of hepatic metabolism of cisapride by Pharothrocin. Fatalities have been reported..


Colchicine is a substrate for both CYP3A4 and the efflux transporter P-glycoprotein (P-gp). Pharothrocin is considered a moderate inhibitor of CYP3A4. A significant increase in colchicine plasma concentration is anticipated when co-administered with moderate CYP3A4 inhibitors such as Pharothrocin. If co-administration of colchicine and Pharothrocin is necessary, the starting dose of colchicine may need to be reduced, and the maximum colchicine dose should be lowered. Patients should be monitored for clinical symptoms of colchicine toxicity.

Drug/Laboratory Test Interactions

Pharothrocin interferes with the fluorometric determination of urinary catecholamines.



  1. DailyMed. "ERYTHROMYCIN: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". (accessed September 17, 2018).
  2. FDA/SPL Indexing Data. "63937KV33D: The UNique Ingredient Identifier (UNII) is an alphanumeric substance identifier from the joint FDA/USP Substance Registration System (SRS).". (accessed September 17, 2018).
  3. MeSH. "Protein Synthesis Inhibitors". (accessed September 17, 2018).


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Information checked by Dr. Sachin Kumar, MD Pharmacology

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