Trough level

Nicotine Delivery Systems. For all transdermal nicotine products, the hypothesis is that continuous deflvery of nicotine [34-11-3] ne t trough levels during smoking should alleviate physical nicotine withdrawal symptoms and allow the smoker to concentrate on eliminating the behavioral aspects of addiction. 

Established standard dosage produces the target concentration (Ctarget) between normal peak and trough levels. 

The Dettli rule might result in underdosage because of too infrequent peak levels the Kunin rule might result in overdosage because of toxic trough levels. The third, the target concentration approach was proposed by Nikolas Holford. 

Methadone is a p receptor agonist with special properties that make it particularly useful as a maintenance agent. Rehably absorbed orally, it does not reach peak concentration until about 4 hours after administration and maintains a large extravascular reservoir (Kreek 1979). These properties minimize acute euphoric effects. The reservoir results in a plasma half-life of 1—2 days, so there are usually no rapid blood level drops that could lead to withdrawal syndromes between daily doses. Effective blood levels are in the range of 200-500 ng/mL. Trough levels of 400 ng/mL are considered optimal (Payte and Khouri 1993). There is wide variability among individuals in blood levels with identical doses (Kreek 1979), and some have inadequate levels even with doses as high as 200 mg/day (Tennant 1987 Tenore 2003). 

Target trough levels between 15 and 20 mcg/mL (to increase pulmonary penetration)... 

Monitor theophylline levels with goal serum concentrations in the range of 5 to 15 mcg/mL (28 to 83 4mol/L). Trough levels should be obtained 1 to 2 weeks after initiation of treatment... 

Obtain serum drug levels for aminoglycosides and/or vancomycin and perform pharmacokinetic analysis. Adjust the dose, if needed, according to the parameters in Table 13-2. Obtain follow-up trough levels at weekly intervals or sooner if renal function is unstable. Follow serum creatinine levels if renal function is unstable. Hearing tests may be scheduled yearly or per patient preference. 

Continue to monitor AED serum trough concentrations approximately every 3 to 5 days until the AEDs have reached steady-state concentrations. Give additional loading doses or hold doses as needed to maintain trough concentrations in the patient s therapeutic range. Be sure to evaluate the time the sample was drawn to assure it is a trough level. 

O Intravenous factor replacement with recombinant or plasma-derived products to treat or prevent bleeding is the primary treatment hemophilia. Primary prophylaxis is defined as the regular administration of factor concentrates with the intention of preventing joint bleeds.4 The rationale for primary prophylaxis is that individuals with factor levels of greater than 0.02 unit/mL (2 IU/dL) rarely suffer from spontaneous bleeds and arthropathy. Therefore, to maintain a trough level above this might convert severe hemophilia to moderate disease, with the abolition of joint bleeds and the associated arthropathy.5... 

Everolimus, a derivative of sirolimus, is a novel macrocyclic immunosuppressant. Risk of acute rejection increases when the everolimus trough level falls below 3 fig/L in renal transplant patients.46... 

Eideriy Clearance of ticlopidine is somewhat lower in elderly patients and trough levels are increased. No overall differences in safety or efficacy were observed between elderly patients and younger patients, but greater sensitivity of some older individuals cannot be ruled out. 

Monitoring Perform auditory function serial tests and monitor serum levels. When monitoring vancomycin serum levels, draw a peak concentration 1.5 to 2.5 hours after the completion of a 1-hour infusion and a trough concentration within 1 hour of the next scheduled dose. Peak levels are generally expected to be in the 30 to 40 mg/mL range and trough levels in the 10 to 15 mg/mL range. 

When catheter-related septicemia is suspected or proven vancomycin ((2-3) x I g) is started while vancomycin trough levels are monitored. Removal of the catheter must be considered with persistent fever or when blood cultures remain positive under effective vancomycin trough levels (10-15 mg/1). In a rapidly progressive infection (pneumonia) in a neutropenic patient anti-pseudomonas duo-therapy, e.g. ceftazidime with tobramycin, should be considered. 

Serum peak, drawn 30-60 min after iV iNForbO min after IM inj trough level drawn just before next dose adjust dosage per levels (usual therapeutic plasma levels peak 20-35 mg/L, trough 10 mg/Lor less)... 

Blood level monitoring maintenance of 24-hr trough levels of 250-800 ng/ml (whole blood, RIA) or 50-300 ng/ml (plasma, RIA) should minimize side effects and rejection events... 

Vancomycin therapeutic peak serum level is 20-40 mcg/ml, and the trough level is 5-15 mcg/ml. The toxic peak serum level is greater than 40 mcg/ml, and the trough level is greater than 15 mcg/ml... 

A 17-year-old boy with bipolar disorder is started on lithium therapy at 600 mg bid. The initial lithium concentration is 0.8 mmol/L. As the patient s pressured speech and labile mood do not improve with time, the psychiatrist in charge wonders whether the lack of efficacy is due to insufficient coverage or to noncompliance. A repeat trough level is 0.3 mmol/L (Fig. 4.4A). 

In this example, simulation of the lithium serum concentration profile based on population PK data reveals that this patient has a higher than normal clearance. Furthermore, the first level was not a trough level. The model-based profile and subsequent Bayesian individualization process are shown in Figure 4.4B. 

The investigators measured messenger ribonucleic acid (mRNA) expression levels of MDRl and CYP3A4 in mucosal cells of the upper jejunum collected during living-donor liver transplantation in 48 recipients. Tacrolimus was initiated at an oral dose of 0.075 mg/kg every 12 hours and adjusted on the basis of trough levels in whole blood. 

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