But estradiol levels were not significantly different in the group that received both anastrozole and tamoxifen compared to the anastrozole alone group, so the decrease in anastrozole levels is not thought to be clinically important. Pharmacology
Pharmacodynamics
Anastrozole works by reversibly binding to the aromatase enzyme, and through competitive inhibition blocks the conversion of androgens to estrogens in peripheral (extragonadal) tissues. The medication has been found to achieve 96.7% to 97.3% inhibition of aromatase at a dosage of 1 mg/day and 98.1% inhibition of aromatase at a dosage of 10 mg/day in humans. As such, 1 mg/day is considered to be the minimal dosage required to achieve maximal suppression of aromatase with anastrozole. This decrease in aromatase activity results in an at least 85% decrease in estradiol levels in postmenopausal women. Levels of corticosteroids and other adrenal steroids are unaffected by anastrozole. Pharmacokinetics
The bioavailability of anastrozole in humans is unknown, but it was found to be well-absorbed in animals. Absorption of anastrozole is linear over a dosage range of 1 to 20 mg/day in humans and does not change with repeated administration. Food does not significantly influence the extent of absorption of anastrozole. Peak levels of anastrozole occur a median 3 hours after administration, but with a wide range of 2 to 12 hours. Steady-state levels of anastrozole are achieved within 7 to 10 days of continuous administration, with 3.5-fold accumulation.
Periorbital sensory loss and impaired corneal reflex may be noted. Papilledema, retinal hemorrhages, and decreased visual acuity and blindness may occur from venous congestion within the retina. Fever, tachycardia and sepsis may be present. Headache with nuchal rigidity (neck stiffness) may occur. One or both pupils may be dilated and sluggishly reactive. Infection can spread to contralateral cavernous sinus within 24–48 hours of initial presentation. Cause
Septic CST most commonly results from contiguous spread of infection from a nasal furuncle (50%), sphenoidal or ethmoidal sinuses (30%) and dental infections (10%). Less common primary sites of infection include tonsils, soft palate, middle ear, or orbit (orbital cellulitis). The highly anastomotic venous system of the paranasal sinuses allows retrograde spread of infection to the cavernous sinus via the superior and inferior ophthalmic veins. It was previously thought that veins in the area were valveless and that this was the major cause of the retrograde spread, but studies have since shown that the ophthalmic and facial veins are not valveless.Staphylococcus aureus is the most common infectious microbe, found in 70% of the cases. Streptococcus is the second leading cause. Gram-negative rods and anaerobes may also lead to cavernous sinus thrombosis. Rarely, Aspergillus fumigatus and mucormycosis cause CST.Aseptic cavernous sinus thrombosis is much less common and is usually associated with other disorders including trauma, circulatory problems, nasopharynx cancers and other tumors of the skull base, dehydration, and anemia. Diagnosis
The diagnosis of cavernous sinus thrombosis is made clinically, with imaging studies to confirm the clinical impression.