3.14
구획 모델: 2구획 모델
2구획 모델은 신체를 중앙 구획과 말초 구획으로 나누어 장기와 조직 간의 다양한 혈액 관류 속도를 고려하여 약물 분포에 영향을 줍니다. 중앙 구획에는 약물 분포가 빠른 혈액과 고도로 관류된 조직이 포함되어 있고, 주변 구획에는 약물 분포가 느린 조직이 포함되어 있습니다…
2구획 모델은 혈액 관류 속도가 장기와 조직에 따라 다르기 때문에 약물이 몸 전체에 균일하게 분포되어 있지 않다고 가정합니다. 따라서 이 모델은 신체를 중앙 구획과 주변 구획으로 나눕니다.
중앙 구획은 혈액과 약물이 빠르게 분포되는 고도로 관류된 조직으로 구성됩니다.
말초 구획은 약물 분포가 느린 조직으로 구성됩니다.
IV 볼루스를 1회 투여한 후 약물 농도는 혈장에서 높고 조직에서는 낮습니다.
구획 사이의 약물 분포는 전달 상수 또는 마이크로 상수라고 하는 속도 상수에 의해 정의되는 1차 프로세스입니다.
분포로 인해 혈장에서 약물 농도가 급격히 감소하고 평형에 도달할 때까지 조직에서 증가합니다.
그 후, 약물 농도는 제거로 인해 두 구획 모두에서 천천히 감소합니다.
요컨대, 혈장 약물 농도는 이중으로 기하급수적으로 감소하며, 여기서 급격한 초기 감소는 분포 또는 ɑ 단계이고 후속 감소는 제거 또는 β 단계입니다.
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Q1: Why does the two-compartment model divide the body into central and peripheral compartments?
The two-compartment model accounts for varying blood perfusion rates among organs and tissues. The central compartment includes blood and highly perfused tissues where drugs distribute rapidly, while the peripheral compartment contains tissues with slower drug distribution. This division reflects the reality that drug distribution is not uniform throughout the body.
Q2: What happens to drug concentration immediately after an IV bolus dose?
Following a single IV bolus dose, drug concentration is initially high in plasma and low in tissues. The drug concentration rapidly declines in plasma while simultaneously increasing in tissues as distribution occurs. This rapid initial decline represents the distribution or alpha phase of plasma concentration change.
Q3: How does drug distribution between compartments follow first-order kinetics?
Drug distribution between the central and peripheral compartments is a first-order process defined by rate constants termed transfer constants or micro constants. These constants govern how quickly drug molecules move from highly perfused tissues to slower-perfused tissues, controlling the rate and extent of drug redistribution throughout the body.
Q4: What occurs when drug concentration reaches equilibrium between compartments?
Once equilibrium is reached between central and peripheral compartments, drug concentration stops changing due to distribution. After this point, both compartments experience a slow, simultaneous decline in drug concentration due to elimination processes. This slower phase is called the elimination or beta phase.
Q5: Why does plasma drug concentration decline bi-exponentially in the two-compartment model?
Plasma drug concentration declines bi-exponentially because two distinct processes occur sequentially. The rapid initial decline represents the distribution or alpha phase as drug moves from plasma to tissues. The subsequent slower decline represents the elimination or beta phase after equilibrium is established and drug is removed from both compartments.
Q6: How does the two-compartment model differ from assuming uniform drug distribution?
The two-compartment model recognizes that blood perfusion rates vary among different organs and tissues, preventing uniform drug distribution. By dividing the body into central and peripheral compartments with different distribution rates, the model accurately predicts how drug concentration changes over time in plasma and tissues, rather than assuming instantaneous equilibrium.
Q7: What is the relationship between transfer constants and drug movement in compartmental analysis?
Transfer constants, also called micro constants, quantify the rate of drug movement between central and peripheral compartments during the first-order distribution process. These constants determine how quickly drug redistributes from highly perfused tissues to slower-perfused tissues and influence the duration and shape of the distribution phase in plasma concentration profiles.