Distal to the superior and extensor retinacula of the foot it becomes the dorsal artery of the foot. The posterior tibial forms a direct continuation of the popliteal artery which enters the flexor compartment of the lower leg to descend behind the medial malleolus where it divides into the medial and lateral plantar arteries, of which the posterior branch gives rise to the fibular artery.For practical reasons the lower limb is subdivided into somewhat arbitrary regions: The regions of the hip are all located in the thigh: anteriorly, the subinguinal region is bounded by the inguinal ligament, the sartorius, and the pectineus and forms part of the femoral triangle which extends distally to the adductor longus. Posteriorly, the gluteal region corresponds to the gluteus maximus. The anterior region of the thigh extends distally from the femoral triangle to the region of the knee and laterally to the tensor fasciae latae. The posterior region ends distally before the popliteal fossa. The anterior and posterior regions of the knee extend from the proximal regions down to the level of the tuberosity of the tibia. In the lower leg the anterior and posterior regions extend down to the malleoli. Behind the malleoli are the lateral and medial retromalleolar regions and behind these is the region of the heel. Finally, the foot is subdivided into a dorsal region superiorly and a plantar region inferiorly. Veins
The veins are subdivided into three systems. The deep veins return approximately 85 percent of the blood and the superficial veins approximately 15 percent.
These include medications such as methadone, amiodarone, citalopram, and fluconazole. Other medications may increase the risk for a low level of potassium in the blood, thereby indirectly increasing the risk for QT prolongation. For example, dexamethasone, hydrochlorothiazide, and theophylline can lower the level of potassium in the blood. CNS depression
Lofexidine can depress the central nervous system (CNS), which, in combination with other CNS depressants, may reduce a persons ability to perform tasks that require skills and attention. For example, clobazam, gabapentin, and levetiracetam all can depress the CNS. Hypotension
The risk of hypotension (low blood pressure) is increased when lofexidine is combined with other drugs that lower blood pressure. These may include losartan, metoprolol, and pramipexole. Pharmacology
Lofexidine is an agonist at the α-2A, 2B, and 2C adrenergic receptor subtypes, with the highest activity at the alpha-2A receptor. Ki represents the dissociation constant for lofexidines binding to a specific subtype of alpha-2 receptor. The smaller the Ki value, the stronger the drug binds to the receptor to exert its activity. Lofexidine inhibits the release of norepinephrine in the central and peripheral nervous system, thereby reducing some of the symptoms of opioid withdrawal, but it has no documented effect on drug craving and endogenous opioid levels. Pharmacokinetics
Lofexidines oral bioavailability is about 90%, with extensive oral absorption. Peak plasma concentrations occur at 3 hours after a single administration, with a half-life of 11 hours. Lofexidine is extensively metabolized by the liver, and primarily cleared by the kidney. It is 80-90% plasma protein bound.