PHA Case Study III (Answers)

Transcription

1 PHA 5128 as Study III (Answrs) 1. TL is a 25 yar old mal who was admittd for a soft tissu infction in his abdomn. H is 5'10", 175 Ibs, WB 19, and BUN/Sr 12/1.1. Wound culturs ar positiv for Klbsilla pnumonia. You ar askd to rviw is mdication rcords and initiat gntamicin thrapy. omplt and initial workup and valuation (prospctiv sris) on this patint and counsl til patint on his antibiotic thrapy and writ and ordr for th pharmacy to fill. 1. Rcommnd a dsirabl rgimn for this patint 2. List thr important physical charactristics you should assss whn counsling th patint. 3. How would you writ (wording) th ordr to for this drug thrapy? Aftr two days, you rviw his chart and find that th lvls that you rqustd hav bn compltd and rportd as follows: gntamicin (pak) gntamicin (trough) 6.9 mcg/ml 0.9 mcg/ml Plas valuat (calculat) what his tru srum concntrations wr using ths rportd valus. Assum that th infusion was 30 uts, th pak was drawn 30 aftr th nd of th infusion, and that th trough was drawn 30 uts prior to th nxt dos (undr idal conditions) Would you rcommnd any changs in th rgimn basd on ths rcnt laboratory data? Dosing rgimn dsign: Ag25 yr; BW79.5 kg; Sr1.1 mg/dl; T30; pak (dsird)8 ug/ml, trough (dsird)1 ug/ml First, rl: IBW50+2.3*1073 kg (140 25) 73 L cr 106mL / 6.36L / h Thn V d and find k: V d 0.25*BW 0.25* L k L/V d 6.36/ h -1

2 Find Dosing Intrval and ndd dos: ln(8 /1) τ h 8h (1 ) D mg (1 ) So th dosing rgimn: 160 mg q8h Patint charactristics: 1) Edma 2) Wight 3) Rnal function 4) Ag 5) Othr mds (pnicillin) Lab data aftr 2 d thrapy: pak 6.9 mcg/ml, trough 0.9 mcg/ml Tru pak and trough : * mcg * kt* mcg * kt From th suggstd dosing rgimn, tru stady-stat pak and troughs should b (1 ) mcg (1 ) mcg / ml t 1/2 basd of 2 d data 2h, t 1/2 basd on rl 2.2 h littl diffrnc in prdictd and actual blood valus no nd to adjust

3 2. L.F., a 28-yar-old, 75 kg mal, is rciving 100 mg of tobramycin infusd IV ovr 30 ut priod q8h. His srum cratinin has incrasd from 1 mg/dl to 1.8 mg/dl ovr th past 24 hours. Sinc his rnal function appars to b dcrasing, thr plasma sampls wr obtaind to monitor srum gntamicin concntrations as follows: just bfor a dos; on hour aftr that sam dos; and ight hours aftr that dos (two troughs and on pak lvl). Th srum tobramycin concntrations at ths tims wr 4 mg/l, 8 mg/l, and 5 mg/l, rspctivly. alculat th volum of distribution, liation rat constant, and claranc of tobramycin for L.F. Also, using th pharmacokintic paramtrs calculatd for L.F. abov, dvlop a dosing rgimn that will produc rasonabl tru pak (10 mg/l) and trough (1 mg/l) concntrations of tobramycin. 8 ln 5 7 k 0.067h mg/l t1 / h ) ( ) V d L pr-dos lvl l k Vd L / h 25 ml/ Tru Pak 10 mg/l 10 ln τ h ) ) D mg 200mg q36h 0.033

4 3. A patint was givn 80 mg gntamicin ovr 30 uts (i.v.) from 9:30 to 10:00 am. Th following two srum lvls wr masurd: 6.5 µg/ml at 10:30 am and 1.2 µg/ml at 5:00 pm. alculat: a. th liation rat constant k k 6.5 ln h 6.5 b. th liation half-lif t1 / h 0.26 c. th pak concntration at 10:00 am µ g / ml d. th trough concntration at 5:30 pm g / ml µ. th volum of distribution (1 ) V d L (7.4.1 ) f. th claranc L L / h or 51 ml /

5 4. A patint is admittd with an acut drug ovrdos. A srum lvl is masurd at 45 µg/ml. Assug an 8 hour half-lif and no furthr drug absorption, how long dos it tak for th srum lvl to drop to th uppr limit of th thraputic rang (20 µg/ml)? k 0.087h t ln( 0.44) 0.087t t t t 9.3 h