The concentration of delta sleep-inducing peptide (DSIP), also known as emideltide, can be calculated by dividing the declared amount of peptide in the vial by the final volume of the solution. However, there is no validated universal reconstitution volume, approved clinical dose, or established protocol for self-administration of DSIP by injection.
This distinction is crucial when using any DSIP dosage calculator. The calculator can correctly convert units and calculate the concentration. However, it cannot confirm that the vial actually contains the amount stated on the label. Nor is it able to select the appropriate liquid, confirm sterility, determine stability after mixing, or establish what amount would be safe or effective for a human.
DSIP is a peptide consisting of nine amino acids with the sequence Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu. Its empirical formula is C35H48N10O15, and its molecular mass is approximately 848.8 g/mol [1]. DSIP is not a drug approved by the FDA or the EMA. Commercially available 5 mg and 10 mg DSIP vials are therefore not approved dosage forms.
In the article, we explain the mathematics behind concentration calculation, without presenting instructions for self-application. In the examples, we use exclusively hypothetical final volumes to show how the concentration changes. These are not recommendations regarding the amount of bacteriostatic water, the amount of DSIP, the injection site, or the frequency of administration.
The DSIP concentration calculator for research purposes works on the same principle. It exclusively calculates mg/mL and mcg/mL. It does not calculate individual doses, syringe units or body weight-dependent schedules.
What does DSIP reconstitution mean?
Reconstitution means adding the appropriate liquid to a dry preparation in order to obtain a solution or suspension of a specified final concentration.
A vial labelled as „DSIP 5 mg” or „DSIP 10 mg” often contains freeze-dried powder, which is freeze-dried. Freeze-drying removes water under controlled conditions. This process can improve the physical and chemical stability of certain peptides in the dry state.
Freeze-drying does not automatically mean, however, that the product is sterile, of pharmaceutical quality, contains the exact declared amount of the substance, or is suitable for human use.
The term „DSIP reconstitution” is often used on the internet as if there were one standard procedure. From a scientific point of view, this is not the case.
A complete reconstitution method would have to specify the identity and chemical form of the peptide, verified quantity and purity, composition and pH of the liquid, intended final volume, type of container, mixing conditions, temperature, light exposure, microbiological control, analytical requirements and intended use.
General pharmaceutical studies show that the stability of peptides and proteins can vary significantly after transitioning a dry product into a liquid form. Influencing factors may include pH, buffers, excipients, oxygen, light, temperature, surface contact, agitation, concentration, and freeze-thaw cycles [2].
A simple calculation involving „5 mg” and „2 mL” does not contain any of this formulation information.
Reconstitution also differs from dilution. Reconstitution starts with a dry material and results in a liquid preparation. Dilution, on the other hand, starts with an existing solution and decreases its concentration by adding more fluid.
In both cases, the final total volume is an important value. It does not always have to be exactly the same as the initially added amount of liquid. In precise laboratory studies, the final volume is determined using validated procedures and calibrated equipment.
Why is the vial size not the same as the administered dose?
The term „5 mg vial” means that the container is labelled as containing 5 mg of material. It does not mean that 5 mg is the appropriate dose.
The same rule applies to the 10 mg and 15 mg vials.
The mass of the vial contents, concentration, portion volume and administered amount are different parameters.
| Parameter | What does it describe | Typical unit | What it does not specify |
|---|---|---|---|
| Declared mass in the vial | The declared mass of the material in the unopened vial | mg | Identity, purity, sterility nor a safe dose |
| Final volume | Total volume after preparation | ml | Neither compatibility nor stability |
| Concentration | Mass per unit volume | mg/mL or mcg/mL | Clinical utility |
| Portion size | Volume taken for the laboratory procedure | mL or µL | Human doses |
| Portion weight | Concentration multiplied by the portion volume | mg or mcg | Safety, efficacy, nor appropriate route of administration |
The vial label itself may also require careful interpretation. The declared quantity may differ from the quantity actually determined analytically.
A certificate of analysis may state the purity of the peptide, but it does not necessarily confirm sterility, endotoxin levels, the presence of residual solvents, water content, counterions, particulate matter or fill volume accuracy.
DSIP can also be supplied as a free peptide or in a form containing a counter-ion, for example acetate. These forms may have different molecular weights. Therefore, „5 mg of powder” does not always mean exactly „5 mg of active DSIP calculated as the free peptide”.
In the case of regulated pharmaceutical products, these issues are controlled through approved specifications and validated testing. A product intended for research use only may not be subject to the same requirements.
For this reason, a body weight-based DSIP dosage calculator also cannot determine a safe human dose. Multiplying body weight by a value expressed in mcg/kg is a simple mathematical operation. However, choosing the appropriate mcg/kg value requires clinical trials, pharmacokinetic data, information on bioavailability for a specific route of administration, safety data, formulation, and appropriate manufacturing standards.
Available data regarding DSIP does not provide a modern, approved standard dosage.
DSIP 5 mg reconstitution calculations
For the vial labelled as 5 mg, the concentration is calculated by dividing 5 mg by the final volume.
Concentration (mg/mL) = 5 mg ÷ final volume (mL)
To convert mg/mL to mcg/mL, the result must be multiplied by 1000, because 1 mg is equivalent to 1000 mcg.
The following examples use hypothetical final volumes. They merely show how to perform calculations. They do not constitute instructions for adding such quantities of liquid to the DSIP vial.
| Declared mass in the vial | Hypothetical final volume | Calculated concentration | Concentration in mcg/mL |
|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 5000 mcg/mL |
| 5 mg | 2 mL | 2.5 mg/mL | 2500 mcg/mL |
| 5 mg | 2.5 mL | 2 mg/mL | 2000 mcg/mL |
| 5 mg | 5 mL | 1 mg/mL | 1000 mcg/mL |
The table shows the basic principle: changing the volume changes the concentration, but does not change the nominal total mass of 5 mg.
If the final volume is doubled, the concentration will be halved. If the volume is halved, the concentration will double.
However, this does not mean that a more concentrated or more diluted preparation is safer, better, more stable or more appropriate. Answering such questions requires formulation data, not just calculations.
For example, entering a value of 5 mg and a hypothetical final volume of 2 mL into the calculator gives a result of 2.5 mg/mL, or 2500 mcg/mL.
This result assumes that the vial actually contains 5 mg of the appropriate form of DSIP, all the material has been dissolved, there have been no significant losses, and the actual final volume is exactly 2 mL. The calculator cannot verify any of these assumptions.
DSIP 10 mg reconstitution calculation
The same formula applies to the vial labelled as 10 mg:
Concentration (mg/mL) = 10 mg ÷ final volume (mL)
If the final volume remains the same, a 10 mg vial gives twice the nominal concentration of a 5 mg vial.
| Declared mass in the vial | Hypothetical final volume | Calculated concentration | Concentration in mcg/mL |
|---|---|---|---|
| 10 mg | 1 mL | 10 mg/mL | 10,000 mcg/mL |
| 10 mg | 2 mL | 5 mg/mL | 5000 mcg/mL |
| 10 mg | 2.5 mL | 4 mg/mL | 4000 mcg/mL |
| 10 mg | 5 mL | 2 mg/mL | 2000 mcg/mL |
A common mistake is to assume that a „10 mg vial” means that every volume withdrawn from the vial contains 10 mg. This is not the case.
The 10 mg value refers to the nominal total amount of material in the container prior to preparation. If the hypothetical final volume is 5 mL, the calculated concentration is 2 mg/mL. The entire 5 mL would nominally contain 10 mg, whereas smaller portions would contain a proportionally smaller amount.
This is solely an explanation of the mass balance. It does not constitute a recommendation regarding the intake or administration of any quantity.
Another common error is applying the calculations for a 5 mg vial to a 10 mg vial without changing the value in the numerator. At the same final volume, the 10 mg vial will have twice the concentration.
Based solely on the mathematical relationship, it is not possible to determine whether any of these concentrations are chemically appropriate.
Formula for concentration: mg, mcg, mL and syringe units
Basic concentration calculations look like this:
mg/mL = mass in mg ÷ final volume in mL
mcg/mL = mg/mL × 1000
Mass in a laboratory portion = concentration × volume of the portion
The units must remain consistent throughout the calculation.
If the concentration is given in mcg/mL, the volume when calculating micrograms should be expressed in mL. If the volume is given in microlitres, it must first be converted:
1000 µL = 1 mL
For example, 250 µL corresponds to 0.25 mL.
These are standard laboratory unit conversions, not DSIP administration instructions.
Special care is required with „syringe units”, as the markings on the syringe indicate volume rather than the mass of the peptide.
For example, a U-100 insulin syringe is graduated as 100 units per millilitre. One marked unit therefore corresponds to 0.01 mL. This describes exclusively the scale of the device. It does not mean that one unit on the syringe corresponds to a fixed amount of DSIP.
The amount of peptide contained in a given volume varies with the concentration. Other syringes may also have a different calibration.
For this reason, the calculator described here stops short of converting the target human dose into syringe markings. Such an action would turn a concentration calculator into a practical guide for injecting an unapproved substance.
In laboratory research, the molar concentration may also be useful. The molecular mass of native DSIP is approximately 848.8 g/mol [1].
For example, 1 mg/mL corresponds to 1 g/L. Dividing 1 g/L by 848.8 g/mol gives approximately 0.00118 mol/L, or 1.18 mM for native free DSIP.
If the material is an acetate, a hydrate, a preparation with a specific impurity content, or another chemical form, using the value of 848.8 g/mol without appropriate correction may lead to an incorrect calculation of the molar concentration.
How much bacteriostatic water? Why is there no single universal answer?
There is no peer-reviewed or regulatory-approved universal amount of bacteriostatic water for a 5 mg or 10 mg DSIP vial.
The volume of liquid affects the concentration, but the correct formulation cannot be selected solely on the basis of the vial size.
Also important are the verified chemical form of DSIP, solubility, pH, buffer requirements, target concentration, planned analytical method, container type, compatibility, microbiological control and stability.
Bacteriostatic Water for Injection is a specific product containing an antimicrobial preservative, most commonly benzyl alcohol. Sterile Water for Injection contains no such preservative.
These products should not automatically be treated as interchangeable. More importantly, adding either of them to an unapproved research peptide does not make it suitable for injection.
The preservative may limit the growth of certain microorganisms. However, it does not remove existing contamination, eliminate endotoxins, sterilise non-sterile peptide powder, nor guarantee chemical stability or compatibility.
Official safety recommendations regarding injections also indicate that preservatives present in multidose vials do not provide complete protection against bacterial contamination and do not protect against viruses [3].
Internet instructions often feature one or two millilitres, as such volumes make calculations easier. Convenient mathematics is not, however, the same as a validated pharmaceutical formulation.
A test vial of uncertain identity or sterility remains a product with uncertain properties, regardless of whether the calculated concentration is 1 mg/mL, 2.5 mg/mL or 5 mg/mL.
In legitimate laboratory testing, the type of liquid and the final volume should derive from the specific test protocol, based on appropriate solubility and stability data.
How do DSIP’s online dosing calculators work?
Most online peptide calculators combine several basic mathematical relationships.
First, the mass of the vial contents divided by the final volume gives the concentration. Then, the chosen mass divided by the concentration can give a specific volume. Some calculators then convert this volume into syringe markings.
The calculator described here deliberately covers only the first stage.
It accepts 5 mg, 10 mg or a custom mass for research purposes along with a user-provided final volume. It then calculates the resulting concentration in mg/mL and mcg/mL.
It does not select the final volume. It does not ask for body weight, does not recommend mcg/kg values, does not calculate the injection volume and does not convert the dose into insulin syringe units. It also does not explain how to physically prepare a 5 mg or 10 mg DSIP vial.
These restrictions are intentional. A mathematically correct result may be medically misleading if the dose, route of administration, formulation or quality of the product have not been established.
A well-designed concentration calculator should clearly present the formula, maintain correct units, reject zero and negative values, and explain the adopted assumptions.
It should also distinguish between the quantity stated on the vial and the verified content of the active substance. If laboratory analysis shows a quantity other than that declared on the label, properly conducted studies may require the use of the analytically determined value and the inclusion of purity and chemical form in accordance with a validated method.
Simply entering the value from the label may otherwise create a false impression of precision.
Most common errors in calculations and unit conversion
Many significant errors are of a conceptual rather than a mathematical nature.
The most common errors include confusing milligrams with micrograms, treating the volume of the added liquid as exactly equal to the final volume, interpreting the markings on a syringe as the mass of the peptide, and assuming that the value on the vial label corresponds to a verified laboratory assay.
One milligram is equal to 1,000 micrograms.
It is not equivalent to 100 micrograms.
An error involving a factor of 1,000 can therefore lead to a very large difference. It is equally important to place the decimal point correctly:
0.1 mg = 100 mcg
0.01 mg = 10 mcg
Using a zero before the decimal point for values less than unity can reduce the risk of errors. For example, 0.5 mg is clearer than ,5 mg. It is also advisable to avoid unnecessary trailing zeros: 5 mg is a better written form than 5.0 mg, unless additional precision is intended.
Another potential error relates to the final volume. Adding 2 mL of liquid does not necessarily mean that the resulting preparation will have a final volume of exactly 2 mL. Dry material, incomplete transfer, residual liquid and the accuracy of measuring instruments can all affect the precision of the analytical preparation.
Calculations relating to purity may also be misinterpreted. A statement such as „99% purity”, based on the percentage of the surface area occupied by HPLC peaks, does not necessarily mean that 99% of the total weight of the vial consists of the active peptide.
The interpretation may be affected by water, counter-ions, solvent residues and substances that cannot be detected by the same method. Identity testing, quantification and purity analysis address different issues. The chromatogram alone does not confirm the quantity of material in the vial, sterility or endotoxin levels.
Rounding can also be a source of errors. It is usually better to round the result only at the end of the calculation, rather than at every intermediate stage. The number of decimal places displayed should also correspond to the accuracy of the original measurements.
Finally, doubling the size of the vial does not mean that any dose should automatically be doubled. A 10 mg vial at the same hypothetical final volume as a 5 mg vial has twice the concentration. If its final volume is also doubled, the concentration will remain the same.
None of these calculations specifies an appropriate therapeutic dose.
Storage and stability of DSIP following reconstitution
In the available scientific data, an independently validated, universal shelf life for a typical commercial 5 mg or 10 mg DSIP research vial after reconstitution has not been established.
Therefore, claims such as „stable for 14 days”, „stable for 21 days” or „stable for 28 days” should not be treated as universal scientific facts.
Vendor recommendations may be based on internal testing, assumptions or commonly repeated practices. They are not equivalent to peer-reviewed stability studies carried out for the exact same formulation and container.
The frequently cited 28-day period can also be misinterpreted. The CDC guidelines, which refer to USP standards, state that an opened, multi-dose vial labelled by the manufacturer is usually dated and discarded within 28 days, unless the manufacturer has specified a different period [3].
This is a guideline concerning appropriate multidose medication vials. It does not prove that a self-prepared DSIP solution remains chemically stable, active, pure and sterile for 28 days.
The use of bacteriostatic water does not turn the research product into an approved multi-dose medicine.
Chemical stability and microbiological safety should also be considered separately.
The solution may remain clear even though the peptide undergoes degradation, oxidation, hydrolysis, isomerisation, adsorption onto a surface or aggregation. The opposite situation is also possible: the peptide may remain chemically intact, whilst the preparation becomes microbiologically hazardous.
General biopharmaceutical studies indicate temperature, pH, oxygen, light, agitation, ionic strength, container interactions and formulation composition as significant factors affecting stability [2].
One peer-reviewed in vitro study regarding the blood–brain barrier found relatively little degradation of DSIP during the experimental diffusion process [4]. However, the study utilised a specific cell culture system, experimental medium and analytical method. It was not a refrigerator storage study and does not establish how long a commercial DSIP solution remains stable once prepared.
Similarly, the plasma half-life or in vivo degradation data do not make it possible to determine the stability period of the prepared vial during storage.
A reliable assessment of stability would require a defined formulation, a validated method demonstrating stability – such as an appropriate HPLC or LC-MS analysis – specified temperatures and time points, a defined container-closure system–closure system, acceptance criteria and, where applicable, microbiological testing.
Without such data, it is not possible to provide a universal, evidence-based answer to the question of how long DSIP remains stable after reconstitution.
Sterility and risk of contamination
Sterility cannot be determined by the appearance of the freeze-dried powder, a seemingly tight stopper, the percentage purity value or the designation „research grade”.
Chemical purity and microbiological quality are two different properties.
A peptide can exhibit high chemical purity while simultaneously containing microorganisms, endotoxins, particulate matter or other contaminants. Endotoxins can remain present even when living bacteria are no longer detectable. The addition of sterile or bacteriostatic water does not remove endotoxins and does not render a non-sterile product sterile.
Official CDC guidelines link unsafe injection practices to bacterial and fungal infections, as well as the transmission of hepatitis B and C viruses, and HIV [3,5]. Healthcare standards therefore require strict aseptic procedures and the proper handling of single- and multi-dose products.
These standards should not be interpreted as instructions for the home preparation of DSIP. A research product without approved information indicating that it is sterile and intended for injection should not automatically be treated as an injectable medicine.
It is also important to distinguish between single-dose and multi-dose containers. A vial designated by the manufacturer as single-dose is generally intended for single use and may not contain an antimicrobial agent. A true multi-dose vial is specifically designed and labelled for repeated withdrawal and typically contains a preservative, although this still only provides limited protection [3].
A commercial research peptide vial does not need to be designed or validated as either of these types of approved pharmaceutical packaging.
Visual inspection can detect some obvious problems. Cloudiness, the presence of particles, discoloration, leakage or damaged packaging may indicate that the product should be rejected. However, a clear solution does not confirm sterility, correct concentration or chemical stability.
Significant impurities and degradation products may be invisible.
For this reason, the article does not present needle sizes, injection sites, methods of piercing the stopper, physical mixing instructions or methods of preparing the nasal spray.
What can a calculator determine, and what can it not?
The DSIP concentration calculator is reliable solely within the scope of the mathematical relationship between the entered values.
If the vial contains a mass M, and the actual final volume is V, then:
Concentration = n ÷ V
The calculator is not a chemical assay method, sterility test, stability study, drug prescription system, or clinical decision-making tool.
| Question | Can a calculator answer them? | Why? |
|---|---|---|
| What is the nominal concentration in mg/mL for the given mass and final volume? | Yes | Direct mathematical calculation |
| What is the concentration in mcg/mL? | Yes | Conversion of units according to 1 mg = 1000 mcg |
| How much liquid should be added to DSIP? | Not | It requires a validated formulation and a specific application |
| What dose should the person take? | Not | There is no approved dosage standard for DSIP |
| How many units on the syringe should be injected? | Not | It would require an unconfirmed dose and device-specific instructions |
| Is the vial sterile and correctly filled? | Not | Requires quality control testing |
| How long will the solution remain stable? | Not | It requires chemical and microbiological data concerning a specific product |
| Is a 5 mg or 10 mg vial safe? | Not | The size of the vial does not determine identity, quality, safety or efficacy. |
Limitations of the available evidence
Scientific evidence regarding the reconstitution of DSIP is significantly more limited than the large number of protocols available online might suggest.
Published DSIP research mainly concerns biological effects, chemical identity, transport or experimental pharmacology. It does not provide the contemporary standard of pharmaceutical formulation for commercial 5 mg and 10 mg research vials.
The analysed data do not include an FDA- or EMA-approved product characteristic for DSIP, a standardised solvent, a universal final concentration, or a product-specific shelf-life after reconstitution.
General research into peptide and protein formulation helps to identify potential stability and quality issues, but cannot provide DSIP-specific values without testing the specific formulation.
DSIP is a small linear peptide, rather than a large therapeutic protein. Not all problems concerning protein stability will therefore have the same significance. A smaller size does not, however, eliminate the possibility of hydrolysis, oxidation, adsorption, isomerisation, enzymatic degradation or microbial contamination.
The tables for 5 mg and 10 mg presented in this article are therefore purely mathematical examples. They assume full recovery of the declared mass and a precisely defined final volume.
They do not take into account chemical form, purity, water content, over- or under-filling, adsorption, incomplete dissolution or analytical uncertainty. They should not be interpreted as dosage tables.
FAQ: DSIP reconstitution and calculations
Is there an official DSIP reconstitution chart?
No. There is no universally established DSIP reconstitution table approved by regulatory bodies. Tables available on the internet are often based on convenient mass-to-volume calculations rather than validated pharmaceutical formulations. The tables in this article are clearly hypothetical and are intended solely for concentration calculation purposes.
How to calculate the concentration of DSIP from a 5 mg vial?
Divide 5 mg by the specified final volume in millilitres. For example, a hypothetical final volume of 2 mL gives a nominal concentration of 2.5 mg/mL, or 2,500 mcg/mL. This is solely a mathematical example and not a recommendation to add 2 mL of liquid or to use the resulting preparation in humans.
How to calculate the concentration of DSIP from a 10 mg vial?
10 mg must be divided by the specified final volume in millilitres. For example, a hypothetical final volume of 5 mL gives 2 mg/mL, or 2000 mcg/mL. It cannot be determined from the calculation alone whether such a volume is appropriate for a specific product.
Does 5 mg or 10 mg mean the DSIP dose?
No. These values usually describe the nominal total amount of material contained in the vial. The clinical dose would have to be established for the specific individual, route of administration, formulation, indication and regimen. DSIP does not have an FDA- or EMA-approved dosage standard for humans.
Can the DSIP dosage calculator take body weight into account?
The calculator can mathematically multiply body weight by the chosen mcg/kg value, but it is unable to determine whether such a value is safe or appropriate. An evidence-based calculation would require a validated dose, route of administration, formulation, safety limits and a monitoring plan. These have not been established for the approved use of DSIP.
Does bacteriostatic water make DSIP stable for 28 days?
No. The frequently cited 28-day rule applies to appropriately labelled multidose vials, unless the manufacturer has specified a different period [3]. It does not prove that the prepared DSIP solution remains chemically stable, active and sterile for 28 days.
Are sterile water and bacteriostatic water interchangeable?
No. Sterile Water for Injection contains no preservative, whereas Bacteriostatic Water for Injection contains a preservative. The correct choice depends on the formulation, route of administration, intended use, compatibility, and approved instructions. Neither of these products should be chosen for an unapproved peptide solely on the basis of an online calculator.
How many micrograms are in 5 mg and 10 mg?
5 mg is equivalent to 5000 mcg. 10 mg is equivalent to 10,000 mcg. These are simple conversions of nominal total mass and do not constitute recommended doses.
Do units on an insulin syringe correspond to micrograms of DSIP?
No. The units on the syringe represent a calibrated volume, whereas micrograms indicate mass. The relationship between them changes with the concentration of the solution and the calibration of the syringe. The article does not present calculations for the volume of DSIP injection.
Can DSIP be frozen or stored in the fridge after reconstitution?
Without specific product stability data, there is no universal, evidence-based storage instruction. Refrigeration and freezing can affect chemical degradation, precipitation, adsorption, and freeze-thaw cycle behaviour differently depending on the formulation and container.
Does a clear DSIP solution mean that it is safe?
No. Appearance does not allow confirmation of peptide identity, concentration, sterility, endotoxin levels or chemical integrity. Significant impurities and degradation products may be invisible.
Disclaimer
This article and the accompanying calculator are intended solely for educational purposes and non-clinical mathematical calculations. They do not contain instructions for reconstitution, preparation, dosing or injection, and should not be construed as medical advice.
Delta sleep-inducing peptide (DSIP/emideltide) is not approved by the US Food and Drug Administration (FDA) or the European Medicines Agency (EMA) as a medicinal product for sleep disorders, for self-administration, or for the reconstitution practices discussed in this article. Available data are limited and include preclinical, mechanistic, and small or historical human studies.
References
[1] National Center for Biotechnology Information. (2026). PubChem compound summary for CID 68816, delta sleep-inducing peptide. PubChem. https://pubchem.ncbi.nlm.nih.gov/compound/68816
[2] Manning, M. C., Chou, D. K., Murphy, B. M., Payne, R. W., & Katayama, D. S. (2010). Stability of protein pharmaceuticals: An update. Pharmaceutical Research, 27(4), 544–575. https://doi.org/10.1007/s11095-009-0045-6
[3] Centres for Disease Control and Prevention. (2024). Preventing unsafe injection practices. https://www.cdc.gov/injection-safety/hcp/clinical-safety/index.html
[4] Raeissi, S., & Audus, K. L. (1989). In-vitro characterisation of blood-brain barrier permeability to delta sleep-inducing peptide. Journal of Pharmacy and Pharmacology, 41(12), 848–852. https://doi.org/10.1111/j.2042-7158.1989.tb06385.x
[5] Centres for Disease Control and Prevention. (2024). Safe injection practices to prevent transmission of infections to patients. https://www.cdc.gov/injection-safety/hcp/clinical-guidance/index.html