cially in the elderly, who are more susceptible to the anticholinergic effects. Consider alternatives to these other medications, if available. Clinicians should note that antimuscarinic effects might be seen not only on bladder smooth muscle, but also on GI function, the eye, and temperature regulation. Blurred vision, constipation, and dry mouth may be more prominent additive effects. With many of the listed agents, additive drowsiness may also occur when combined with trospium.
Umeclidinium: There is the potential for umeclidinium to have additive anticholinergic effects when administered with other anticholinergics or antimuscarinics. Per the manufaturer, avoid concomitant administration of umeclidinium with other anticholinergic medications when possible.
Umeclidinium; Vilanterol: There is the potential for umeclidinium to have additive anticholinergic effects when administered with other anticholinergics or antimuscarinics. Per the manufaturer, avoid concomitant administration of umeclidinium with other anticholinergic medications when possible.
Zonisamide: Zonisamide use is associated with case reports of decreased sweating, hyperthermia, heat intolerance, or heat stroke and should be used with caution in combination with other drugs that may also predispose patients to heat-related disorders like anticholinergics.
PREGNANCY AND LACTATION
Pregnancy
Atropine is classified as FDA pregnancy risk category C. There are no adequate and well-controlled studies in pregnant women. Although observational data of mothers exposed to atropine during pregnancy suggest the possibility of defects, a definitive association of the drug with fetal harm has not been established. Therefore, in making the decision to administer this drug during pregnancy, the potential risks to the fetus must be weighed against the potential benefits to the mother. The drug is commonly used during labor prior to cesarean section, to reduce secretions.
Trace amounts of atropine are excreted in human breast milk. The American Academy of Pediatrics has considered use of atropine compatible with breast-feeding, due to the lack of reported effects on the nursing infant. Of note, long-term use of antimuscarinic medications has been reported to inhibit lactation; thus, some experts discourage the use of these agents during breast-feeding. The manufacturer advises caution when administering to lactating women because infants may be particularly sensitive to the anticholinergic effects of the drug. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.
MECHANISM OF ACTION
Atropine is a competitive inhibitor at autonomic postganglionic cholinergic receptors. These include receptors found in GI and pulmonary smooth muscle, exocrine glands, the heart, and the eye. Atropine does not block the actions of acetylcholine at the neuromuscular junction. Activity is due primarily to l-hyoscyamine, which possesses all of the antimuscarinic activity, and not d-hyoscyamine, which essentially has no peripheral antimuscarinic activity. The degree of sensitivity of various muscarinic receptors to antimuscarinic agents is dose-dependent. The most sensitive receptors are those of the saliva |
