ThePharmaFacts

     TETRACYCLINE All are obtained from Actinomycetes species  T hey are bitter solids & their hydrochlorides soluble in water Derivatives of Octahedro Napthacene (having 4 annulated six- membered rings together) Amphoteric compounds (having both acid & base properties)   General Information:      General Structure:      SAR of Tetracyclines:       1.Modification at C1 & C3:         -  Keto-enol tautomerism of ring A in C1  &  C3 is common feature to all biologically active tetracyclines, blocking this system by forming derivatives  like A–C = O  at C1 and C3 results in loss of antibacterial activity          - Function of C1 & C3 is essential for activity       2. Modification at C2 position:          - Antibacterial activity depends on the carboxamide (CONH 2 ) moiety.          - Amide is best when left unsubstituted or monosubstitution is acceptable of 'alkylamino methyl amide/Mannich base' ( Rolitetracycline )         - Large alkyl group on the carboxa

Cephalosporins Derived from a fungus Acremonium which word is previously known as Cephalosporium Discovered in 1945 by Brotzu He observed that the culture produced substances which were effective against Salmonella typhi (an agent causing typhoid) General Information:     General Structure:                SAR Of Cephalosporins:      1.  7-Acylamino substituents: -      Acylation of the amino group generally increases potency against gram  positive bacteria, but decrease in gram-negative potency. -     High antibacterial activity is observed only when the new acyl groups are derived from carboxylic acids for gram-positive bacteria. -    Substituents on the aromatic ring that increases lipophilicity provide higher gram-positive activity and generally lower gram-negative activity. -    Phenyl ring in the side-chain can be replaced with other heterocycles with an improved spectrum of activity and pharmacokinetic properties and these include thiophene, tetrazole, furan, p