Short answer: Testopel is 75 mg testosterone pellets implanted under the skin, 150 to 450 mg every 3 to 6 months.1 Xyosted is testosterone enanthate injected under the belly skin once a week, starting at 75 mg and adjusted by blood tests.2 The Testopel label says pellets are much less flexible for dose changes. Neither has a boxed warning, and neither label compares the two.
| Testopel | Xyosted | |
|---|---|---|
| How given | 75 mg pellets implanted under the skin1 | Autoinjector under the skin of the belly2 |
| Dose | 150 to 450 mg every 3 to 6 months1 | 75 mg once a week to start; 50, 75 or 100 mg2 |
| How long a dose lasts | Usually three to four months, sometimes six1 | One week2 |
| Adjusting | Two pellets for each 25 mg of weekly injected testosterone propionate needed; hard to change once implanted1 | Trough 7 days after a dose; down 25 mg at 650 ng/dL or more, up 25 mg under 3502 |
| Site problems | Implant site infection and pellets pushing out, mostly in the first month1 | Injection site reactions in 12.7%; no one stopped for them2 |
| Side effect data | Listed without percentages1 | Hematocrit increased 14.0%, hypertension 12.7%, PSA increased 12.0% in a 1-year study2 |
| Boxed warning | None1 | None2 |
About a third of the pellet material is absorbed in the first month, a quarter in the second and a sixth in the third. The Testopel label says pellets are much less flexible for dose changes than pills or injections, and if testosterone must be stopped for a complication, the pellets would have to be removed.1 Xyosted is checked by a trough level after 6 weeks and 6 weeks after any change, and stepped by 25 mg.2
Both share the testosterone warnings: high red blood cells, clots, blood pressure, prostate checks and abuse. Xyosted's label adds depression and suicidal thoughts; Testopel's is also approved to start puberty in selected boys.21
Which, if either, fits is for your prescriber. More detail: Testopel side effects, Xyosted side effects, the Testopel and Xyosted dosing schedules, the Xyosted missed-dose page, the testosterone pellets and testosterone enanthate guides, and Testopel vs testosterone cypionate: how do pellets and injections differ?.