Abacavir Sulfate side effects: what 9,685 FDA adverse event reports show
Drug class
Not stated in label
Who reports
9,685 reports · 93% serious · 1,180 with death outcome · 37% female
Used for
Abacavir tablet, a nucleoside analogue human immunodeficiency virus (HIV-1) reverse transcriptase inhibitor, is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. Abacavir tablets USP 300 mg, in combination with other antiretroviral agents, are indicated for the treatment of human immunodeficiency virus (HIV-1) infection.
What it is
Abacavir sulfate is a synthetic carbocyclic nucleoside analogue with inhibitory activity against HIV-1.
Boxed warning
HYPERSENSITIVITY REACTIONS WARNING: HYPERSENSITIVITY REACTIONS See full prescribing information for complete boxed warning. Serious and sometimes fatal hypersensitivity reactions have occurred with abacavir sulfate. ( 5.1 ) Hypersensitivity to abacavir is a multi-organ clinical syndrome.
Causality screen of the 40 strongest signals
What the badges mean
- Labeled — boxed warning The term (or its clinical synonym) appears in the FDA boxed warning: causality is regulator-recognised and considered serious.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 1,004 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Progressive external ophthalmoplegia | 94 | 5,735.5 3,892.6–8,450.9ROR 5,791.7 · χ² 144,676 / p <1e-300 | 1,179.5 EB05 992.6 · IC025 +7.1 3/3 methods agree | Not in label — unassessed | serious n=94 · ♀ 0% (drug 37%) · 95% clinician | not reported in cached trials |
| Retroperitoneal disorder | 10 | 1,941.4 824.7–4,570.3ROR 1,943.4 · χ² 9,167 / p <1e-300 | 345.0 EB05 200.3 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Immunodeficiency congenital | 10 | 1,423.7 639.8–3,168.3ROR 1,425.2 · χ² 7,698 / p <1e-300 | 324.2 EB05 188.2 · IC025 +3.3 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=10 | not reported in cached trials |
| Total lung capacity increased | 99 | 1,236.4 966.1–1,582.4ROR 1,249.1 · χ² 76,616 / p <1e-300 | 679.8 EB05 574.6 · IC025 +7.0 3/3 methods agree | Not in label — unassessed | serious n=99 · ♀ 100% (drug 37%) · 94% clinician | not reported in cached trials |
| Peritoneal thickening | 10 | 1,186.4 547.8–2,569.5ROR 1,187.7 · χ² 6,871 / p <1e-300 | 310.2 EB05 180.1 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Genetic polymorphism | 20 | 1,154.4 670.3–1,988.1ROR 1,156.7 · χ² 14,221 / p <1e-300 | 435.9 EB05 297.9 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=20 | not reported in cached trials |
| Hiv associated nephropathy | 15 | 915.2 500.0–1,675.3ROR 916.7 · χ² 8,960 / p <1e-300 | 352.4 EB05 226.7 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=15 | not reported in cached trials |
| Aids encephalopathy | 15 | 745.0 414.0–1,340.4ROR 746.1 · χ² 7,720 / p <1e-300 | 324.0 EB05 208.4 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=15 | not reported in cached trials |
| Astrocytoma malignant | 20 | 569.5 347.9–932.2ROR 570.7 · χ² 8,517 / p <1e-300 | 314.4 EB05 214.9 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=20 | not reported in cached trials |
| Asthma-chronic obstructive pulmonary disease overlap syndrome | 99 | 509.4 409.5–633.7ROR 514.7 · χ² 40,153 / p <1e-300 | 381.1 EB05 322.2 · IC025 +6.7 3/3 methods agree | Labeled (related wording) related wording | serious n=99 · ♀ 100% (drug 37%) · 94% clinician | not reported in cached trials |
| Csf hiv escape syndrome | 24 | 449.6 289.6–697.9ROR 450.7 · χ² 8,507 / p <1e-300 | 286.7 EB05 202.8 · IC025 +4.8 3/3 methods agree | Not in label — unassessed | serious n=24 · 100% clinician | not reported in cached trials |
| Mitochondrial toxicity | 138 | 437.3 364.5–524.6ROR 443.6 · χ² 49,497 / p <1e-300 | 345.7 EB05 299.9 · IC025 +7.0 3/3 methods agree | Not in label — unassessed | serious n=138 · ♀ 5% (drug 37%) · 90% clinician | not reported in cached trials |
| Hiv viraemia | 28 | 335.9 225.6–500.1ROR 336.9 · χ² 7,792 / p <1e-300 | 242.4 EB05 176.0 · IC025 +4.9 3/3 methods agree | Not in label — unassessed | serious n=28 · 100% clinician | not reported in cached trials |
| Lipodystrophy acquired | 286 | 335.6 296.7–379.5ROR 345.8 · χ² 82,170 / p <1e-300 | 284.6 EB05 258.0 · IC025 +7.4 3/3 methods agree | Not in label — unassessed | serious n=279 · ♀ 17% (drug 37%) | not reported in cached trials |
| Temperature regulation disorder | 246 | 274.9 241.1–313.5ROR 282.0 · χ² 59,243 / p <1e-300 | 239.2 EB05 215.1 · IC025 +7.1 3/3 methods agree | Not in label — unassessed | serious n=246 · ♀ 100% (drug 37%) | not reported in cached trials |
| Congenital intestinal malformation | 12 | 246.4 135.6–447.7ROR 246.7 · χ² 2,414 / p <1e-300 | 163.9 EB05 99.9 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=12 | not reported in cached trials |
| Viral mutation identified | 358 | 231.3 207.7–257.4ROR 240.1 · χ² 73,861 / p <1e-300 | 206.5 EB05 189.1 · IC025 +7.2 3/3 methods agree | Not in label — unassessed | serious n=357 · 99% clinician | not reported in cached trials |
| Foetal growth abnormality | 15 | 224.0 131.6–381.2ROR 224.4 · χ² 2,816 / p <1e-300 | 161.5 EB05 103.9 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious n=15 | not reported in cached trials |
| Mitochondrial myopathy | 20 | 217.9 137.6–345.1ROR 218.4 · χ² 3,724 / p <1e-300 | 166.6 EB05 113.9 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious n=19 | not reported in cached trials |
| Virologic failure | 490 | 216.4 197.6–236.9ROR 227.9 · χ² 95,214 / p <1e-300 | 195.1 EB05 181.0 · IC025 +7.2 3/3 methods agree | Not in label — unassessed | serious n=489 · 98% clinician | not reported in cached trials |
| Hiv-associated neurocognitive disorder | 10 | 211.4 110.4–404.8ROR 211.7 · χ² 1,719 / p <1e-300 | 141.3 EB05 82.0 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Immune reconstitution syndrome | 102 | 183.2 149.8–224.0ROR 185.1 · χ² 16,856 / p <1e-300 | 163.7 EB05 138.7 · IC025 +6.2 3/3 methods agree | Labeled — boxed warning exact term | serious n=99 | not reported in cached trials |
| Dandy-walker syndrome | 19 | 170.5 106.9–271.9ROR 170.8 · χ² 2,810 / p <1e-300 | 136.6 EB05 92.4 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious n=19 | not reported in cached trials |
| Facial wasting | 16 | 138.3 83.5–229.3ROR 138.6 · χ² 1,922 / p <1e-300 | 112.8 EB05 73.6 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious n=15 | not reported in cached trials |
| Mitochondrial cytopathy | 25 | 129.0 86.2–193.0ROR 129.3 · χ² 2,874 / p <1e-300 | 111.5 EB05 79.4 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=25 | not reported in cached trials |
| Bone demineralisation | 56 | 120.6 92.2–157.7ROR 121.3 · χ² 6,172 / p <1e-300 | 110.0 EB05 87.9 · IC025 +5.4 3/3 methods agree | Not in label — unassessed | serious n=52 | not reported in cached trials |
| Macrocephaly | 20 | 119.6 76.3–187.6ROR 119.9 · χ² 2,117 / p <1e-300 | 102.5 EB05 70.1 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious n=20 · 100% clinician | not reported in cached trials |
| Foetal death | 266 | 117.1 103.7–132.3ROR 120.4 · χ² 28,925 / p <1e-300 | 110.2 EB05 99.5 · IC025 +6.3 3/3 methods agree | Not in label — unassessed | serious n=266 · ♀ 100% (drug 37%) · 92% clinician | not reported in cached trials |
| Lipoatrophy | 47 | 112.9 84.3–151.3ROR 113.4 · χ² 4,846 / p <1e-300 | 102.9 EB05 80.5 · IC025 +5.2 3/3 methods agree | Not in label — unassessed | serious n=46 | not reported in cached trials |
| Polydactyly | 56 | 110.4 84.5–144.3ROR 111.1 · χ² 5,671 / p <1e-300 | 101.5 EB05 81.1 · IC025 +5.3 3/3 methods agree | Not in label — unassessed | serious n=57 · ♀ 0% (drug 37%) | not reported in cached trials |
| Blood hiv rna increased | 86 | 109.1 87.9–135.3ROR 110.0 · χ² 8,659 / p <1e-300 | 101.5 EB05 84.8 · IC025 +5.7 3/3 methods agree | Lab value / disease marker | serious n=84 | not reported in cached trials |
| Hypomania | 173 | 106.6 91.6–124.0ROR 108.5 · χ² 17,134 / p <1e-300 | 100.4 EB05 88.5 · IC025 +6.0 3/3 methods agree | Not in label — unassessed | serious n=173 · ♀ 100% (drug 37%) · 96% clinician | not reported in cached trials |
| Atrioventricular septal defect | 22 | 105.1 68.5–161.2ROR 105.3 · χ² 2,064 / p <1e-300 | 92.4 EB05 64.3 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious n=22 · 95% clinician | not reported in cached trials |
| Human immunodeficiency virus transmission | 12 | 104.6 58.6–186.7ROR 104.7 · χ² 1,077 / p 2e-236 | 86.5 EB05 52.7 · IC025 +3.4 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=12 | not reported in cached trials |
| Renal aneurysm | 11 | 103.0 56.3–188.6ROR 103.1 · χ² 965 / p 3e-212 | 84.4 EB05 50.3 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious n=11 | not reported in cached trials |
| Food allergy | 343 | 103.0 92.6–114.6ROR 106.7 · χ² 32,961 / p <1e-300 | 97.8 EB05 89.4 · IC025 +6.2 3/3 methods agree | Not in label — unassessed | serious n=343 · ♀ 100% (drug 37%) | not reported in cached trials |
| Immune reconstitution inflammatory syndrome | 223 | 100.9 88.4–115.3ROR 103.3 · χ² 20,979 / p <1e-300 | 95.7 EB05 85.6 · IC025 +6.1 3/3 methods agree | Labeled (related wording) related wording | serious n=223 · 91% clinician | not reported in cached trials |
| Jaundice cholestatic | 157 | 100.4 85.7–117.7ROR 102.1 · χ² 14,671 / p <1e-300 | 94.9 EB05 83.1 · IC025 +5.9 3/3 methods agree | Not in label — unassessed | serious n=157 · ♀ 100% (drug 37%) · 96% clinician | not reported in cached trials |
| Kaposi's sarcoma | 22 | 97.7 63.7–149.7ROR 97.9 · χ² 1,922 / p <1e-300 | 86.6 EB05 60.3 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious n=22 · ♀ 0% (drug 37%) | not reported in cached trials |
| Bone metabolism disorder | 13 | 97.4 55.9–169.8ROR 97.5 · χ² 1,096 / p 1e-240 | 82.3 EB05 51.2 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
Trial evidence (ClinicalTrials.gov)
✓ Trial adverse-event data found on ClinicalTrials.gov
Largest completed trials with posted results that list Abacavir as a study intervention. The right-hand column of the signal table shows whether each FAERS term was also recorded in these trials, with a real denominator (0 of 40 signal terms matched).
- NCT00118898 — Efavirenz or Atazanavir/Ritonavir Given With Emtricitabine/Tenofovir Disoproxil Fumarate or Abacavir/Lamivudin (N=1864, PHASE3; 140 AE terms posted; arms: EFV, FTC/TDF, and Placebo ABC/3TC; EFV, Placebo FTC/TDF, and ABC/3TC; RTV-boosted ATV, FTC/TDF, and Placebo AB; RTV-boosted ATV, Placebo FTC/TDF, and AB)
Caveats: trial populations, doses and follow-up differ from the reporting population; AE terms are sponsor-coded and matched here by wording; absence from a trial list means the term was not reported above the sponsor's frequency threshold, not that it cannot occur.
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Pain | 880 | 3.1 2.9–3.3ROR 3.3 · χ² 1,285 / p 8e-282 | 3.1 EB05 2.9 · IC025 +1.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.9 | NCT00118898: 1/462 (0.2%) on Abacavir; 2/464 (0.4%) control (serious AE) |
| Pyrexia (fever) | 851 | 5.3 5.0–5.7ROR 5.8 · χ² 3,034 / p <1e-300 | 5.3 EB05 5.0 · IC025 +2.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 3.9 | NCT00118898: 1/464 (0.2%) on Abacavir; 3/461 (0.7%) control (serious AE) |
| Nausea | 656 | 1.8 1.7–1.9ROR 1.9 · χ² 242 / p 8e-55 | 1.8 EB05 1.7 · IC025 +0.7 | Labeled adverse reaction exact term | serious PRR 2.0 · ♀ 63% (drug 37%) | NCT00118898: 77/461 (16.7%) on Abacavir; 58/461 (12.6%) control |
| Rash | 595 | 3.0 2.8–3.2ROR 3.1 · χ² 793 / p 1e-174 | 3.0 EB05 2.8 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.7 · ♀ 69% (drug 37%) | NCT00118898: 1/462 (0.2%) control (serious AE) |
| Off label use (used outside approved label) | 582 | 1.5 1.3–1.6ROR 1.5 · χ² 85 / p 1e-20 | 1.5 EB05 1.4 · IC025 +0.4 | Reporting / coding artifact | serious PRR 1.6 · ♀ 88% (drug 37%) | not reported in cached trials |
| Vomiting | 578 | 2.7 2.5–2.9ROR 2.8 · χ² 616 / p 3e-136 | 2.7 EB05 2.5 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.3 · ♀ 64% (drug 37%) | NCT00118898: 1/462 (0.2%) on Abacavir; 1/464 (0.2%) control (serious AE) |
| Exposure during pregnancy | 565 | 19.8 18.3–21.5ROR 21.0 · χ² 10,029 / p <1e-300 | 19.7 EB05 18.3 · IC025 +4.1 3/3 methods agree | Reporting / coding artifact | serious PRR 17.4 · ♀ 100% (drug 37%) · 92% clinician | not reported in cached trials |
| Hepatic enzyme increased | 562 | 18.0 16.6–19.6ROR 19.1 · χ² 8,986 / p <1e-300 | 17.9 EB05 16.7 · IC025 +4.0 3/3 methods agree | Labeled (related wording) related wording | serious PRR 15.9 · ♀ 93% (drug 37%) | not reported in cached trials |
| Hypertension (high blood pressure) | 554 | 5.7 5.2–6.1ROR 6.0 · χ² 2,142 / p <1e-300 | 5.6 EB05 5.2 · IC025 +2.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.3 · ♀ 74% (drug 37%) | NCT00118898: 27/461 (5.9%) on Abacavir; 29/461 (6.3%) control |
| Fatigue (tiredness) | 545 | 1.5 1.4–1.6ROR 1.6 · χ² 100 / p 8e-24 | 1.5 EB05 1.4 · IC025 +0.5 | Labeled adverse reaction exact term | serious PRR 1.7 | NCT00118898: 49/461 (10.6%) on Abacavir; 41/461 (8.9%) control |
| Headache | 542 | 1.9 1.7–2.0ROR 1.9 · χ² 227 / p 1e-51 | 1.9 EB05 1.7 · IC025 +0.8 | Labeled adverse reaction exact term | serious PRR 2.3 · ♀ 74% (drug 37%) | NCT00118898: 1/464 (0.2%) control (serious AE) |
| Hypersensitivity (allergic reaction) | 518 | 6.1 5.6–6.6ROR 6.4 · χ² 2,199 / p <1e-300 | 6.0 EB05 5.6 · IC025 +2.4 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 6.6 · ♀ 83% (drug 37%) | NCT00118898: 5/461 (1.1%) on Abacavir; 1/461 (0.2%) control (serious AE) |
| Treatment failure | 496 | 13.2 12.1–14.3ROR 13.8 · χ² 5,547 / p <1e-300 | 13.1 EB05 12.1 · IC025 +3.5 3/3 methods agree | Reporting / coding artifact | serious PRR 15.4 · ♀ 83% (drug 37%) · 94% clinician | not reported in cached trials |
| Virologic failure | 490 | 216.4 197.6–236.9ROR 227.9 · χ² 95,214 / p <1e-300 | 195.1 EB05 181.0 · IC025 +7.2 3/3 methods agree | Not in label — unassessed | serious n=489 · 98% clinician | not reported in cached trials |
| Drug interaction | 488 | 6.7 6.1–7.3ROR 7.0 · χ² 2,360 / p <1e-300 | 6.6 EB05 6.1 · IC025 +2.6 3/3 methods agree | Reporting / coding artifact | serious PRR 4.5 · 91% clinician | not reported in cached trials |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Progressive external ophthalmoplegia — n=94, PRR 5,735.5
- Total lung capacity increased — n=99, PRR 1,236.4
- Genetic polymorphism — n=20, PRR 1,154.4
- Astrocytoma malignant — n=20, PRR 569.5
- Csf hiv escape syndrome — n=24, PRR 449.6
- Mitochondrial toxicity — n=138, PRR 437.3
- Hiv viraemia — n=28, PRR 335.9
- Lipodystrophy acquired — n=286, PRR 335.6
- Temperature regulation disorder — n=246, PRR 274.9
- Viral mutation identified — n=358, PRR 231.3
✓ A hand-written Bradford Hill causality assessment exists for this drug: Abacavir ↔ Hypersensitivity reaction.
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Abacavir?
In FDA FAERS, the most frequently co-reported reaction terms for Abacavir are pain, pyrexia, nausea, rash, vomiting, hepatic enzyme increased. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Abacavir have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: HYPERSENSITIVITY REACTIONS WARNING: HYPERSENSITIVITY REACTIONS See full prescribing information for complete boxed warning. Serious and sometimes fatal hypersensitivity reactions have occurred with abacavir sulfate. ( 5.1 ) Hypersensitivity to abacavir is a multi-organ clinical syndrome.
Do FAERS signals prove that Abacavir causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 0d791375-e311-41f9-87b8-940657e6318c, effective 20201224; matched on
openfda.generic_name.exact:"ABACAVIR") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 1,044 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath - ClinicalTrials.gov API v2 (query
ABACAVIR, results-bearing studies sorted by enrollment)
Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.