Spectinomycin

Spectinomycin is a broad-spectrum antibiotic and inhibits the growth of a variety of gram-positive and gram-negative organisms. Spectinomycin acts by selectively targeting to the bacterial ribosome and interrupting protein synthesis. Spectinomycin is also a noncompetitive inhibitor of td intron RNA^{[1][2][3][4][5]}. IC50 & Target: bacterial ribosomal subunit^[5] In Vitro: Spectinomycin selectively inhibits protein synthesis in cells and in extracts of Escherichia coli.
Spectinomycin (50 μg/mL) inhibits Escherichia coli growth rapidly and reversibly, and suppresses amino acid incorporation immediately^[1].
Spectinomycin (1 μg/mL or 3 μM) inhibits polypeptide synthesis directed either by endogenous messenger RNA or by MS-2 bacteriophage RNA, with maximum inhibition of 70-80% in extracts of Escherichia coli^[1].
Spectinomycin blocks the translocation of peptidyl-tRNAs from A-site to P-site by inhibiting the binding of elongation factor G to the ribosome^[2].
Spectinomycin interacts specifically with the residues G1064 and 01192 in 16S rRNA and potentially makes it inactive^[2].
Spectinomycin exhibits splicing inhibition and dependent on pH changes and Mg²⁺ concentration, indicating electrostatic interactions with the intron RNA^[3].
In Vivo: Spectinomycin (20 mg/kg; i.m.; 20-100 mg/kg; 9 d) shows the safety in healthy chicks^[4].
Spectinomycin (10 mg/kg; i.v.; single dose) has the major elimination pathway by renal excretion, approximately 55% is excreted into the urine in unchanged form^[5].
Pharmacokinetics of Spectinomycin in Rat^[5]

Parameter	C0 (μg/mL)	AUC0-∞ (μg?h/mL)	Vd (L/kg)	CL (L/h/kg)	MRT (h)	T1/2α (h)	T1/2β (h)	T1/2γ (h)	fe	CLrenal (L/h/kg)	Eratio
Non atrioventricular analysis	44.3	16.8	0.756	0.602	0.757	/	/	/	0.553	0.359	1.00
Three-compartment model	37.8	15.7	0.747	0.649	1.11	/	0.237	0.754	19.5	/	/