A Study to Assess the Safety, Tolerability, and Pharmacokinetics of Ascending, Subcutaneous, Single and Multiple Doses of SHP681 (Glucagon-like Peptide-2 [GLP-2] Analog-Fc Fusion) in Healthy Adult Participants

Inclusion Criteria

• Ability to voluntarily provide written, signed, and dated informed consent to participate in the study.
• An understanding, ability, and willingness to fully comply with study procedures and restrictions.
• Age 18-50 inclusive at the time of consent. The date of signature of the informed consent is defined as the beginning of the screening period. This inclusion criterion will only be assessed at the first screening visit.
• Male, or non-pregnant, non-lactating female who agrees to comply with any applicable contraceptive requirements of the protocol or females of non-childbearing potential.
• Considered "healthy" by the investigator. Healthy status is defined by absence of evidence of any active or chronic disease or condition based on a detailed medical and surgical history, a complete physical examination including vital signs, 12-lead electrocardiogram (ECG), hematology, blood chemistry, and urinalysis.
• Body mass index between 18.0 kilograms per square meter (kg/m^2) and 30.0 kg/m^2 inclusive with a body weight 50-100 kg (110-220 pounds [lbs]). This inclusion criterion will only be assessed at the first screening visit.

Exclusion Criteria

• History of any hematological, hepatic, respiratory, cardiovascular, renal, neurological or psychiatric disease, gall bladder removal, or current or recurrent disease that could affect the action, absorption, or disposition of the investigational product, or clinical or laboratory assessments.
• Current or relevant history of physical or psychiatric illness, any medical disorder that may require treatment or render the participant unlikely to fully complete the study, or any condition that presents undue risk from the investigational product or procedures.
• Known or suspected intolerance or hypersensitivity to the investigational product(s), closely-related compounds, or any of the stated ingredients.
• Significant illness, as judged by the investigator, within 2 weeks of the first dose of investigational product.
• Known history of alcohol or other substance abuse within the last year.
• Donation of blood or blood products (example [eg], plasma or platelets) within 60 days prior to receiving the first dose of investigational product.
• Within 30 days prior to the first dose of investigational product:
• Have used an investigational product (if elimination half-life is less than ( ) 139 millimeters of mercury (mmHg) or 89mmHg or 450 millisecond (msec) at screening. If QTcF exceeds 450 msec, the ECG should be repeated 2 more times and the average of the 3 QTcF values should be used to determine the participant's eligibility.
• Positive screen for alcohol or illicit drugs at screening or Day -1.
• Male participants who consume more than 21 units of alcohol per week or 3 units per day. Female participants who consume more than 14 units of alcohol per week or 2 units per day.

(1 alcohol unit equal to [=] 1 beer or 1 wine (5 ounce [oz] per 150 milliliter [mL]) or 1 liquor (1.5 oz/40 mL) or 0.75 oz alcohol).

• Positive human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), or hepatitis C virus (HCV) antibody screen.
• Use of tobacco in any form (eg, smoking or chewing) or other nicotine-containing products in any form (eg, gum, patch). Ex-users must report that they have stopped using tobacco for at least 30 days prior to receiving the first dose of investigational product.
• Routine consumption of more than 2 units of caffeine per day or participants who experience headaches associated with caffeine withdrawal. (1 caffeine unit is contained in the following items: one 6 oz (180 mL) cup of coffee, two 12 oz (360 mL) cans of cola, one 12 oz cup of tea, three 1 oz (85 g) chocolate bars. Decaffeinated coffee, tea, or cola are not considered to contain caffeine).
• Prior screen failure (unless Sponsor approval is given), randomization, participation, or enrollment in this study or prior exposure to any GLP-2 analogs.
• Unresected gastrointestinal (