Can any of the patient's medications, including Metoprolol Succinate (Extended Release 24 Hour) (metoprolol), Melatonin, Lurasidone HCl, Bupropion (bupropion) HCl, Atorvastatin Calcium, Ferrous Gluconate, Calcium Carbonate, Eliquis (apixaban), Dapagliflozin, Allopurinol, Venlafaxine HCl (Extended Release 24 Hour), Omeprazole, Levoxyl (levothyroxine), Acetaminophen, Tamsulosin HCl, Bisacodyl, and Methocarbamol, contribute to a shuffling gait in an older adult patient with multiple comorbidities?

Lurasidone is the Most Likely Culprit for Shuffling Gait

Among this medication list, lurasidone (Latuda) poses the highest risk for causing shuffling gait due to extrapyramidal symptoms (EPS), particularly parkinsonism, which directly manifests as shuffling gait, bradykinesia, and rigidity. 1

Primary Offender: Lurasidone

Lurasidone is an atypical antipsychotic that commonly causes extrapyramidal side effects including "difficulty moving, slow movements, muscle stiffness, or tremor" and "restlessness and feeling like you need to move around (akathisia)." 1 These motor symptoms directly produce the shuffling gait pattern characteristic of drug-induced parkinsonism.

Mechanism and Risk Factors

• Lurasidone blocks dopamine D2 receptors in the nigrostriatal pathway, producing parkinsonian symptoms that include shuffling gait, reduced stride length, and bradykinesia 1
• The FDA label explicitly lists falls as a significant adverse effect: "Falls. Lurasidone hydrochloride tablets may make you sleepy or dizzy, may cause a decrease in your blood pressure when changing position (orthostatic hypotension), and can slow your thinking and motor skills which may lead to falls that can cause fractures or other injuries" 1
• Orthostatic hypotension from lurasidone compounds fall risk and gait instability 1

Secondary Contributors

Metoprolol

• Beta-blockers are associated with increased fall risk in elderly patients through multiple mechanisms 2
• The European Society of Cardiology notes that metoprolol can increase neurocognitive impairment in the elderly, potentially affecting gait 2
• Decreased baroreceptor sensitivity in aging increases risk of orthostatic hypotension with antihypertensives, leading to instability and falls 2
• However, metoprolol does not directly cause the shuffling gait pattern characteristic of extrapyramidal symptoms

Venlafaxine

• As a serotonin-norepinephrine reuptake inhibitor (SNRI), venlafaxine is associated with fall risk in elderly patients 2
• Psychotropic medications, including antidepressants, are independent risk factors for falls 2
• Does not typically produce shuffling gait but may contribute to overall gait instability

Methocarbamol

• Central nervous system depression from methocarbamol may cause sedation and impaired motor coordination 3
• The mechanism is general CNS depression without direct action on motor pathways 3
• More likely to cause generalized weakness rather than specific shuffling gait pattern

Critical Context: Polypharmacy Burden

This patient is taking 20 medications, placing them in the "excessive polypharmacy" category (≥10 medications), which dramatically increases adverse drug reaction risk. 2

Compounding Risks

• The risk of adverse drug reactions increases from 13% with 2 medicines to 58% with 5 medicines 2
• Multiple medications affecting the central nervous system (lurasidone, venlafaxine, bupropion, methocarbamol, melatonin) create additive fall risk 2
• Cardiovascular medications (metoprolol, Eliquis, dapagliflozin) combined with CNS-active drugs increase orthostatic hypotension risk 2

Immediate Action Steps

1. Evaluate Lurasidone First

• Assess for extrapyramidal symptoms: bradykinesia, rigidity, tremor, masked facies 1
• Document gait characteristics: stride length, cadence, arm swing, postural stability
• Consider dose reduction or switching to an antipsychotic with lower EPS risk if clinically appropriate 1

2. Assess Orthostatic Hypotension

• Measure blood pressure supine and after 1 and 3 minutes of standing 2, 4
• Orthostatic hypotension is present in 6-33% of elderly syncope cases and commonly causes falls 2
• Multiple medications (metoprolol, lurasidone, tamsulosin, venlafaxine) can contribute 2

3. Medication Review and Deprescribing

• Use STOPP/START criteria or Beers criteria to identify potentially inappropriate medications 2
• Prioritize discontinuing or reducing CNS-active medications that lack clear ongoing indication 2
• Beta-blockers, clonidine, and antipsychotics require careful tapering to avoid withdrawal effects 2

Common Pitfalls to Avoid

• Do not assume shuffling gait is simply "old age" - this is a medication-induced adverse effect until proven otherwise 2
• Do not add medications to treat side effects (prescribing cascade) - the shuffling gait may be misinterpreted as Parkinson's disease, leading to inappropriate dopaminergic therapy 2
• Do not overlook the cumulative burden - while lurasidone is the primary culprit, the combination of 20 medications creates synergistic risk 2
• Do not stop medications abruptly - particularly lurasidone, metoprolol, and venlafaxine require gradual tapering 2