Maintenance dose rate

Clearance will determine the maintenance dosing rate to maintain an average plasma concentration. 

The half-life (i.e. both volume of distribution and clearance) will guide how the maintenance dosing rate should be divided in time to keep fluctuations in plasma concentration within acceptable limits. 

Drugs that are completely or largely metabolised to inactive products give normal doses. When the special note of caution (above) applies, a modest reduction of initial dose and the maintenance dose rate are justified while drug effects are assessed. 

Diet should be modified only in cases where foods have been proven to elicit symptoms. Patients with mastocytosis and Hymenoptera venom exposure are at risk for severe anaphylaxis. Thus, specific immunotherapy should be considered in patients with Hymenoptera venom allergy and then administered under close supervision [31]. The majority of patients with mastocytosis reportedly tolerate immunotherapy without significant side effects and appear protected following this approach [33,40]. However, there does appear to be some increased risk for adverse reactions during initiation of immunotherapy, as well as for therapy failures [31, 33]. An increased maintenance dose of insect venom has been reported to carry better success rates by sting provocation [41]. Also, in the light of 2 fatal cases of anaphylaxis after discontinuation of SIT in patients with mastocytosis [30], lifelong immunotherapy should be considered [26]. 

Although an initial dose of 160 to 325 mg is required to achieve rapid platelet inhibition, long-term therapy with doses of 75 to 150 mg daily are as effective as higher doses. In addition, doses of less than 325 mg daily are associated with a lower rate of bleeding.29,30 The major bleeding rate associated with chronic aspirin administration in doses less than 100 mg per day is 1.6%, whereas the rate with doses more than 100 mg per day is 2.3%.30 Therefore, a daily maintenance dose of 75 to 160 mg is recommended.2... 

Because it is a small protein, the factor IX molecule passes into the intravascular and the extravascular spaces. Therefore, the volume of distribution of recombinant factor IX is twice that of factor VIII. Consequently, 1 unit of factor IX administered per kilogram of body weight yields a 1% rise in the plasma factor IX level (0.01 unit/mL, or 1 IU/dL). Thus 1750 units of factor IX provides an incremental increase of 50% of normal (0.5 unit/mL, or 50 IU/dL), that is, 1750 units/70 kg x 0.01 unit/mL (1 IU/dL).12 Additionally, the recovery rate with recombinant factor IX is 20% lower than that with the plasma-derived products. Therefore, initial and subsequent maintenance doses should be adjusted accordingly. 

Loading Dose (Maximum Dose) Rate of Infusion Maintenance Dose ... 

Stabilize the patient s asthma before treatment is started. Initially, use aerosol concurrently with usual maintenance dose of systemic steroid. After approximately 1 week, start gradual withdrawal of the systemic steroid by reducing the daily or alternate daily dose. Make the next reduction after 1 to 2 weeks, depending on response. Generally, these decrements should not exceed 25% of the prednisone dose or its equivalent. A slow rate of withdrawal cannot be overemphasized. 

Renal function Impairment- Ceftazidime is excreted by the kidneys, almost exclusively by glomerular filtration. In patients with impaired renal function (glomerular filtration rate (GFR) less than 50 mL/min), reduce dosage to compensate for slower excretion. In patients with suspected renal insufficiency, give an initial loading dose of 1 g. Estimate GFR to determine the appropriate maintenance dose. 

IV Following induction, the recommended maintenance dose is 5 mg/kg given as a constant rate IV infusion over 1 hour once per day 7 days per week, or 6 mg/kg once per day 5 days/week. 

Acutehypotensionunresponsivetofluidvolumereplacement IV Initially,administerat 0.5-1 mcg/min. Adjust rate of flow to establish and maintain desired BP (40 mm Hgbe-low preexisting systolic pressure). Average maintenance dose 8-30 mcg/min. 

Mild to moderate hypotension SC,1M 2-5mg(range 1-10 mg), repeated no more than every 10-15 minutes. Maximum initial dose 5 mg. IV 0.2 mg (range 0.1 to 0.5 mg), given no more frequently than every 10-15 minutes. Maximum initial dose 0.5 mg. Severe hypotension, severe shoch IV Initially, 100-180 mcg/minlVinfusion,withdose titration to the desired MAP and SVR. A maintenance infusion rate of 40-60 mcg/min IV is usually adequate after blood pressure stabilizes. If necessary to produce the desired pressor response, additional phenylephrine in increments of 10 mg or more may be added to the infusion solution and the rate of flow adjusted according to the response of the patient. 

In patients with heart failure, lidocaine s volume of distribution and total body clearance may both be decreased. Thus, both loading and maintenance doses should be decreased. Since these effects counterbalance each other, the half-life may not be increased as much as predicted from clearance changes alone. In patients with liver disease, plasma clearance is markedly reduced and the volume of distribution is often increased the elimination half-life in such cases may be increased threefold or more. In liver disease, the maintenance dose should be decreased, but usual loading doses can be given. Elimination half-life determines the time to steady state. Thus, although steady-state concentrations may be achieved in 8-10 hours in normal patients and patients with heart failure, 24-36 hours may be required in those with liver disease. Drugs that decrease liver blood flow (eg, propranolol, cimetidine) reduce lidocaine clearance and so increase the risk of toxicity unless infusion rates are decreased. With infusions lasting more than 24 hours, clearance falls and plasma concentrations rise. Renal disease has no major effect on lidocaine disposition. 

In the majority of clinical situations, drugs are administered as a series of repeated doses or as a continuous infusion in order to maintain a steady-state concentration. Therefore, a maintenance dose must be calculated such that the rate of input is equal to the rate of drug loss. This may be determined using the following formula ... 

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