Role in disease
Deficiency of this protein is associated with hereditary angioedema ("hereditary angioneurotic edema"), or swelling due to leakage of fluid from blood vessels into connective tissue. Deficiency of C1-inhibitor permits plasma kallikrein activation, which leads to the production of the vasoactive peptide bradykinin. Also, C4 and C2 cleavage goes unchecked, resulting in auto-activation of the complement system. In its most common form, it presents as marked swelling of the face, mouth and/or airway that occurs spontaneously or to minimal triggers (such as mild trauma), but such swelling can occur in any part of the body. In 85% of the cases, the levels of C1-inhibitor are low, while in 15% the protein circulates in normal amounts but it is dysfunctional. In addition to the episodes of facial swelling and/or abdominal pain, it also predisposes to autoimmune diseases, most markedly lupus erythematosus, due to its consumptive effect on complement factors 3 and 4. Mutations in the gene that codes for C1-inhibitor, SERPING1, may also play a role in the development of age-related macular degeneration. At least 97 disease-causing mutations in this gene have been discovered.Despite uncontrolled auto-activation, it is important to note that levels of key complement components are low during an acute attack because they are being consumed - indeed, low levels of C4 are a key diagnostic test for hereditary angioedema. This situation is analogous to the low levels of clotting factors found in disseminated intravascular coagulation (DIC).
Tolterodine, sold under the brand name Detrol among others, is a medication used to treat frequent urination, urinary incontinence, or urinary urgency. Effects are seen within an hour. It is taken by mouth.Common side effects include headache, dry mouth, constipation, and dizziness. Serious side effects may include angioedema, urinary retention, and QT prolongation. Use in pregnancy and breastfeeding are of unclear safety. It works by blocking muscarinic receptors in the bladder thus decreasing bladder contractions.Tolterodine was approved for medical use in 1998. It is available as a generic medication. In 2019, it was the 292nd most commonly prescribed medication in the United States, with more than 1 million prescriptions. Medical uses
Detrusor overactivity (DO, contraction of the muscular bladder wall) is the most common form of urinary incontinence (UI) in older adults. It is characterized by uninhibited bladder contractions causing an uncontrollable urge to void. Urinary frequency, urge incontinence and nocturnal incontinence occur. Abnormal bladder contractions that coincide with the urge to void can be measured by urodynamic studies. Treatment is bladder retraining, pelvic floor therapy or with drugs that inhibit bladder contractions such as oxybutynin and tolterodine. Side effects
Known side effects:

Dry mouth
Decreased gastric motility (upset stomach)
Headache
Constipation
Dry eyes
Sleepiness
Urinary retentionThe following reactions have been reported in people who have taken tolterodine since it has become available:

Allergic reactions including swelling
Rapid heartbeat or abnormal heartbeat
Accumulation of fluid in the arms and legs
HallucinationsTolterodine is not recommended for use in people with myasthenia gravis and angle closure glaucoma.