In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: CONCLUSIONS : Although cocaine - associated myocardial ischemia can result from coronary vasoconstriction , patients with cocaine associated chest pain , a non - ischemic ECG , and a TIMI risk score < 2 may be safely discharged from the ED after a negative coronary CTA with a low risk of 30 - day adverse events .
### Output Text:
CONCLUSIONS : Although <span class="chemical">cocaine</span> - associated myocardial ischemia can result from coronary vasoconstriction , patients with <span class="chemical">cocaine</span> associated chest pain , a non - ischemic ECG , and a TIMI risk score < 2 may be safely discharged from the ED after a negative coronary CTA with a low risk of 30 - day adverse events . 