Minimal effective concentration

A measure of the actual amount of drug in the body can be obtained from the area under the curve of the temporal concentration curve (calculated by integration). Interestingly, the temporal behavior of a drug can be extremely important in therapeutics. For example, consider three preparations of a drug that present identical values for area under the curve (i.e., amount of drug absorbed) but have different kinetics of absorption (Figure 8.23). As shown, preparation B produces a useful profile whereby the concentration exceeds the minimal effective concentration... 

Infiltration (i.e., the injection of local anesthetics under the skin) of the surgical site provides adequate anesthesia if contiguous structures are not stimulated. Since the onset of local anesthesia is rapid, the surgical procedures can proceed with little delay. Minimally effective concentrations should be used, especially in extensive procedures, to avoid toxicity from overdosage. 

This illustration shows how biomarker-based risk posed by methylmercury (5.8 pg/L as a blood equivalent of the RfD and 58 pg/L as a minimal effect concentration in human fish-eating populations, according to benchmark dose analysis) can be used directly to interpret population biomonitoring data. Pathway analyses conducted by others (Stern et al. 2001 Carrington... 

C Valproic acid can be given IV while the patient is NPO and then she can be converted back to her oral regimen as soon as possible. Valproic acid has no interactions with propoxyphene or doxycycline. Valproic acid troughs (not peak levels) should be monitored to ensure minimal effective concentrations. 

When a plasma-concentration curve is constructed for different patients that have been given an identical dose of an identical drug, interindividual differences will be noted. In some cases, plasma concentrations in one patient may remain below the minimal effective concentration, whereas the plasma concentration in another patient reaches the minimum toxic concentration. Besides some very obvious causes, such as body weight and body composition, some other factors involved in the interindividual variability in pharmacokinetics are concisely described below. 

Intemasal delivery of peptide and protein drugs is severely restricted by pre-systemic elimination due to enz5miatic degradation or mucociliary clearance and by the limited extent of mucosal membrane permeability. a-CyD has been shown to remove some fatty acids from nasal mucosa and to enhance the nasal absorption of leuprolide acetate in rats and dogs. The utility of chemically modified CyDs as absorption enhancers for peptide drugs in rats has been demonstrated. For example, DM-P-CyD was shown to be a potent enhancer of insulin absorption in rats, and a minimal effective concentration of DM-(3-CyD for absorption enhancement exerted only a mild effect on the in vitro ciliary movement.The scope of interaction of insulin with CyDs is limited, because CyDs can only partially include the hydrophobic amino acid residues in peptides with small stability constants. Under in vivo conditions, these complexes will readily dissociate into separate components, and hence the displacement by membrane lipids may further destabilize the complexes. The direct interaction of peptides with CyDs is therefore of minor importance in the enhancement of nasal absorption. Of the hydrophilic CyDs tested, DM- 3-CyD had the most prominent inhibitory effect on the enzymatic degradation of both BLA and insulin in rat nasal tissue homogenates. Because of the limited interaction between peptides and CyDs,... 

Lag time = time from administration to appearance in blood. Onset of activity = time from administration to blood level reaching minimal effective concentration (MEC). Duration of action = time plasma concentration remains greater than MEC. 

Answer C. The fact that the drug has therapeutic efficacy for 6 h has no direct relationship to its half-life—it simply means that the drug is above its minimal effective concentration for 6 h. Doubling the dose (to 1 g) means that the drug level will be above the minimum for a longer period. Because the elimination half-life is 8 h, 500 mg of the drug will remain in the body 8 h after a dose of 1 g. Thus the total duration of effectiveness must be 8 + 6 = 14 h... 

Camite, CA, BBC. Used by French in solution in chloropicrin, also used by USA. Very effective war gas great persistence and lachrymatory power. Yellowish-white crystals, turn pink as they decompose. Technical product oily brown liquid, bp 242°C vapour pressure at 20°C 0.012 mmHg. Difficult to break down attacks metals but not glass. Very irritant minimal effective concentration 0.2 mg/m3 insupportable from 5 mg/m3. Said to be the most powerful lachrymator used in WWI about as potent as chloroacetophenone. Last lachrymator introduced in WWI 1918. Very persistent in soil. 

The nurse must also know the dmg s onset of action, peak action, and duration of action. As you ll recall from the previous chapter, onset is the time period when the dmg reaches the minimally effective concentration in the plasma. The peak action is when the dmg reaches the maximum concentration in the plasma. The duration is the length of time the therapeutic action will last. 

Calcium elenolate (LXVI) whose structure has just been revised from an open chain aliphatic dialdehyde is also a wide spectrum extracellular virus inactivator, as might possibly be expected from comparison of its structure with that of Kethoxal. The acid is obtained from extracts of olive plants and its calcium salt has a minimal effective concentration of 0-75 per cent when tested intranasally in hamsters infected with parainfluenza 3. This concentration applied six times in 28 hours had no toxic effects and aborted the virus infection. A concentration of 0-6 per cent tested intranasally in rabbits over an extended period produced mild to moderate changes in the nasal epithelium, but a 1 0 per cent nasal spray four times daily for 14 days was well tolerated in humans [245-247]. 

PGEj is a powerful inhibitor of platelet-to-glass adhesiveness in a whole-blood system and of in vitro platelet aggregation, induced by A.D.P., noradrenaline, A.T.P., 5-H.T., thrombin and collagen. Species where aggregation inhibition has been observed include the rat, pig and man [332-337] the minimal effective concentration for activity against ADP-induced aggregation of human platelets is 0 05 pg/ml [336]. 

The therapeutic window of an active substance is the blood concentration range within which the desired therapeutic effect will occur without serious side effects. The lower limit of the therapeutic window is the so-called minimal effective concentration (MEC). This is the lowest blood concentration of the active substance that exerts a therapeutic effect. The upper limit of the therapeutic window is the maximal tolerable concentration (MTC). When the MTC is reached or exceeded, unacceptable adverse effects of the active substance are likely to occur. 

Similarly, lithium-7 MRS has been used to examine the pharmacokinetics of lithium, a drug that is widely used in the treatment of a number of psychiatric disorders. Initial studies showed that there was a slow accumulation of lithium in the brain, which may be responsible for the delay in therapeutic response that is often seen following the initiation of therapy. Subsequent studies showed that lithium levels in the brain and muscle were lower than the average serum concentration. From the ratio of these in vivo measurements, the authors hypothesized that the minimal effective concentration of brain lithium level for maintenance treatment... 

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