Adverse effects
Side effects include dry mouth and throat, increased appetite leading to weight gain, eye pain, blurred vision, restlessness, dizziness, arrhythmia, flushing, and faintness. An overdose will cause headache, nausea, vomiting, and central nervous system symptoms including disorientation, hallucinations, euphoria, sexual arousal, short-term memory loss, and possible coma in extreme cases. The euphoric and sexual effects are stronger than those of atropine but weaker than those of Hyoscine, as well as dicycloverine, orphenadrine, cyclobenzaprine, trihexyphenidyl, and ethanolamine antihistamines like phenyltoloxamine. Pharmacology
Hyoscyamine is an antimuscarinic; i.e., an antagonist of muscarinic acetylcholine receptors. It blocks the action of acetylcholine at parasympathetic sites in sweat glands, salivary glands, stomach secretions, heart muscle, sinoatrial node, smooth muscle in the gastrointestinal tract, and the central nervous system. It increases cardiac output and heart rate, lowers blood pressure and dries secretions. It may antagonize serotonin. At comparable doses, hyoscyamine has 98 per cent of the anticholinergic power of atropine. The other major belladonna-derived drug hyoscine (known in the United States as Scopolamine) has 92 per cent of the antimuscarinic potency of atropine. Biosynthesis in plants
Hyoscyamine can be extracted from plants of the family Solanaceae, notably Datura stramonium. As hyoscyamine is a direct precursor in the plant biosynthesis of hyoscine, it is produced via the same metabolic pathway.The biosynthesis of hyoscine begins with the decarboxylation of L-ornithine to putrescine by ornithine decarboxylase (EC 4.1.1.17).
Later stages are characterized by dense collagenous tissue in the joint capsule.Under the microscope, the appearance of the affected shoulder joint capsule tissue is similar to the appearance of the tissue that restricts finger movement in Dupuytrens contracture. Diagnosis
Adhesive capsulitis can be diagnosed by history and physical exam. It is often a diagnosis of exclusion, as other causes of shoulder pain and stiffness must first be ruled out. On physical exam, adhesive capsulitis can be diagnosed if limits of the active range of motion are the same or similar to the limits to the passive range of motion. The movement that is most severely inhibited is external rotation of the shoulder.Imaging studies are not required for diagnosis, but may be used to rule out other causes of pain. Radiographs will often be normal, but imaging features of adhesive capsulitis can be seen on ultrasound or non-contrast MRI. Ultrasound and MRI can help in diagnosis by assessing the coracohumeral ligament, with a width of greater than 3 mm being  60% sensitive and 95% specific for the diagnosis. Shoulders with adhesive capsulitis also characteristically fibrose and thicken at the axillary pouch and "rotator interval", best seen as a dark signal on T1 sequences with edema and inflammation on T2 sequences. A finding on ultrasound associated with adhesive capsulitis is hypoechoic material surrounding the long head of the biceps tendon at the rotator interval, reflecting fibrosis.