Antimicrobial dosage

Antimicrobial dosage regimens are designed in one of two ways either to maximize the plasma concentration or to provide a plasma concentration above the MIC for most of the interdosing interval (Vogelman et al 1988). 

Liquid Dosage Forms. Simple aqueous solutions, symps, elixirs, and tinctures are prepared by dissolution of solutes in the appropriate solvent systems. Adjunct formulation ingredients include certified dyes, flavors, sweeteners, and antimicrobial preservatives. These solutions are filtered under pressure, often using selected filtering aid materials. The products are stored in large tanks, ready for filling into containers. QuaUty control analysis is then performed. 

What antimicrobial therapy would you recommend Include drug, dosage, route, interval, and duration of therapy. 

Absorption of antimicrobial agents such as fluoroquinolones and tetracyclines that can be bound by divalent and trivalent cations potentially could be compromised by administration with EN formulas containing these cations. The fluoroquinolones (e.g., levofloxacin and ciprofloxacin) have been best studied in this regard, and results of studies are not consistent. Mechanisms for an interaction between fluoroquinolones and EN formulas other than chelation by cations have been postulated.40 Some institutions hold tube feedings for 30 to 60 minutes or more before and after enteral dosages of fluoroquinolones. Because ciprofloxacin absorption has been shown to be decreased with jejunal administration, this drug probably should not be given by jejunal tube.41... 

The availability of unpreserved and preserved dosage forms is considered. Mention is made of formulation changes necessitated by multidose products. The need for adequate antimicrobial preservative efficacy can be discussed if this was an issue during product development. 

Serum bactericidal titers may be useful only when the causative organisms are moderately susceptible to antimicrobials, when less well-established regimens are used, or when response to therapy is suboptimal and dosage escalation is considered. 

All preservative systems for both parenteral and nonsterile dosage forms should meet the 3 log reduction at 14 days for bacteria, that is, USP category I requirements. Both EP and BP Antimicrobial Effectiveness Testing would be run only if specially requested by the marketing group. 

USP 24 Testing Chapters (51) Antimicrobial Effectiveness Testing, (61) Microbial Limit Tests and (71) Sterility Tests, United States Pharmacopeial Convention, Inc., Rockville, MD, 2000. USP 24 Informational Chapters (1116) Microbiological Evaluation of Clean Rooms and other Controlled Environments, (1111) Microbiological Attributes of Pharmaceutical Articles, (1151) Pharmaceutical Dosage Forms, (1225) Validation of Compendial Methods, and (1231) Water for Pharmaceutical Purposes, United States Pharmacopeial Convention, Inc., Rockville, MD, 2000. 

Table 51-5 Antimicrobial Agents that Require Dosage Adjustment or Are Contraindicated in Patients with Renal or Hepatic Impairment. ...

Antiseborrheal agents Coal tar, 0.5-5% shampoo, dosage varies consult product labeling Denorex Therapeutic, Ionil T Plus, Pentrax 5%, various generic Tar derivatives inhibit epidermal proliferation and may possess antipruritic and antimicrobial activity. 

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