What substance is most likely responsible for the paranoid behavior and agitation in a 36-year-old man with a history of substance abuse, presenting with hostility, paranoia, and evidence of intravenous (IV) drug use, as indicated by track marks on the left antecubital fossa?

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Differential Diagnosis

  • Single most likely diagnosis
    • A) Amphetamine: The patient's agitation, paranoia, and hostility are consistent with amphetamine-induced psychosis. The presence of track marks on the left antecubital fossa also suggests intravenous drug use, which is a common route of administration for amphetamines.
  • Other Likely diagnoses
    • C) Ketamine: Ketamine can cause dissociative symptoms, hallucinations, and paranoia, which may contribute to the patient's behavior. However, ketamine-induced psychosis is less likely to present with the same level of hostility and aggression as amphetamine-induced psychosis.
    • E) Opioid: Opioid withdrawal can cause irritability, anxiety, and agitation, which may contribute to the patient's behavior. However, the presence of track marks and the patient's refusal to answer questions about intravenous drug use suggest that opioid use may be a contributing factor.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • None of the options are immediately life-threatening, but it's essential to consider the potential for overdose or withdrawal from any substance, particularly opioids, which can be fatal if not addressed promptly.
  • Rare diagnoses
    • B) Benzodiazepine: Benzodiazepine withdrawal can cause anxiety, agitation, and paranoia, but it is less likely to present with the same level of hostility and aggression as amphetamine-induced psychosis.
    • D) Marijuana: Marijuana use can cause paranoia and anxiety, but it is less likely to contribute to the patient's aggressive behavior and hostility.

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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