Tetracyclines, specific agents

Dahl EL, Shock JL, Shenai BR et al (2006) Tetracyclines specifically target the apicoplast of the malaria parasite Plasmodium falciparum. Antimicrob Agents Chemother 50(9) 3124-3131... 

Some of the newer tetracycline derivatives such as doxycycline may be used to overcome bacterial strains that are resistant to the traditional drugs.16 Currently, tetracyclines are used to treat specific infections relating to such bacilli as Chlamydia, Rickettsia, and certain spirochetes (see Table 33-5). Tetracyclines may also be used as alternative agents in treating bacterial strains... 

A variety of medical conditions cause water retention as the result of ADH excess. Unfortunately, specific ADH antagonists are available only for investigational purposes. Two nonselective agents, lithium and demeclocycline (a tetracycline derivative), are of limited use in some situations. 

Susceptibility designations are based on achievable plasma concentrations and do not take preferential drug accumulation at specific sites into account most antimicrobial agents are eliminated by the kidneys, achieving concentraflons in urine that are hundreds of times higher than those in plasma tetracyclines accumulate in pneumonic limg tissue. 

Antibiotics ate useful only in curtain specific infections, e.g. cholera and severe bacillary dysentiy. which are treated with tetracycline. The quinolones (Chapter 37) are more recent agents that seem to be effective against most important diarriioeal pathogens. 

Poly(N-vinyl-pyrrolidone), or PNVP, is a biocompatible, water-soluble (JJ ) polymer that has previously been used as a synthetic blood plasma extender, as a component of soft contact lenses, and in a complex with iodine as the commercially available topical antiseptic Betadine ( ). It also forms a remarkable variety of chemically specific complexes with drugs and hormones such as the tetracyclines, phenothiazine antipsychotics, the antiepileptic drug phenytoin, procaine local anesthetics, and methyldopa antiparkinsonian drugs ( ). In its insoluble, chemically cross-linked form, PNVP has also been used as a concentrating agent for a variety of phenols and catechol compounds (22). 

Veterinary drugs are used to treat animals for bacterial infections (antibiotics) and parasitic infestations (anthelmintics, coccidiostats), to enhance growth (antibiotics, anabohcs, partitioning agents, thyrostats), to control fertility and reproduction (steroid hormones), or to alter behavior (tranquillizers and sedatives). Within each of the drug types there are different classes and methods for residue analysis are typically class specific (e.g., methods for the class of tetracycline antibiotics). In certain cases, mrdtiresidue methods are available that are broader than specific classes. 

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