A simple HPLC-fluorescence method for the measurement of R,S-sotalol in the plasma of patients with life-threatening cardiac arrhythmias.
R,S-sotalol, a ss-blocker drug with class III antiarrhythmic properties, is prescribed to patients with ventricular, atrial and supraventricular arrhythmias. A simple and sensitive method based on HPLC-fluorescence is described for the quantification of R,S-sotalol racemate in 500 microl of plasma. R,S-sotalol and its internal standard (atenolol) were eluted after 5.9 and 8.5 min, respectively, from a 4-micron C18 reverse-phase column using a mobile phase consisting of 80 mM KH2PO4, pH 4.6, and acetonitrile (95:5, v/v) at a flow rate of 0.5 ml/min with detection at lambdaex = 235 nm and lambdaem = 310 nm, respectively. This method, validated on the basis of R,S-sotalol measurements in spiked blank plasma, presented 20 ng/ml sensitivity, 20-10,000 ng/ml linearity, and 2.9 and 4.8% intra- and interassay precision, respectively. Plasma sotalol concentrations were determined by applying this method to investigate five high-risk patients with atrial fibrillation admitted to the Emergency Service of the Medical School Hospital, who received sotalol, 160 mg po, as loading dose. Blood samples were collected from a peripheral vein at zero, 0.5, 1.0, 1.5, 2.0, 3.0, 4. 0, 6.0, 8.0, 12.0 and 24.0 h after drug administration. A two-compartment open model was applied. Data obtained, expressed as mean, were: C MAX = 1230 ng/ml, T MAX = 1.8 h, AUC T = 10645 ng h-1 ml-1, Kab = 1.23 h-1, alpha = 0.95 h-1, ss = 0.09 h-1, t((1/2))ss = 7.8 h, ClT/F = 3.94 ml min-1 kg-1, and Vd/F = 2.53 l/kg. A good systemic availability and a fast absorption were obtained. Drug distribution was reduced to the same extent in terms of total body clearance when patients and healthy volunteers were compared, and consequently elimination half-life remained unchanged. Thus, the method described in the present study is useful for therapeutic drug monitoring purposes, pharmacokinetic investigation and pharmacokinetic-pharmacodynamic sotalol studies in patients with tachyarrhythmias.
Santos
S R
SR
Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina and Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, SP, Brasil.
Papini
O
O
Omosako
C E
CE
Pereira
M D
MD
Quintavalle
T B
TB
Riccio
M F
MF
Kurata
A
A
Pereira
V A
VA
Di-Pietro
G
G
Della-Paschoa
O E
OE
Danhof
M
M
Da-Luz
P L
PL
D000889:Anti-Arrhythmia Agents / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use; D019540:Area Under Curve; D001281:Atrial Fibrillation / Q000097:blood* / Q000188:drug therapy; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013015:Sotalol / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use
D000889:Anti-Arrhythmia Agents; D013015:Sotalol